Isolation of sulfate-reducing bacteria from the terrestrial deep subsurface and description of Desulfovibrio cavernae sp. nov

Deep subsurface sandstones in the area of Berlin (Germany) located 600 to 1060 m below the surface were examined for the presence of viable microorganisms. The in situ temperatures at the sampling sites ranged from 37 to 45 degrees C. Investigations focussed on sulfate-reducing bacteria able to grow on methanol and triethylene glycol, which are added as chemicals to facilitate the long-term underground storage of natural gas. Seven strains were isolated from porewater brines in the porous sandstone. Three of them were obtained with methanol (strains H1M, H3M, and B1M), three strains with triethylene glycol (strains H1T, B1T, and B2T) and one strain with a mixture of lactate, acetate and butyrate (strain H1-13). Due to phenotypic properties six isolates could be identified as members of the genus Desulfovibrio, and strain B2T as a Desulfotomaculum. The salt tolerance and temperature range for growth indicated that the isolates originated from the indigenous deep subsurface sandstones. They grew in mineral media reflecting the in situ ionic composition of the different brines, which contained 1.5 to 190 g NaCl x l(-1) and high calcium and magnesium concentrations. The Desulfovibrio strains grew at temperatures between 20 and 50 degrees C, while the Desulfotomaculum strain was thermophilic and grew between 30 and 65 degrees C. The strains utilized a broad spectrum of electron donors and acceptors. They grew with carbon compounds like lactate, pyruvate, formate, n-alcohols (C1-C5), glycerol, ethylene glycol, malate, succinate, and fumarate. Some strains even utilized glucose as electron donor and carbon source. All strains were able to use sulfate, sulfite and nitrate as electron acceptors. Additionally, three Desulfovibrio strains reduced manganese oxide, the Desulfotomaculum strain reduced manganese oxide, iron oxide, and elemental sulfur. The 16S rRNA analysis revealed that the isolates belong to three different species. The strains H1T, H3M and B1M could be identified as Desulfovibrio indonesiensis, and strain B2T as Desulfotomaculum geothermicum. The other Desulfovibrio strains (H1M, H1-13, and B1T) showed identical 16S rDNA sequences and similarities as low as 93% to their closest relative, Desulfovibrio aminophilusT. Therefore, these isolates were assigned to a new species, Desulfovibrio cavernae sp. nov., with strain H1M as the type strain.     

Isolation and characterization of psychotrophic bacteria from oil-reservoir water and oil sands

Four psychrotrophic strains, which grew at 4 degrees C but not at 37 degrees C, were isolated from Japanese oil-reservoir water (strains SIB1, SIC1, SIS1) and Canadian oil sands (strain CAB1). Strains SIB1, SIS1, and CAB1 had a maximum growth rate at 20 degrees C and grew to the highest cell densities at the cultivation temperature of 0-4 degrees C. Strain SIS1 was capable of growing even at -5 degrees C. The growth profile of strain SIC1 was rather similar to that of a mesophilic bacterium. Strains SIB1, SIC1, and SIS1 were identified as members of the genus Shewanella, and strain CAB1 was a member of the genus Arthrobacter. All these strains exhibited weak degradation ability against catechol, a hydroxylated aromatic hydrocarbon, and tributyrin. These strains are expected to be of potential use in the in situ bioremediation technology of hazardous hydrocarbons and esters under low-temperature conditions.     

Binding kinetics of ecotropic (Moloney) murine leukemia retrovirus with NIH 3T3 cells.

A quantitative analysis of the binding kinetics of intact Moloney murine leukemia retrovirus (MoMuLV) particles with NIH 3T3 cells was performed with an immunofluorescence flow cytometry assay. The virus-cell binding equilibrium dissociation constant (KD), expressed in terms of virus particle concentration, was measured to be 8.5 (+/- 6.4) x 10(-12) M at 4 degrees C and was three- to sixfold lower at temperatures above 15 degrees C. The KD of virus binding is about 1,000-fold lower than the KD of purified MoMuLV envelope. The association rate constant was determined to be 2.5 (+/- 0.9) x 10(9) M-1 min-1 at 4 degrees C and was 5- to 10-fold higher at temperatures above 15 degrees C. The apparent dissociation rate constant at 4 degrees C was 1.1 (+/- 0.4) x 10(-3) min-1 and was doubled for every 10 degrees C increase in temperature over the range tested (15 to 37 degrees C).     

