Incubation Temperature (incubation + temperature)

Distribution by Scientific Domains
Distribution within Life Sciences

Selected Abstracts


The effect of incubation temperature and homogenization on the rheological nature of yogurt curd during gelation was investigated in this study. Our results indicated that the optimum incubation temperature for acid development was 45C. The minimum viscosity was observed at 40C while the maximum viscosity was at 48C. Our results also indicated that incubation temperature affected yogurt viscosity during the gelation process while homogenization had no significant effect. Increasing the incubation temperature decreased the flow behavior index and increased the consistency coefficient; homogenization increased the flow behavior index and decreased the consistency coefficient as described by a power law model. [source]


The effects of heat treatment and incubation temperature on the rheological and microstructural properties of yogurt were studied. A central composite experimental design and response surface methodology were used for data analysis. The rheological properties were determined by dynamic low amplitude oscillation and the amount of spontaneous whey separation was quantified by the volumetric flask test. Confocal scanning laser microscopy was used to examine the gel structure. The storage moduli of yogurts increased with an increase in heating temperature and a decrease in incubation temperature. The maximum loss tangent value during gelation, permeability, and amount of spontaneous whey separation of yogurts increased with a decrease in heating temperature and with an increase in incubation temperature. These parameters indicated an increased possibility for rearrangements, which was confirmed by presence of large pores in the gel network. Second order polynomial models successfully predicted the effects of heating temperature and incubation temperature on the rheological properties, permeability, and whey separation of yogurts. Whey separation was negatively correlated with storage modulus (r= -0.66), and was positively correlated with the maximum loss tangent (r= 0.63) and permeability (r= 0.78). This study demonstrates that weak yogurt gels, which have high loss tangent values, favor rearrangements in the network and the resulting network has larger pores (high permeability) and exhibits greater whey separation. [source]

The effect of sugar concentration and temperature on growth and volatile phenol production by Dekkera bruxellensis in wine

Andr Barata
Abstract The wine spoilage yeast Dekkera bruxellensis was evaluated for the production of 4-ethylphenol under low concentrations (0.02,20 g L,1) of glucose and fructose in synthetic media. Measurable amounts of 4-ethylphenol were produced over 0.2 g L,1 of each sugar. The yeast growth rate and amount of biomass formed increased from 0.2 to 20 g L,1 of glucose or fructose, being accompanied by increasing production of 4-ethylphenol. In red wines, the production of 4-ethylphenol was only observed in the presence of growing populations of indigenous or inoculated strains of D. bruxellensis. The production rate of 4-ethylphenol varied between 22 and 93 ,g day,1 either with inoculated strains or wild populations in bottled wines. The production rate of 4-ethylphenol as a function of the increase in the number of cells varied from 349 to 1882 ,g L,1 per one log CFU mL,1. The effect of temperature on cellular viability and 4-ethylphenol production was tested in red wines with indigenous or inoculated strains of D. bruxellensis. Incubation temperatures of 15, 20 and 25 C allowed cellular growth and volatile phenol production. Increasing incubation temperatures to 36 C induced full viability loss of 10 strains of D. bruxellensis within <12 h. [source]

Body size, locomotor speed and antipredator behaviour in a tropical snake (Tropidonophis mairii, Colubridae): the influence of incubation environments and genetic factors

J. K. Webb
Summary 1,The physical conditions experienced by reptile embryos inside natural nests can influence the size, shape and behaviour of the resultant hatchlings. Although most reptiles are tropical, the effects of incubation temperatures on offspring phenotypes have received little attention in tropical species. 2,The consequences of differences in thermal variance during incubation on offspring were studied in a tropical natricine snake (the Keelback Tropidonophismairii), which lays eggs in soil cracks of varying depths. Some 253 eggs from 19 clutches were incubated under two thermal regimes with identical mean temperatures (256 C), but temperatures in the ,variable' treatment fluctuated more (218,296 C) than those in the ,constant' temperature treatment (252,265 C). These thermal regimes were similar to those of shallow (20 cm deep) and deep (40 cm deep) soil cracks, respectively, and represent thermal conditions inside natural nests and potential nest sites. 3,Incubation temperatures affected body size, shape and antipredator behaviour of hatchling snakes. Snakes from constant temperature incubation were longer and thinner than snakes from high variance incubation. Clutch effects influenced all offspring traits, with significant interactions between clutch of origin and incubation treatment for body size, but not swimming speed or behaviour. 4,There was a significant interaction between incubation treatment and offspring sex on neonate swimming speed. Incubation under cycling thermal regimes significantly increased swimming speeds of females, but had little effect on males. Such sex differences in phenotypic responses of hatchling snakes support a major assumption of the Charnov,Bull hypothesis for the evolution of temperature-dependent sex determination. [source]

