Effect of sulfate and nitrate on anaerobic degradation of volatile fatty acids at 20°C was investigated. Acetate degradation was found to be independent of the presence of sulfate. The addition of sulfate enhanced propionate/butyrate/valerate oxidation with acetate accumulation. Sulfate appreciably inhibited 14CH4 production from H2+14CO2 only in the absence of an exogenous electron donor. The sulfate-reducing bacterial counts on propionate increased 10-fold in the presence of sulfate compared to control. Whereas, molybdate and nitrate decreased the volatile fatty acids degradation and methane production by inhibiting both SRB and methanogens.
A Gram-negative, aerobic bacterium isolated from the bottom layer of Lake Vanda, Antarctica, can grow in a synthetic medium containing biotin as a growth factor. The lipid and fatty acid compositions of the cells grown in the fatty acid-free medium were analyzed. Phosphatidylethanolamine, phosphatidylglycerol and wax esters were identified as major components of the chloroform-methanol extractable lipids. Palmitoleic and oleic acids comprised more than 90% of the total fatty acid of the lipids when the bacterium was grown at low temperature (5°C). Increasing the growth temperature induced an increase in the average fatty acyl chain length of the phospholipids and a decrease in the unsaturation degree of the fatty acyl chain of the wax esters. Increasing the NaCl concentration in the medium also induced an increase in the average fatty acyl chain length of the phospholipids. The effects of temperature and NaCl were compared further at the level of phospholipid molecular species. The sn-2 position of phosphatidylethanolamine and the sn-1 position of phosphatidylglycerol were the most sensitive sites to changes of temperature and NaCl concentration, respectively. An aerobic desaturase system was demonstrated to be the only pathway for unsaturated fatty acid synthesis in this bacterium.
Two strains, E4 and E7 of Xenorhabdus nematophilus were used to examine the effect of bacterial age and culture method on the physicochemical properties of the bacteria, the production of flagella, fimbriae, and outer membrane proteins, and subsequently, the adhesion of the bacteria to hemocytes of the insect Galleria mellonella. The patterns of removal of the bacteria from the hemolymph in vivo mediated by the hemocytes varied with the bacterial strain, age and culture method. The cells of both strains in the stationary phase in shaken culture tubes and flasks were more extensively removed by nodule formation than were bacteria in the early and late exponential growth phases. The level of granular cells with adhering bacteria in the hemocyte monolayers in vitro increased with increasing bacterial age for both strains. The in vivo and in vitro hemocyte responses were independent of bacterial hydrophobicity and electrostatic charge but were correlated with bacterial viability. Bacterial metabolites released into culture media did not affect the relationship between bacterial viability and hemocyte contact. Bacterial surface features influenced hemocyte responses. The glycocalyx did not mediate adhesion to hemocytes.
Iron uptake mechanisms were investigated in strains of Vibrio parahaemolyticus with different serotypes. Although the production of siderophore was detected in all the strains tested, they were not able to grow in the presence of high concentrations of the iron chelator EDDHA but were able to grow in the presence of only low concentrations of EDDHA (ranging from lower than 8 to 64μM). Two iron-repressible outer membrane proteins (IROMPs) with molecular weights of 71, 000 (71K protein) and 72, 000 (72K protein) were produced in the strain 3283-61 grown in iron-deficient medium. Kinetic analysis revealed that the 71K and 72K proteins occurred 1.5 and 2.5h, respectively, after downshift from chemically defined medium to iron-deficient medium. Analysis of IROMPs from V. parahaemolyticus strains with different serotypes showed that the patterns of IROMPs from these strains were very similar to that of strain 3283-61: all the strains produced the two IROMPs of 71K and 72K proteins, except one strain, which produced only the 71K protein.
Accumulation of alien chemicals which cannot be assimilated creates toxicity both for those flora and fauna and for humans who eat fish which feed on them. Phenol is one such chemical that causes alarm by this process of accumulation. The difficulty with the treatment of phenol is that it can inhibit microbial growth at relatively low concentrations of 200 mg/l. Hence, removal of phenol from industrial aqueous effluents is an important practical problem. A mutant strain of Pseudomonas pictorum was isolated after extensive screening and the necessary cultural parameters were studied. The results indicated that the selected mutant strain, designated as MU 174, could degrade 2.0g/l phenol in about 33h at a pH and temperature of 7-9 and 30-34°C, respectively. More than 0.05% glucose showed a repressive effect. In addition to the degradation of phenol, it could degrade resorcinol, 2- and 4-chlorophenol. MU 174 was effective in treating phenolic wastewater in the presence of sewage medium.
Growth temperatures, fermentation characteristics and electrophoretic karyotype of sixteen strains of Saccharomyces bayanus and nine strains of Saccharomyces cerevisiae were examined. Growth temperatures of 1 and 2°C accompanied by 35°C clearly distinguished these two species, and also fermentation characteristics, such as fermentation velocity at a low temperature (7°C) and ethanol yield for fermentation at an intermediate temperature (28°C), supported this distinction. Additionally, in pulsed- field gel electrophoresis under the conditions for separating large DNA molecules, specific chromosomal bands were observed in each of the two species. From these results, it was concluded that growth temperatures and electrophoretic karyotyping were convenient tools for practical discrimination of the two species.
The influence of in vivo growth on the surface characteristics of Aeromonashydrophila serotype 0:34 was examined. Strain L57 was grown in rainbow trout muscle by infecting animals at a localized site. The method permitted an easy recovery of the strain in pure culture and a good bacterial yield. Transmission electron microscopy showed the presence of capsule-like material on the surface of the cells grown in vivo but not on the cells grown in vitro. In our experimental conditions, Western blots showed a lack of antigenic differences between the LPS synthesized in vivo and in vitro.