Measurement of the affinity and phosphorylation constants governing irreversible inhibition of cholinesterases by di-isopropyl phosphorofluoridate

1. A procedure is described for determining the affinity constant K(a) and the phosphorylation constant k(p) for the inhibition by di-isopropyl phosphorofluoridate of erythrocyte acetylcholinesterase and serum cholinesterase. The procedure depends on the use of a specially designed reaction vessel with which incubation times as short as 1.2sec. could be obtained at any convenient temperature. 2. The K(a) of acetylcholinesterase decreased from 1.58 (+/-0.22)x10(-3)m at 5 degrees to 1.17 (+/-0.10)x10(-3)m at 25 degrees and the associated change in enthalpy was 2980 cal. 3. The k(p) of acetylcholinesterase increased from 11.9 (+/-0.7)min.(-1) at 5 degrees to 40.7 (+/-1.4)min.(-1) at 25 degrees , indicating an activational energy of 9600 cal. The change in entropy associated with K(a) was 23.5 cal. degree(-1) at 25 degrees . 4. At 5 degrees , the K(a) and k(p) of serum cholinesterase were 9.95 (+/-1.10)x10(-6)m and 11.2 (+/-0.63)min.(-1) respectively. 5. The 150-fold difference in the inhibitory power of di-isopropyl phosphorofluoridate for the two cholinesterases was attributed entirely to differences in affinity.     

Isolation and characterization of thermotolerant Gluconobacter strains catalyzing oxidative fermentation at higher temperatures

Thermotolerant acetic acid bacteria belonging to the genus Gluconobacter were isolated from various kinds of fruits and flowers from Thailand and Japan. The screening strategy was built up to exclude Acetobacter strains by adding gluconic acid to a culture medium in the presence of 1% D-sorbitol or 1% D-mannitol. Eight strains of thermotolerant Gluconobacter were isolated and screened for D-fructose and L-sorbose production. They grew at wide range of temperatures from 10 degrees C to 37 degrees C and had average optimum growth temperature between 30-33 degrees C. All strains were able to produce L-sorbose and D-fructose at higher temperatures such as 37 degrees C. The 16S rRNA sequences analysis showed that the isolated strains were almost identical to G. frateurii with scores of 99.36-99.79%. Among these eight strains, especially strains CHM16 and CHM54 had high oxidase activity for D-mannitol and D-sorbitol, converting it to D-fructose and L-sorbose at 37 degrees C, respectively. Sugar alcohols oxidation proceeded without a lag time, but Gluconobacter frateurii IFO 3264T was unable to do such fermentation at 37 degrees C. Fermentation efficiency and fermentation rate of the strains CHM16 and CHM54 were quite high and they rapidly oxidized D-mannitol and D-sorbitol to D-fructose and L-sorbose at almost 100% within 24 h at 30 degrees C. Even oxidative fermentation of D-fructose done at 37 degrees C, the strain CHM16 still accumulated D-fructose at 80% within 24 h. The efficiency of L-sorbose fermentation by the strain CHM54 at 37 degrees C was superior to that observed at 30 degrees C. Thus, the eight strains were finally classified as thermotolerant members of G. frateurii.     

Purification and characterization of two chymotrypsin-like proteases from the pyloric caeca of rainbow trout (Oncorhynchus mykiss).