Incubation temperatures and sex ratios in Australian brush-turkey (Alectura lathami) mounds

Abstract Megapodes are exceptional among birds because they use external heat sources for incubating their eggs. In Australian brush-turkeys (Alectura lathami), this source is the heat produced by microbial decomposition in mounds of leaf litter. A recent laboratory study showed that artificial incubation of eggs at different temperatures affects the sex ratio of brush-turkey hatchlings. Here, this phenomenon is confirmed for eggs incubated in natural incubation mounds. Eggs from which females hatched were found at significantly higher incubation temperatures in the mounds (mean 33.7C) than those from which males hatched (mean 32.9C). Also, sex ratios of chicks from individual mounds were significantly correlated with mean incubation temperatures in those mounds. Furthermore, incubation temperatures differed significantly between incubation mounds during the same month of the year. Within some mounds, incubation temperatures differed up to 9C between eggs, in others this difference was only up to 1C. These latter results show that males differ in their ability to maintain stable incubation temperatures. While the effect of incubation temperatures on sex ratio is a novel discovery for any bird, it was previously suggested that incubation temperatures in megapodes also affect embryo mortality and chick survival. These combined effects of incubation temperature, and the limited ability of males to provide optimal temperatures, seem to provide answers to the question why so few birds have adopted this unusual mode of reproduction , a question asked by many behavioural ecologists and evolutionary biologists. [source]

Effect of temperature and storage media on human periodontal ligament fibroblast viability

Beatriz Dulcineia Mendes Souza
The purpose of this study was to compare the effectiveness of several storage media to preserve cultured periodontal ligament fibroblasts (PDLF) under different temperatures. The media tested were: sterile Hank's balanced salt solution (sHBSS), non-sterile HBSS (nHBSS), skimmed milk, Save-A-Tooth, Minimum Essential Medium (MEM) and water (negative control). MEM at 37C was used as positive control. PDLF were obtained from explants of extracted healthy human teeth. Plates containing confluent PDLF were soaked in the various media for 3, 6, 24, 48 and 72 h at 37C and 20C. After incubation, viability of the cells was determined using the tetrazolium salt-based colorimetric (MTT) assay and the Trypan Blue exclusion test after 6, 24, 48 and 72 h of incubation at 20C. The results were analyzed statistically using Kruskal,Wallis, Scheff and Mann,Whitney (, = 5%) tests. Results from the MTT assay at 37C and 20C showed that skimmed milk was the best storage medium for up to 24 and 48 h, respectively, followed by nHBSS and sHBSS. Results from the Trypan Blue exclusion test showed that the best storage media were milk, sHBSS and nHBSS, with no statistical differences, for any time period. The Save-A-Tooth had a detrimental effect on cells after 24 h. The influence of temperature on the effectiveness of the storage media tested showed at 20C a decreasing order of efficacy as follows: milk > sHBSS and nHBSS > MEM > Save-A-Tooth > water while at 37C it was: MEM > nHBSS > milk > sHBSS > Save-A-Tooth > water. In conclusion, incubation temperature altered the effectiveness of the storage media and skimmed milk at 20C was better than HBSS in maintaining PDLF viability. [source]

Embryonic origin of mate choice in a lizard with temperature-dependent sex determination

Oliver Putz
Abstract Individual differences in the adult sexual behavior of vertebrates are rooted in the fetal environment. In the leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), hatchling sex ratios differ between incubation temperatures, as does sexuality in same-sex animals. This variation can primarily be ascribed to the temperature having direct organizing actions on the brain. Here we demonstrate that embryonic temperature can affect adult mate choice in the leopard gecko. Given the simultaneous choice between two females from different incubation temperatures (30.0 and 34.0,C), males from one incubation temperature (30.0,C) preferred the female from 34.0,C, while males from another incubation temperature (32.5,C) preferred the female from 30.0,C. We suggest that this difference in mate choice is due to an environmental influence on brain development leading to differential perception of opposite-sex individuals. This previously unrecognized modulator of adult mate choice lends further support to the view that mate choice is best understood in the context of an individual's entire life-history. Thus, sexual selection results from a combination of the female's as well as the male's life history. Female attractiveness and male choice therefore are complementary. 2005 Wiley Periodicals, Inc. Dev Psychobiol 48: 29,38, 2006. [source]

High-sensitive determination of human ,-thrombin by its 29-mer aptamer in affinity probe capillary electrophoresis

