The occurrence of antibiotic resistant and metal tolerant coliform organisms was investigated in unpolluted upstream and polluted downstream Gomati River water. Increased levels of antibiotic resistance were found among downstream thermotolerant coliforms which included many multiple antibiotic-resistant (MAR) strains. Transmissibility of antibiotic resistance was demonstrated in 55.7% of MAR isolates and the rate of transfer was between 1.36×10-4 and 1.8×10-11. Upstream coliform isolates were more tolerant to aluminium and copper than downstream isolates. Downstream coliform isolates exhibited tolerance to mercury which occurred frequently among MAR strains. The isolation rate of MAR coliforms and mercury-tolerant MAR strains was highest during the winter months.
The polyphenol oxidase from Chaetomium thermophile Isolate O-453 was examined for its substrate specificity. The purified enzyme acted on polyphenols but not on monophenols. Among the polyphenols and phenol-like compounds tested, those oxidized were d-catechin (relative activity, 100%), l-epicatechin (95.3%), chlorogenic acid (80.0%), pyrocatechol (53.8%), DOPamine (47.8%), guaiacol (87.5%), and N, N-dimethyl-p-phenylenediamine (75.3%). Esculine (7.8%), resorcinol (0%), p-quinone (0%), o-phenylenediamine (1.3%), phenol (0%), and L-tyrosine (0%) were scarcely oxidized. The purified enzyme was inhibited by potassium xanthogenate, thiourea, cysteine, potassium cyanide, and sodium azide. Mercuric and ferrous ions inactivated the enzyme. Carbon monooxide did not inhibit the activity (residual activity, 92.0%). SDS-polyacrylamide gel electrophoresis showed that the purified enzyme (mw, 98, 000) is a trimer composed of three of the same kinds of monomers (mw, 36, 000). These data indicate that the polyphenol oxidase from C. thermophile Isolate O-453 is a copper-containing protein and is classified as laccase [benzenediol: oxygen oxidoreductase, EC 126.96.36.199].
Chromosomal DNAs from medically important Candida species were separated by pulse-field gel electrophoresis (PFGE). The banding patterns of 2 to 6 strains from individual species were examined for comparison. Variations occurred in the number of bands and their positions in the gel, not only among strains of different species but also among strains from the same species. However, some degrees of species-specific banding patterns were recognized. In C. krusei and C. guilliermondii, each banding pattern was similar to that of its relevant teleomorph. The phenomenon of colony-morphology switching occurred in most of those Candida species and, in some cases, the number of chromosomal bands varied in relation to the phenomenon.
The chemotactic response of bacteria to extracellular products of two bloom algae, Asterionella glacialis (Bacillariophycea) and Chattonella marina (Rhaphidophycea) was measured using the quantitative capillary tube technique. Genus Vibrio did not show chemotactic response to either algal extracellular product. Pseudomonas 022 which was isolated as a dominant bacterium during the A. glacialis bloom was chemotactic to A. glacialis extracellular product, but not to C. marina extracellular product. The chemotactic response of Pseudomonas 022 was great when the bacterium was preincubated on A. glacialis extracellular product. The chemotactic substance(s) in the extracellular product of A. glacialis has a molecular weight in the range 5, 000-1, 000 daltons with cationic charge and is composed by amino acids.
Anaerobic digestion of sewage sludge of municipal wastewater was investigated using inhibitors to determine the relationship between methanogenesis and sulfate reduction. During anaerobic incubation of the sludge without inhibitors, CH4 was actively produced, and there were no volatile fatty acids, the intermediary products of anaerobic degradation of organic matter, in the sludge. Inhibition of methanogenesis by chloroform resulted in the accumulation of H2 and volatile fatty acids such as acetate and propionate. Adding sulfate to the sludge did not affect CH4 production, but there was much sulfate reduction. In the sulfate- supplemented sludge, the inhibition of methanogenesis also caused acetate accumulation, but not the longer-chain fatty acids or H2. Inhibition of sulfate reduction by molybdate did not affect either CH4 production or the concentrations of the intermediary products. But the inhibition of both methanogenesis and sulfate reduction caused the accumulation of acetate, longer-chain fatty acids and H2. These results indicate that the enhancement of sulfate reduction in the sludge is supported by the acceleration of electron flow in the ecosystem and apparently does not retard methanogenesis.
An emendation of the diagnosis of the ballistospore-forming yeast genus Bensingtonia Ingold is proposed to permit the inclusion of yeasts forming pigmented colonies and curved ballistospores. This genus is characterized by Q-9 as the major ubiquinone component and the lack of xylose in the cell walls. The following six new combinations are proposed: Bensingtoniaintermedia (Nakase et Suzuki) Nakase et Boekhout, Bensingtonia miscanthi (Nakase et Suzuki) Nakase et Boekhout, Bensingtonia naganoensis (Nakase et Suzuki) Nakase et Boekhout, Bensingtonia subrosea (Nakase et Suzuki) Nakase et Boekhout, Bensingtonia yamatoana (Nakase, Suzuki et Itoh) Nakase et Boekhout and Bensingtonia yuccicola (Nakase et Suzuki) Nakase et Boekhout. A key to the species is given.
By adding low-concentration antimony(III), production of streptolysin S in growing streptococci was arrested immediately, but cellular growth and production of extracellular nucleases were not particularly affected. Streptococci incubated with antimony(III) for 4h still contained a significant amount of intracellular streptolysin S. Antimony(III) also blocked the toxin formation in the resting cells and this inhibition was counteracted by a sulfhydryl compound such as cysteine or dithiothreitol.