1. Two chymotrypsins, called chymotrypsin I and II, were purified from the pyloric caeca of rainbow trout, by (NH4)2SO4 fractionation, hydrophobic interaction chromatography (phenyl-Sepharose) and ion-exchange chromatography (DEAE-Sepharose). 2. The approximate molecular weights of chymotrypsin I and II were 28,200 (+/- 1200) and 28,800 (+/- 900), respectively, as determined by SDS-PAGE and their isoelectric points were about 5. 3. The pH optima of the enzymes were centered around nine, when assayed for succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (Suc-AAPF-NA) as substrate and both enzymes were unstable at pH values below 5. 4. The amidase activity of both enzymes increased with temperature up to about 55 degrees C. Chymotrypsin I was found to be more heat stable than chymotrypsin II, an effect most likely explained by stronger calcium binding of the former. 5. The trout chymotrypsins were significantly more active than bovine alpha-chymotrypsin when assayed against Suc-AAPF-NA at 25 degrees C and casein at low temperatures (10-20 degrees C), indicating an adaptation of the activities of the trout chymotrypsins to the habitation temperatures of the fish.     

Chlorella sorokiniana UTEX 2805, a heat and intense, sunlight-tolerant microalga with potential for removing ammonium from wastewater

In the summer of 2003, a microalga strain was isolated from a massive green microalgae bloom in wastewater stabilization ponds at the treatment facility of La Paz, B.C.S., Mexico. Prevailing environmental conditions were air temperatures over 40 degrees C, water temperature of 37 degrees C, and insolation of up to 2400 micromol m2 s(-1) at midday for several hours at the water surface for four months. The microalga was identified as Chlorella sorokiniana Shih. et Krauss, based on sequencing its entire 18S rRNA gene. In a controlled photo-bioreactor, this strain can grow to high population densities in synthetic wastewater at temperatures of 40-42 degrees C and light intensity of 2500 micromol m2 s(-1) for 5h daily and efficiently remove ammonium from the wastewater under these conditions better than under normal lower temperature (28 degrees C) and lower light intensity (60 micromol m2 s(-1)). When co-immobilized with the bacterium Azospirillum brasilense that promotes growth of microalgae, the population of microalga grew faster and removed even more ammonium. Under exposure to extreme growth conditions, the quantity of four photosynthetic pigments increased in the co-immobilized cultures. This strain of microalga has potential as a wastewater treatment agent under extreme conditions of temperature and light intensity.     

Effect of temperature on life table parameters of predatory thrips Scolothrips longicornis (Thysanoptera: Thripidae) fed on twospotted spider mites (Acari: Tetranychidae)

Environmental variables such as temperature are important factors that affect the efficiency of biological control agents. This study examined the effect of temperature on the sex ratio, longevity, oviposition periods, fecundity and life table parameters of the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), at six constant temperatures: 15, 20, 26, 30, 35, and 37 degrees C. Approximately 75% of the progeny were female, except at 37 degrees C, at which temperature the proportion of males increased. Adult longevity as well as the preoviposition, oviposition, and postoviposition periods decreased significantly with temperature. Thus, adults lived for approximately 5 wk at 15 degrees C and < 1 wk at 37 degrees C with preoviposition, oviposition, and postoviposition periods ranging from 6.4 to 0.4, 24.4-3.1, and 7-0.8 d between the two temperature extremes, respectively. The maximum (56.48 eggs) and minimum (11.69 eggs) value of total fecundity was recorded at 26 and 37 degrees C, respectively. The intrinsic rate of natural increase (r(m)) of S. longicornis increased linearly with increasing temperature from 0.056 d(-1) at 15 degrees C to 0.310 d(-1) at 35 degrees C. The lower temperature threshold for the population increase of S. longicornis was estimated to be around 5 degrees C. The data suggest that the upper temperature threshold for the predatory thrips is approximately 37 degrees C. The results showed that populations of S. longicornis are able to develop at a broad range of temperatures and that this predator is well adapted to the high temperatures that occur in the Mediterranean region.     

Heat and cold shock protein synthesis in arctic and temperate strains of rhizobia.