Yilin Li
Abstract ACE technique provides an effective tool for the separation and identification of disease-related biomarkers in clinical analysis. In recent years, a couple of synthetic DNA or RNA oligonucleotides, known as aptamers, rival the specificity and affinity for targets to antibodies and are employed as one kind of powerful affinity probe in ACE. In this work, based on high affinity between antithrombin aptamer and thrombin (their dissociation constant is 0.5,nM), a carboxyfluorescein-labeled 29-nucleotide (nt) aptamer (F29-mer) was used and an aptamer-based affinity probe CE (aptamer-based APCE) method was successfully established for high-sensitive detection and quantitative analysis of thrombin. Experimental conditions including incubation temperature and time, buffer composition, and concentration of cations were investigated and optimized. Under the optimized condition, the linear range was from 0 to 400,nM and the LOD was 2,nM (74,ng/mL, S/N,=,3), i.e., 40,amol, both in running buffer and in 5% v/v human serum. This LOD is the lowest one than those achieved by the previous APCE methods but based on a 15-mer aptamer. This approach offers a promising method for the rapid, selective, and sensitive detection of thrombin in practical utility. Further binding experiments using one carboxyfluorescein-labeled aptamer and the other nonlabeled aptamer or vice versa were carried out to deduce the formation of ternary complex when these two aptamers coexisted in the free solution with thrombin. [source]

Topical dose delivery in the reptilian egg treatment model

Jennifer K. Muller
Abstract Developing assays to detect endocrine-mediated toxicity from in ovo or in utero exposure is a current challenge in regulatory toxicology. Some species of reptiles exhibiting a unique mode of sex determination, in which the incubation temperature during a critical period determines gonadal sex, have been explored as an in ovo model to screen environmental contaminants for endocrine effects. We critically review published egg-exposure studies and conclude that data regarding the pharmacokinetics of topically applied substances are insufficient to validate dose,response relationships for the effects of chemicals on in ovo endocrine function or gender determination in reptiles. The insufficiencies in these data largely result from methodological failures, including lack of measurement verification, failure to investigate and control extraneous factors affecting the measurements, and lack of independent replication of results. Considerable additional research will be necessary to alleviate these methodological inadequacies. Given the current status of the data, topical treatment of reptilian eggs cannot be considered to be a valid means of establishing causal relationships between chemical treatment and biological outcome. [source]


EVOLUTION, Issue 10 2005
Daniel A. Warner
Abstract Why is the sex of many reptiles determined by the temperatures that these animals experience during embryogenesis, rather than by their genes? The Charnov-Bull model suggests that temperature-dependent sex determination (TSD) can enhance maternal fitness relative to genotypic sex determination (GSD) if offspring traits affect fitness differently for sons versus daughters and nest temperatures either determine or predict those offspring traits. Although potential pathways for such effects have attracted much speculation, empirical tests largely have been precluded by logistical constraints (i.e., long life spans and late maturation of most TSD reptiles). We experimentally tested four differential fitness models within the Charnov-Bull framework, using a short-lived, early-maturing Australian lizard (Amphibolurus muricatus) with TSD. Eggs from wild-caught females were incubated at a range of thermal regimes, and the resultant hatchlings raised in large outdoor enclosures. We applied an aromatase inhibitor to half the eggs to override thermal effects on sex determination, thus decoupling sex and incubation temperature. Based on relationships between incubation temperatures, hatching dates, morphology, growth, and survival of hatchlings in their first season, we were able to reject three of the four differential fitness models. First, matching offspring sex to egg size was not plausible because the relationship between egg (offspring) size and fitness was similar in the two sexes. Second, sex differences in optimal incubation temperatures were not evident, because (1) although incubation temperature influenced offspring phenotypes and growth, it did so in similar ways in sons versus daughters, and (2) the relationship between phenotypic traits and fitness was similar in the two sexes, at least during preadult life. We were unable to reject a fourth model, in which TSD enhances offspring fitness by generating seasonal shifts in offspring sex ratio: that is, TSD allows overproduction of daughters (the sex likely to benefit most from early hatching) early in the nesting season. In keeping with this model, hatching early in the season massively enhanced body size at the beginning of the first winter, albeit with a significant decline in probability of survival. Thus, the timing of hatching is likely to influence reproductive success in this short-lived, early maturing species; and this effect may well differ between the sexes. [source]

Reproductive strategies of Gammarus lacustris (Crustacea: Amphipoda) along an elevation gradient

Wilhelm F. M.
Abstract 1.,The number of eggs, their size, mass and development time, and the starvation time of newly hatched young, was examined in four populations of Gammarus lacustris along an elevation gradient from prairie to alpine lakes (730 m to > 2300 m above sea level). Water temperature and ice-free season decreased with increasing altitude. 2.,Females in the alpine lake produced fewer but larger and heavier eggs than females in the prairie lake. Eggs produced by females in montane and subalpine lakes were intermediate in size, mass and number. Within populations, egg size was not related to the number of eggs or female size. 3.,The development time of eggs declined with an increase in incubation temperature. At all incubation temperatures, large eggs had a longer incubation time than small eggs. All eggs incubated at 4 C failed to produce young. Young from large eggs were larger in size than young from small eggs. 4.,The starvation time of newly hatched young increased with decreasing temperature. However, slopes of regressions relating starvation time to temperature differed among populations. At 4 C young from large eggs survived longer than young from small eggs. 5.,The high phenotypic plasticity in reproductive traits contributes to the success of G. lacustris in a wide range of aquatic habitats. It is predicted that in response to climate-induced warming, populations in currently cold montane and alpine lakes would shift their reproduction to produce more eggs of smaller size. However, the accurate prediction of the fate of populations between ecoregions will require knowledge of the extent to which these traits are under genetic control. [source]

Temperature dependence of Fe(III) and sulfate reduction rates and its effect on growth and composition of bacterial enrichments from an acidic pit lake neutralization experiment

GEOBIOLOGY, Issue 4 2005
ABSTRACT Microbial Fe(III) and sulfate reduction are important electron transport processes in acidic pit lakes and stimulation by the addition of organic substrates is a strategy to remove acidity, iron and sulfate. This principle was applied in a pilot-scale enclosure in pit lake 111 (Brandenburg, Germany). Because seasonal and spatial variation of temperature may affect the performance of in situ experiments considerably, the influence of temperature on Fe(III) and sulfate reduction was investigated in surface sediments from the enclosure in the range of 4,28 C. Potential Fe(III) reduction and sulfate reduction rates increased exponentially with temperature, and the effect was quantified in terms of the apparent activation energy Ea measuring 42,46 kJ mol,1 and 52 kJ mol,1, respectively. Relatively high respiration rates at 4 C and relatively low Q10 values (,2) indicated that microbial communities were well adapted to low temperatures. In order to evaluate the effect of temperature on growth and enrichment of iron and sulfate-reducing bacterial populations, MPN (Most Probable Number) dilution series were performed in media selecting for the different bacterial groups. While the temperature response of specific growth rates of acidophilic iron reducers showed mesophilic characteristics, the relatively high specific growth rates of sulfate reducers at the lowest incubation temperature indicated the presence of moderate psychrophilic bacteria. In contrast, the low cell numbers and low specific growth rates of neutrophilic iron reducers obtained in dilution cultures suggest that these populations play a less significant role in Fe and S cycling in these sediments. SSCP (Single-Strand Conformation Polymorphism) or DGGE (Denaturing Gradient Gel Electrophoresis) fingerprinting based on 16S rRNA genes of Bacteria indicated different bacterial populations in the MPN dilution series exhibiting different temperature ranges for growth. [source]

Ecometrics: The traits that bind the past and present together

Abstract We outline here an approach for understanding the biology of climate change, one that integrates data at multiple spatial and temporal scales. Taxon-free trait analysis, or "ecometrics," is based on the idea that the distribution in a community of ecomorphological traits such as tooth structure, limb proportions, body mass, leaf shape, incubation temperature, claw shape, any aspect of anatomy or physiology can be measured across some subset of the organisms in a community. Regardless of temporal or spatial scale, traits are the means by which organisms interact with their environment, biotic and abiotic. Ecometrics measures these interactions by focusing on traits which are easily measurable, whose structure is closely related to their function, and whose function interacts directly with local environment. Ecometric trait distributions are thus a comparatively universal metric for exploring systems dynamics at all scales. The main challenge now is to move beyond investigating how future climate change will affect the distribution of organisms and how it will impact ecosystem services and to shift the perspective to ask how biotic systems interact with changing climate in general, and how climate change affects the interactions within and between the components of the whole biotic-physical system. We believe that it is possible to provide believable, quantitative answers to these questions. Because of this we have initiated an IUBS program iCCB (integrative Climate Change Biology). [source]

Aligned Nanocables: Controlled Sheathing of CuO Nanowires by a Self-Assembled Tubular Glycolipid,

Y. Zhou
Aligned nanocables, consisting of CuO nanowire cores and lipid nanotube shells, are prepared by sheathing an aligned array of CuO nanowires with a self-assembled tubular glycolipid (see figure). The sheath thickness of the nanocable is tunable by changing the incubation temperature of the lipid on the CuO nanowire. [source]

Influence of starter culture type and incubation temperatures on rheology and microstructure of low fat set yoghurt