We compared heat shock proteins (HSPs) and cold shock proteins (CSPs) produced by different species of Rhizobium having different growth temperature ranges. Several HSPs and CSPs were induced when cells of three arctic (psychrotrophic) and three temperate (mesophilic) strains of rhizobia were shifted from their optimal growth temperatures (arctic, 25 degrees C; temperate, 30 degrees C) to shock temperatures outside their growth temperature ranges. At heat shock temperatures, three major HSPs of high molecular weight (106,900, 83,100, and 59,500) were present in all strains for all shock treatments (29, 32, 36.4, 38.4, 40.7, 41.4, and 46.4 degrees C), with the exception of temperate strains exposed to 46.4 degrees C, in which no protein synthesis was detected. Cell survival of arctic and temperate strains decreased markedly with the increase of shock temperature and was only 1% at 46.4 degrees C. Under cold shock conditions, five proteins (52.0, 38.0, 23.4, 22.7, and 11.1 kDa) were always present for all treatments (-2, -5, and -10 degrees C) in arctic strains. Among temperate strains, five CSPs (56.1, 37.1, 34.4, 17.3, and 11.1 kDa) were present at temperatures down to 0 degrees C. The 34.4- and the 11.1-kDa components were present in all temperate strains at -5 degrees C and in one strain at -10 degrees C. Survival of all strains decreased with cold shock temperatures but was always higher than 50%. These results show that rhizobia can synthesize proteins at temperatures not permissive for growth. In all shock treatments, no correspondence between the number of HSPs or CSPs produced and rhizobial survival was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth of Listeria monocytogenes at refrigeration temperatures

The growth of three strains of Listeria monocytogenes at refrigeration temperatures (-0.5 to 9.3 degrees C) in chicken broth and/or UHT milk was determined using a rocking temperature gradient incubator. Minimum growth temperatures ranged from -0.1 to -0.4 degree C for the three strains. Lag times of 1-3 d and 3 to greater than 34 d were observed with incubation at 5 and 0 degrees C respectively. Corresponding generation times ranged from 13-24 h at 5 degrees C and 62-131 h at 0 degree C. The type of culture medium had an influence on both the rate and extent of growth. Incubation of cultures at 4 degrees C before inoculation caused a marked reduction in the lag time when compared with cultures which had been previously incubated at 30 degrees C.     

Heat and cold shock protein synthesis in arctic and temperate strains of rhizobia.

We compared heat shock proteins (HSPs) and cold shock proteins (CSPs) produced by different species of Rhizobium having different growth temperature ranges. Several HSPs and CSPs were induced when cells of three arctic (psychrotrophic) and three temperate (mesophilic) strains of rhizobia were shifted from their optimal growth temperatures (arctic, 25 degrees C; temperate, 30 degrees C) to shock temperatures outside their growth temperature ranges. At heat shock temperatures, three major HSPs of high molecular weight (106,900, 83,100, and 59,500) were present in all strains for all shock treatments (29, 32, 36.4, 38.4, 40.7, 41.4, and 46.4 degrees C), with the exception of temperate strains exposed to 46.4 degrees C, in which no protein synthesis was detected. Cell survival of arctic and temperate strains decreased markedly with the increase of shock temperature and was only 1% at 46.4 degrees C. Under cold shock conditions, five proteins (52.0, 38.0, 23.4, 22.7, and 11.1 kDa) were always present for all treatments (-2, -5, and -10 degrees C) in arctic strains. Among temperate strains, five CSPs (56.1, 37.1, 34.4, 17.3, and 11.1 kDa) were present at temperatures down to 0 degrees C. The 34.4- and the 11.1-kDa components were present in all temperate strains at -5 degrees C and in one strain at -10 degrees C. Survival of all strains decreased with cold shock temperatures but was always higher than 50%. These results show that rhizobia can synthesize proteins at temperatures not permissive for growth. In all shock treatments, no correspondence between the number of HSPs or CSPs produced and rhizobial survival was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and characterization of Rhodococcus sp. strains TMP2 and T12 that degrade 2,6,10,14-tetramethylpentadecane (pristane) at moderately low temperatures

Branched alkanes including 2,6,10,14-tetramethylpentadecane (pristane) are more resistant to biological degradation than straight-chain alkanes especially under low-temperature conditions, such as 10 degrees C. Two bacterial strains, TMP2 and T12, that are capable of degrading pristane at 10 degrees C were isolated and characterized. Both strains grew optimally at 30 degrees C and were identified as Rhodococcus sp. based on the 16S rRNA gene sequences. Strain T12 degraded comparable amounts of pristane in a range of temperatures from 10 to 30 degrees C and strain TMP2 degraded pristane similarly at 10 and 20 degrees C but did not degrade it at 30 degrees C. These data suggest that the strains have adapted their pristane degradation system to moderately low-temperature conditions.     