The effects of different cultures and incubation temperatures on the physical properties of low fat yoghurts were investigated. The samples were incubated with exopolysaccharide (EPS)-producing and non-EPS-producing cultures at 37, 42 and 45C. All measured parameters except firmness were influenced by culture type and incubation temperature. Firmness, G, and G, were maximised at 42C for both cultures. Increased incubation temperature and EPS culture led to a higher water-holding capacity but lower syneresis, G, and G,. The EPS treatment incubated at 37C showed even lower syneresis than non-EPS treatments incubated at higher temperatures. [source]

Preliminary investigation of the combined effect of heat treatment and incubation temperature on the viability of the probiotic micro-organisms in freshly made yogurt

The combined effects of heat treatment and incubation temperature were studied on the viability and fermentation time of probiotics in ABY 1 probiotic yogurt (Lactobacillus acidophilus, Bifidobacterium spp. and yogurt bacteria). Three levels of heat treatment (85C for 30 min, 95C for 5 min and 95C for 15 min) and three levels of incubation temperature (37, 40 and 44C) were selected. At the end of fermentation, the maximum viability of probiotics (for both L. acidophilus and Bifidobacterium spp.) was observed when the milk was heated at 95C for 15 min and incubated at 37C. Incubation time was only affected by the incubation temperature and, at 37C, the longest incubation time of about 6 h was needed to achieve the highest viable counts of L. acidophilus and Bifidobacterium spp. [source]

Key Issues Concerning Biolog Use for Aerobic and Anaerobic Freshwater Bacterial Community-Level Physiological Profiling

Bradley W. Christian
Abstract Bacterial heterotrophy in aquatic ecosystems is important in the overall carbon cycle. Biolog MicroPlates provide information into the metabolic potential of bacteria involved in carbon cycling. Specifically, Biolog EcoPlates were developed with ecologically relevant carbon substrates to allow investigators to measure carbon substrate utilization patterns and develop community-level physiological profiles from natural bacterial assemblages. However, understanding of the functionality of these plates in freshwater research is limited. We explored several issues of EcoPlate use for freshwater bacterial assemblages including inoculum density, incubation temperature, non-bacterial color development, and substrate selectivity. Each of these has various effects on plate interpretation. We offer suggestions and techniques to resolve these interpretation issues. Lastly we propose a technique to allow EcoPlate use in anaerobic freshwater bacterial studies. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Chromium nanoparticle exhibits higher absorption efficiency than chromium picolinate and chromium chloride in Caco-2 cell monolayers

L.-Y. Zha
Summary This study was conducted to determine whether chromium nanoparticle (CrNano) exhibited higher absorption efficiency and possessed unique absorption mechanism in comparison to chromium picolinate (CrPic) and chromium chloride (CrCl3), as was postulated by previous reports. Twenty-one-day-old Caco-2 cell monolayers grown on semipermeable membranes in Snapwell tissue culture bichambers were incubated with CrNano, CrPic or CrCl3 to examine their transport and uptake respectively. In the concentration range of 0.2,20 ,mol/l, transport of CrNano, CrPic and CrCl3 across Caco-2 monolayers both in apical-to-basolateral and basolateral-to-apical direction was concentration-, and time-dependent, and temperature independent. The apparent permeability coefficient (Papp) of CrNano was between 5.89 and 7.92 10,6 cm/s and that of CrPic and CrCl3 was between 3.52 and 5.31 10,6 cm/s and between 0.97 and 1.37 10,6 cm/s respectively. Uptake of CrNano, CrPic and CrCl3 by both apical and basolateral membranes was concentration- and time-dependent. Uptake of CrNano by apical membrane was significantly (p < 0.05) decreased when the incubation temperature was reduced from 37 C to 4 C. The transport efficiency of CrNano, CrPic and CrCl3 after incubation for 120 min at 37 C was 15.83% 0.76%, 9.08% 0.25% and 2.11% 0.53% respectively. The uptake efficiency of CrNano, CrPic and CrCl3 was 10.08% 0.76%, 4.73% 0.60% and 0.88% 0.08% respectively. It was concluded that the epithelial transport of CrNano, CrPic and CrCl3 across the Caco-2 cell monolayers was mainly via passive transport pathways. In addition, CrNano exhibited considerably higher absorption efficiency than both CrPic and CrCl3 in Caco-2 cell monolayers. [source]

Isolation of entomopathogenic fungi from the soil and their pathogenicity to two fruit fly species (Diptera: Tephritidae)