Temperature dependency of bark photosynthesis in beech (Fagus sylvatica L.) and birch (Betula pendula Roth.) trees

Temperature dependencies of stem dark respiration (R(d)) and light-driven bark photosynthesis (A(max)) of two temperate tree species (Fagus sylvatica and Betula pendula) were investigated to estimate their probable influence on stem carbon balance. Stem R(d) was found to increase exponentially with increasing temperatures, whereas A(max) levelled off or decreased at the highest temperatures chosen (35-40 degrees C). Accordingly, a linear relationship between respiratory and assimilatory metabolism was only found at moderate temperatures (10-30 degrees C) and the relationship between stem R(d) and A(max) clearly departed from linearity at chilling (5 degrees C) and at high temperatures (35-40 degrees C). As a result, the proportional internal C-refixation rate also decreased non-linearly with increasing temperature. Temperature response of photosystem II (PSII) photochemistry was also assessed. Bark photochemical yield (Delta F/F(m)') followed the same temperature pattern as bark CO(2) assimilation. Maximum quantum yield of PSII (F(v)/F(m)) decreased drastically at freezing temperatures (-5 degrees C), while from 30 to 40 degrees C only a marginal decrease in F(v)/F(m) was found. In in situ measurements during winter months, bark photosynthesis was found to be strongly reduced. Low temperature stress induced an active down-regulation of PSII efficiency as well as damage to PSII due to photoinhibition. All in all, the benefit of bark photosynthesis was negatively affected by low (<5 degrees C) as well as high temperatures (>30 degrees C). As the carbon balance of tree stems is defined by the difference between photosynthetic carbon gain and respiratory carbon loss, this might have important implications for accurate modelling of stem carbon balance.     

Response of murine bone marrow granulocyte-macrophage colony-forming units to hyperthermia in situ

A detailed understanding of how bone marrow stem cell progenitors are affected by heat is prerequisite to predicting how whole-body or regional hyperthermia protocols may affect bone marrow function. This investigation reports the reproductive integrity of murine tibial bone marrow granulocyte-macrophage colony-forming units (CFU-GM) after in situ hyperthermia. Heat was applied by water bath immersion of the leg of male BALB/c mice anesthetized with 90 mg/kg pentobarbital given subcutaneously. Tibial and rectal temperatures were monitored in representative animals by microthermocouples (tip diameter approximately 100 microns). By approximately 3 min after immersion of the limb, marrow temperature was within 0.3 degree C of water bath temperature (O'Hara et al., Int. J. Hyperthermia 5, 589-601, 1989) and was within 0.1 degree C by 5 min after immersion. The CFU-GM were cultured in "lung-conditioned" McCoy's 5A medium supplemented with 15% fetal calf serum and 0.3% Bacto agar. In situ heating of tibial marrow to exposure temperatures of 42, 42.5, 43, 44, and 45 degrees C gave D0's (+/- 95% CI) of 91 +/- 44, 44 +/- 27, 27 +/- 2.2, 16 +/- 6, and 7 +/- 4 min, respectively. Heating to 41.5 degrees C for up to 180 min did not result in cytotoxicity. Development of thermotolerance after approximately 100 min of heating was apparent by the presence of a "resistant tail" of the 42 degrees C survival curve. A plot of D0 vs water bath temperature was bimodal with an inflection point at approximately 42.5 degrees C. The inactivation enthalpy for temperatures above 42.5 degrees C was 586 kJ/mol (140 kcal/mol) and for temperatures below 42.5 degrees C was estimated to be 1205 kJ/mol (288 kcal/mol). These results show that CFU-GM can be heated predictably in situ, can be inactivated with thermal exposures as low as 42 degrees C, and are capable of developing thermotolerance. These findings underscore the necessity to understand stem cell inactivation by hyperthermia in situ prior to widespread implementation of clinical hyperthermia protocols where bone marrow may be included in the treatment field.     

Correlation of long-range membrane order with temperature-dependent growth characteristics of parent and a cold-sensitive, branched-chain-fatty-acid-deficient mutant of Listeria monocytogenes

Listeria monocytogenes is a food-borne, pathogenic, psychrotolerant bacterium that grows at refrigeration temperatures. Long-range membrane order of the parent (10403S) and of a cold-sensitive mutant ( cld-1) deficient in odd-numbered, branched-chain fatty acids was measured using the width of the central line of spectra of an electron paramagnetic resonance probe, 4,4-dimethyl-2-heptyl-2-hexyloxazolidine- N-oxyl (7N14), that locates deep in the hydrocarbon region of the membranes. The line width decreased from 0.9 to 0.5 milliTesla (mT) over the temperature range of 0-10 degrees for strain 10403S and -5 to 32 degrees C for strain cld-1 independent of protein state (heat denatured or intact). This provided new evidence for phase transitions in the membranes. When strain cld-1 was grown in medium supplemented with 2-methylbutyric acid, which restores anteiso fatty acids and the ability to grow at low temperature, the change in central line width as a function of temperature resembled that of strain 10403S. The temperatures at which the central line width became 0.8 mT corresponded to those at which growth became very slow in both strains (3-5 degrees C for 10403S, 15 degrees C for cld-1) as determined by Arrhenius plots. These data underscore the critical role of odd-numbered anteiso fatty acids in influencing the lower temperature limits of growth through their effects on long-range membrane fluidity.     

Pleiotrophic cellular deficiencies conferred by the blm5-1 mutation of Saccharomyces cerevisiae.

Mutational alteration of the BLM5 gene of the model eukaryote, Saccharomyces cerevisiae, confers extreme hypersensitivities to lethal effects of ionizing radiation, anticancer bleomycins and structurally-related phleomycins. Additional properties conferred by the blm5-1 mutation in haploid and diploid strains were investigated for the current report. Only one copy of blm5-1 together with the normal BLM5 allele was sufficient to produce mitotic and meiotic defects in diploids, and greatly increase killing by bleomycin beyond wild type levels. Mitotic growth rates of blm5-1/blm5-1 homozygous mutant strains were slower than wild type or BLM5/blm5-1 heterozygous strains at 30 degrees C, and growth was nearly completely inhibited at 37 degrees C. Meiosis was inhibited at 30 degrees C and 37 degrees C in mutant homozygotes, and at 37 degrees C in BLM5/blm5-1 heterozygotes, while meiosis occurred at equivalent frequencies in wild type strains at both temperatures. Surprisingly, mutant strains were found to associate extremely low quantities of [S-methyl-3H]bleomycin A2, in contrast to normal strains that associated quite high amounts. However, the fractions of the total associated radioactivities that were released from normal and blm5-1 cells were equivalent. These results suggested that the extremely high killing suffered by blm5-1 mutant strains in response to bleomycin treatments results from something other than increased intracellular drug concentrations.     

Life table study of Sitotroga cerealella (Lepidoptera: Gelichiidae), a strain from West Africa

Life table studies for the Angoumois grain moth, Sitotroga cerealella (Olivier), a pest on stored maize, Zea mays L., in West Africa, were conducted as part of the expansion of a mathematical simulation model that has been developed for two pests of stored maize. The effects of four temperatures (20, 25, 30, and 35 degrees C) and two relative humidity levels (44 and 80%) on developmental time, age-specific survivorship and fecundity, sex ratio, and intrinsic rate of natural increase (r(m)) of S. cerealella were investigated. Sex ratio was close to 1:1 at all temperatures and humidity. Minimum development time occurred close to 32 degrees C and 80% RH for both males and females, and developmental time of females was significantly shorter than that of males. Immature survivorship was highest between 25 and 30 degrees C and 80% RH and lowest at 35 degrees C under both humidity conditions. A similar low level was found at 20 degrees C and 44% RH. The greatest fecundity (124 eggs per female) occurred at 20 degrees C, 80% RH. The maximum r(m) value was 0.086 d(-1) at 30 degrees C and 80% RH, but the growth rate declined dramatically at 35 degrees C. If compared with the few other life table studies conducted on this species on maize in India and North America, some variation among the strains becomes evident. A common conclusion for the current study and previous ones is that optimal population development for S. cerealella occurs at approximately 30 degrees C and at high humidity.     