P. Sookar
Abstract The occurrence of deuteromycetous entomopathogenic fungi was determined by examining 224 soil samples from 19 locations in three climatic zones of Mauritius. Three sites were sampled per location: one site under vegetables cultivation, one site under sugar cane plantation and one natural site each within 1 km of each other. Soil samples were baited with the waxmoth larvae Galleria mellonella L. and incubated in the dark at 15, 20, 25 or 30C for 7, 14 and 21 days. Entomopathogenic fungi were isolated from 77 out of 224 (38.6%) soil samples. Metarhizium anisopliae was isolated from 42 (18.8%) samples, Beauveria bassiana from 24 (10.7%), Metarhizium spp. and Paecilomyces fumosoroseus from 5 (2.2%) each and Beauveria spp. from 1 (0.4%). It was observed that M. anisopliae was isolated more frequently from soils under vegetables as compared to soils under sugarcane or habitat with natural vegetation. Beauveria bassiana was isolated more frequently at the lowest incubation temperature (15C) while M. anisopliae isolates were recovered more frequently at higher temperatures (25 and 30C). The pathogenicity of seven isolates of M. anisopliae, five isolates of B. bassiana and two isolates of P. fumosoroseus towards the adults of Bactrocera zonata and Bactrocera cucurbitae was tested by topical application of conidial suspension of 1 106 conidia/ml. All the isolates tested were pathogenic to the two fruit fly species. Mortality of B. zonata varied between 12.0 and 98.0% and between 2.0 and 94.0% in B. cucurbitae at 5 days post-treatment. Our results suggest that entomopathogenic fungi present locally, could be integrated for the control of B. zonata and B. cucurbitae. [source]

Growth of pure cultures of Verocytotoxin-producing Escherichia coli in a range of enrichment media

C.L. Baylis
Abstract Aims:, This study compared the growth of different strains of Verocytotoxin-producing Escherichia coli (VTEC) in a range of selective enrichment media. Methods and Results:, Turbidometric and impedance methods were used to determine the growth of VTEC in pure culture in different enrichment media. Ten strains failed to grow in buffered peptone water + vancomycin, cefsulodin, cefixime at 42C and some failed to grow, or grew poorly in E. coli (EC) medium supplemented with 20 mg l,1 novobiocin and modified EC supplemented with 20 mg l,1 novobiocin at 37C and 42C. Individual VTEC strains were sensitive to the selective agents in some media. Statistical analysis of the conductance detection times of 10 strains showed no overall effect of temperature alone (P = 066) but there were significant (P < 0001) effects as a result of the combination of medium and temperature and these two factors were influenced by strain. Conclusions:, Growth of VTEC during enrichment is dependent on different factors alone or in combination. These include medium type, presence of certain selective agents or antibiotics, incubation temperature and the initial population of VTEC. Sensitivity to these conditions can be strain related. Significance and Impact of the Study:, This study highlighted differences in the ability of some enrichment media to support the growth of VTEC, making them unsuitable for the isolation of VTEC, especially low numbers of non-O157 strains. [source]

Effect of culture conditions on lactic acid production of Tetragenococcus species

T. Kobayashi
Abstract Aims:, To investigate the effects of the salt concentration, incubation temperature and initial pH of the medium on the fermentative ability of the halophilic lactic acid bacteria, Tetragenococcus muriaticus and T. halophilus. Method and Results:, The growth, lactic acid production and pH reduction ability of five strains of T. muriaticus and T. halophilus in MRS broth medium under various culture conditions such as salt concentration (3, 7, 15 and 23% NaCl), temperature (20, 30 and 40C), and initial medium pH (58, 65 and 75) were investigated. Those of T. halophilus were seriously affected by a high salinity (23% NaCl); in contrast, those of T. muriaticus were affected by a low initial pH (58). Conclusions:, The results indicate that high saline concentrations and low pH values have significant impact on the growth, lactic acid production and pH reduction ability of T. halophilus and T. muriaticus, respectively. Significance and Impact of the Study:, This study appears to be important in biopreservation during the manufacture of fermented food products. Both T. muriaticus and T. halophilus may support each other in reducing pH in hypersaline or low pH environment. To our knowledge, this is the first report on the fermentation ability of T. muriaticus. [source]

The effects of temperature, water activity and pH on the growth of Aeromonas hydrophila and on its subsequent survival in microcosm water

M. Sautour
Abstract Aims: The influence of temperature, water activity and pH on the growth of Aeromonas hydrophila, and on its survival after transfer in nutrient-poor water were assessed. Methods and Results: Experiments were carried out according to a Box,Behnken matrix at 10,30C, 095,099 water activity (aw) and pH 5,9. The effect of each factor on the kinetic parameters of growth (i.e. the maximal specific growth rate, ,max, and the lag time, ,) and on the decline of the bacteria in microcosm water (time to obtain a reduction of 5 log, T5 log) were studied by applying central composite design. Conclusions: The major effect of temperature and water activity on the growth of A. hydrophila was highlighted, whereas the effect of pH in these experimental conditions was not significant. Models describing the effect of environmental parameters on the growth of A. hydrophila were proposed. The effect of the growth environment, and particularly the incubation temperature, have an influence on the survival ability of the bacteria in nutrient-poor water. Significance and Impact of the Study: The Box,Behnken design was well suited to determine the influence of environmental factors on the growth of A. hydrophila and to investigate the effect of previous growth conditions on its survival in microcosm water. [source]