Effect of incubation temperature on zearalenone production by strains of Fusarium crookwellense.

After 6 weeks incubation on rice 2 strains of Fusarium crookwellense produced more zearalenone (6060-5010 mg/kg dry wt of culture) at ambient temperature (16-29 degrees C) in daylight than at ambient temperature (18-23 degrees C) in darkness or at controlled temperatures of 11 degrees C, 20 degrees C or 25 degrees C in darkness. Yields at 25 degrees C were low. Incubation at 11 degrees C during the second 3 weeks incubation increased yields only when preliminary incubation had been at 25 degrees C. After 6 weeks incubation at controlled temperatures in darkness, 4 strains produced most zearalenone at 20 degrees C (2460-21 360 mg/kg), 1 strain at 11 degrees C (6570 mg/kg). Yields at a temperature oscillating daily from 10-20 degrees C were less than at 15 degrees C. One of the 5 strains produced appreciable amounts of a-zearlaenol (1645 mg/kg at 20 degrees C) and 2 of nivalenol (340 and 499 mg/kg at 20 degrees C).     

Isolation and properties of barophilic and barotolerant bacteria from deep-sea mud samples

Several barophilic and barotolerant bacteria were isolated from deep-sea mud samples of Suruga Bay (2485 m depth), the Ryukyu Trench (5110 m depth), and the Japan Trench (land-side 6356 m, and sea-side 6269 m depth, respectivelys. The barophilic bacteria, strains DB5501, DB6101, DB6705 and DB6906, were albe to grow better under high hydrostatic pressures than under atmospheric pressure (0.1 megapascals; MPa). The optimal growth pressures for the barophilic bacteria were approximately 50 MPa at 10°C. The barotolerant strains DSK1 and DSS12 were determined to be psychrophilic, and had optimal growth temperatures of 10°C and 8°C, respectively. The degree of barophily and barotolerance was shown to be very dependent on temperature. For example, at 4°C the barophilic strains were indistinguishable from barotolerant bacteria, whereas at 15°C the barotolerant strains behaved more like the barophilic strains. Based on sequence analysis of 16S ribosomal DNA, all of the strains included in this study belong to the gamma subgroup of the Proteobacteria. Phylogenetic relations between the isolated strains and the known gamma subgroup bacteria suggested that the isolated strains belong to a new sub-branch of this group.     

Minimum growth temperatures of Listeria monocytogenes and non-haemolytic Listeria

Minimum growth temperatures and those of decreased growth were determined for 100 strains of listerias. The ability of 78 strains of Listeria monocytogenes isolated from animals and 22 non-haemolytic strains to grow at low temperatures was studied, using a flooding technique, in a plate-type continuous temperature gradient incubator at temperatures between -1.6 and 14.5 degrees C. The mean minimum temperature for L. monocytogenes was +1.7 +/- 0.5 degrees C. The growth of non-haemolytic listerias was unobservable at +1.7 +/- 0.5 degrees C. The L. monocytogenes strains grew at about 0.6 degrees C lower than the non-pathogenic strains. No differences in growth temperatures were observed among L. monocytogenes strains isolated from different sources. The serovars with the OI antigen grew at lower temperatures (+1.0 +/- 0.3 degrees C) than the other common serovar 4b (+1.3 +/- 0.4 degrees C). The results indicate that L. monocytogenes grows better than non-haemolytic strains under cold conditions. The possible role of haemolysins as growth factors is also discussed.