Relevance of incubation temperature for Vibrio salmonicida vaccine production

D.J. Colquhoun
Aims:,To investigate the relationships between water temperature, bacterial growth, virulence and antigen expression in Vibrio salmonicida, the causal agent of cold water vibriosis in Atlantic salmon (Salmo salar L.). Methods and Results:,The significance of sea temperature was investigated using historical clinical and oceanographic data. An upper threshold for disease of approx. 10C was established. The effects of culture temperature and media type on bacterial growth were studied on solid and in liquid media. The highest rates of cell division were identified at 15C on solid media and 10C in liquid media. Outer membrane protein (OMP) expression and serological response in Atlantic salmon were studied using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, Western blotting and enzyme-linked immunosorbent assay. A novel 76-kDa OMP produced in unshaken cultures at 10C was not found to stimulate a specific humoral response. Conclusions:,Diagnostic agar plate-based incubation of suspected V. salmonicida should be carried out at 15C. High yield broth cultures for vaccine production should be incubated at 10C or lower. Significance and Impact of the Study:,This study is, to the best of our knowledge, the first to identify different optimal temperatures in a bacterial species cultured on physically different types of media. The evidence presented suggests that V. salmonicida and possibly other bacteria destined for vaccine use in poikilothermic organisms should be cultured at temperatures consistent with that at which disease occurs. [source]

Experimental reduction of incubation temperature affects both nestling and adult blue tits Cyanistes caeruleus

Johan F. Nilsson
Incubation was for a long time considered to be a period of decreased activity and low cost for parents. It was therefore ignored as a potential factor affecting life-history trade-offs in birds. Lately this view has started to change, and studies now show that there might be considerable costs connected to incubation. We experimentally reduced the nest temperature during incubation in blue tits Cyanistes caeruleus, thus increasing the energetic cost of incubation, to test the importance of incubation as a component of reproductive costs and for nestling quality. While most other studies use brood size manipulation to manipulate reproductive costs, we were able to separate treatment effects acting during the incubation period from those acting on later reproductive performance by applying a cross-foster design. We were also able to isolate the effects of decreased incubation temperature on the nestlings from treatment effects acting on incubating females. We found no experimental effect on the length of the incubation period or on hatching success. The lower temperature during incubation, however, caused lower growth rates in nestlings and reduced chick rearing capacity in adults. We conclude that incubation is a costly period, with the potential to affect both the trade-off between current and future reproduction and the one between parental effort and offspring quality within the current breeding attempt. [source]

Optimization of trehalose production by a novel strain Brevibacterium sp.

Abstract Trehalose production by a novel strain of Brevibacterium sp. SY361 was optimized in submerged fermentation. Different chemical and physical parameters such as carbon and nitrogen sources, inoculum level, initial pH, incubation temperature, aeration and time-course of fermentation, were studied in order to increase trehalose productivity. An optimal production medium containing 3% (w/v) glucose, 0.9% (v/v) corn steep liquor, 0.5% (w/v) KH2PO4 and 0.4% (w/v) MgSO47 H2O was found suitable for trehalose production. An optimal volume of medium in a 500 ml flask was 80 ml. The optimal levels of other parameters were 4.0% (v/v) of inoculum, initial pH of 6.0, incubation temperature of 28,32 C and time-course of 60 h. Optimized parameters gave a maximum trehalose of 12.2 mg/ml with a conversion rate of 58.4%. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Sequential parametric optimization of lipase production by a mutant strain Rhizopus sp.

Lipase production by the mutant strain Rhizopus sp. BTNT-2 was optimized in submerged fermentation. Different chemical and physical parameters such as carbon sources, nitrogen sources, oils, inoculum level, pH, incubation time, incubation temperature and aeration have been extensively studied to increase lipase productivity. Potato starch (1.25% w/v) as a carbon source, corn steep liquor (1.5% w/v) as a nitrogen source and olive oil (0.5% v/v) as lipid source were found to be optimal for lipase production. The optimal levels of other parameters are 4 ml of inoculum (2.6 108 spores/ml), initial pH of 5.5, incubation time of 48 hours, incubation temperature of 28 C and aeration rate of 120 rpm. With the optimized parameters, the highest production of lipase was 59.2 U/ml while an yield of only 28.7 U/ml was obtained before optimization resulting in 206% increase in the productivity. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The relationship of oocyte diameter and incubation temperature to incubation time in temperate freshwater fish species

F. Teletchea
Based on the analysis of six egg variables and incubation temperature of 65 temperate freshwater fish species, the possible relationships between oocyte diameter, incubation time and incubation temperature were reassessed and compared to the results obtained from marine fishes. Most freshwater species have eggs (mean s.d. 219 152 mm) larger than marine species, that are chiefly demersal and develop stuck to various substrata, such as plants or rocks. A strong negative relationship was found between incubation time (t, days) and incubation temperature (T, C): t = 18623e,0197T (r2= 087). A strong dependence of incubation time on oocyte diameter (, mm) and incubation temperature was also found and was defined as: log10t= 3002 + 0599 log10, 191 log10 (T + 2), which explained 92% of the variance of the data set. Five major groups of species were defined based on the principal component analysis (PCA) of four quantitative variables. There were two distinct groups of salmonids, displaying demersal and non-adhesive eggs with a long incubation time at low temperature, the eggs of which required a high number of degree-days. There was a large group of species possessing small, mostly demersal and adhesive eggs developing at high temperature during a short period of time, and requiring a low number of degree-days. Between these two extremes, there was a fourth group displaying intermediate values and a fifth group including three species with large, adhesive and demersal eggs incubating at high temperatures during a short period of time. The burbot Lota lota displayed an unusual combination of variables compared to the remaining species in the data set. [source]

Teratogenicity of elevated egg incubation temperature and egg vitamin A status in Atlantic salmon, Salmo salar L.

R rnsrud
Abstract The present study was undertaken to investigate the possibility that high egg vitamin A (VA) status in combination with elevated egg incubation temperatures may cause deformities in Atlantic salmon, Salmo salar L. Egg batches selected for their total VA concentration were exposed to low (normal, 8 C) or elevated (14 C) egg incubation temperatures. Temperature was the main factor causing bone deformities such as warped gill opercula, fin and jaw deformities, but not for the development of spinal deformities where all groups displayed a ,baseline' occurrence of mild deformity (decreased vertebral size in the cephalic region) and no systematic variation in the occurrence of serious spinal deformities (fused vertebrae). A possible effect of egg incubation temperature fluctuation was found for the groups reared at low temperatures. An indication of a negative effect of elevated egg VA status for the development of organ deformities such as missing septum transversum and situs inversus was found in addition to temperature effects, however, no firm conclusions could be drawn from the present data. The phenotypes for temperature-induced deformities resembled the phenotype of VA-induced deformities, but no clear conclusions on the causality of the deformities found in the present study could be drawn. Egg incubation temperatures, both absolute temperature and temperature variations, should therefore be strictly controlled. [source]


ABSTRACT Response surface methodology was used to optimize the processing conditions in the preparation of cowpea tempeh. The independent factors studied were boiling time (varying from 5 to 30 min), incubation time (varying from 12 to 48 h) and incubation temperatures (varying from 25 to 50C), whereas the dependent factors were protein content, protein solubility, pH, titratable acidity and total color difference (using L, a* and b*). Regression models were generated and adequacy was tested with regression coefficients (R2) and the lack-of-fit tests. Optimum processing conditions were determined by method of superimposition. There was a strong and significant influence (P < 0.01) of the quadratic effect of the incubation time on the protein content of the cowpea tempeh, with similar significance (P < 0.01) noted in protein solubility with increasing boiling time. The optimum processing conditions observed for the preparation of cowpea tempeh were boiling time of about 20 min, incubation time of about 28 h and incubation temperature of about 37C. PRACTICAL APPLICATIONS Response surface methodology (RSM), as a statistical tool, has been effectively used in food process applications. This study embraced the use of RSM in the optimization of the processing conditions involved in the preparation of cowpea tempeh. Superimposition of the contour plots developed from the regression models indicated that cowpea with optimum quality characteristics should be processed at a boiling time of 20 min, incubation time of 28 h and incubation temperature of 37C. These conditions could be adopted for the industrial production of cowpea tempeh. [source]


The effect of incubation temperature and homogenization on the rheological nature of yogurt curd during gelation was investigated in this study. Our results indicated that the optimum incubation temperature for acid development was 45C. The minimum viscosity was observed at 40C while the maximum viscosity was at 48C. Our results also indicated that incubation temperature affected yogurt viscosity during the gelation process while homogenization had no significant effect. Increasing the incubation temperature decreased the flow behavior index and increased the consistency coefficient; homogenization increased the flow behavior index and decreased the consistency coefficient as described by a power law model. [source]