Volatilization of mercury compounds and utilization of various aromatic compounds by a broad-spectrum mercury resistant Bacillus pasteurii strain

Abstract: The hydrocarbon utilizing haloarchaea, Haloferax (two strains), Halobacterium and Halococcus from a hypersaline coastal area of the Arabian Gulf, had the potential for resistance and volatilization of Hg(2+). Individual haloarchaea resisted up to between 100 and 200 ppm HgCl₂ in hydrocarbon free media with salinities between 1 and 4 M NaCl, but only up to between 20 and 30 ppm in a mineral medium containing 3 M NaCl, with 0.5% (w/v) crude oil, as a sole source of carbon and energy. Halococcus and Halobacterium volatilized more mercury than Haloferax. The individual haloarchaea consumed more crude oil in the presence of 3 M NaCl than in the presence of 2 M NaCl. At both salinities, increasing the HgCl₂ concentration in the medium from 0 to 20 ppm resulted in decreasing the oil consumption values by the individual haloarchaea. However, satisfactory oil consumption still occurred in the presence of 10 ppm HgCl₂. It was concluded that haloarchaea with the combined potential for mercury resistance and volatilization and hydrocarbon consumption could be useful in removing toxic mercury forms effectively from oil free, mercury contaminated, hypersaline environments, and mercury and oil, albeit less effectively, from oily hypersaline environments.

Abstract: The mercuric ion reduction system encoded by the Hg2+ inducible mer operon confers bacterial resistance to mercuric ion. The mer A gene product which is a FAD-containing enzyme catalyzes the reduction of Hg2+ to volatile elemental mercury with the help of intracellular thiols and NADPH as a cofactor (Schottel 1974; Summers and Silver 1978; Fox and Walsh 1982; Misra 1992). Our earlier studies have shown that growing cells of different mercury-resistant bacteria reduce Hg2+ compounds to Hg(O) (Ray et al. 1989; Pahan et al. 1990a; Gachhui et al. 1989). We have also shown the effect of thiol compounds and flavins on mercury-degrading enzyme activities in mercury-resistant bacteria (Pahan et al. 1990b). Here we report that resting cells of mercury-resistant bacteria survive in a buffer system for several hours, synthesize inducible mercury-degrading enzymes and volatilize mercury from a mercury-containing buffer system. We know of no information regarding studies of mercury-degrading enzymes in resting mercury-resistant bacterial cells.

Abstract: 112. Sundb?ck, K., et al, "Influence of Sublittoral Microphytobenthos on the Oxygen and Nutrient Flux Between Sediment and Water: A Laboratory Continuous-flow Study." Mar. Ecol. Prog. Ser. (Ger.), 74,263(1991). 113. Sweerts, J.-P. R. A., et al, "Oxygen-consuming Processes at the Profundal and Littoral Sediment-Water Interface of a Small Meso eutrophic Lake (Lake Vechten, The Netherlands)." Limnol. Oceanogr., 36, 1124(1991). 114. Fiebig, D. M., and Lock, M. A., "Immobilization of Dissolved Organic Matter From Groundwater Discharging Through the Stream Bed." Freshwater Biol. (G. B.), 26, 45 ( 1991 ). 115. Shearer, C. A., and Webster, J., "Aquatic Hyphomycete Com munities in the River Teign. IV. Twig Colonization." Mycol. Res., 95,413(1991). 116. Czeczuga, B., "Studies of Aquatic Fungi. Part 16: Aquatic Fungi of the River Pisa and Its Tributary, the River Skroda." Acta Hy drochim. HydrobioL (Ger.), 19, 57 ( 1991 ). 117. Thomas, K., et al, "Changes in Concentration of Aquatic Hypho mycete Spores in Lees Creek, ACT, Australia." Mycol. Res., 95, 178(1991). 118. Thomas, K., et al, "A Dynamic Model of Fungal Spora in a Fresh water Stream." Mycol. Res., 95, 184 ( 1991 ). 119. B?rlocher, F., "Intraspecific Hyphal Interactions Among Aquatic Hyphomycetes." Mycologia, 83, 82 ( 1991 ). 120. B?rlocher, F., "Fungal Colonization of Fresh and Dried Leaves in the River Teign (Devon, England)." Nova Hedwigia (Ger.), 52, 349(1991). 121. Gessner, M. O., and Schwoerbel, J., "Fungal Biomass Associated with Decaying Leaf Litter in a Stream." Oecologia (Ger.), 87,602 (1991). 122. Chergui, H, and Pattee, E., "An Experimental Study of the Break down of Submerged Leaves by Hyphomycetes and Invertebrates in Morocco." Freshwater Biol. (G. B.), 26, 97 ( 1991 ). 123. Christian, R. R., and Wetzel, R. L., "Synergism Between Research and Simulation Models of Estuarine Microbial Food Webs." Mi crob. Ecol, 22, 111 (1991). 124. Lane, D. J., et al, "Evolutionary Relationships Among Sulfurand Iron-oxidizing Eubacteria." J. BacterioL, 174, 269 (1991). 125. Rahat, M., "An Ecological Approach to Hydra-cell Colonization by Algae-Algae/Hydra Symbioses." Oikos ( Den.), 62,381 ( 1991 ). 126. Vacelet, E., and Thomassin, B. A., "Microbial Utilization of Coral Mucus in Long Term In Situ Incubation Over a Coral Reef." Hy drobiologia (Neth.), 211, 19 ( 1991 ). 127. Uriz, M. J., et al, "An Approach to the Ecological Significance of Chemically Mediated Bioactivity in Mediterranean Benthic Com munities." Mar. Ecol Prog. Ser. (Ger.), 70, 175 ( 1991 ).

Abstract: Microbial responses to chemicals manifest themselves in a variety of forms depending on the chemical, the type of microorganism, the concentration, the exposure time, and other chemical, physical, biological, and environmental factors. Barriers to quantifying the effects of chemicals on microorganisms are frequently related to methodological or analytical limitations. Recent developments in methodologies used to evaluate chemical-microbial interactions are summarized in this paper. A brief overview of recent studies on microbial responses to specific chemicals is provided in tabular form categorized by chemical and microorganism.

Abstract: A broad spectrumbroad spectrum mercury-resistant organism, Bacillus pasteurii DR 2 , was isolated from the effluents of Durgapur Steel Plant, India. In the presence of phenylmercuric acetate or benzene the rate of glucose uptake and the level of some metabolic enzymes increased significantly. Inhibition of the glucose oxidation rate by these chemicals in lysozyme-treated cells indicated that these compounds facilitated the transport of glucose across the cell wall and thereby stimulated growth

Abstract: Aromatic compounds of both natural and man-made sources abound in the environment. The degradation of such chemicals is mainly accomplished by microorganisms. This review provides key background information but centres on recent developments in the bacterial degradation of selected man-made aromatic compounds. An aromatic compound can only be considered to be biodegraded if the ring undergoes cleavage, and this is taken as the major criteria for inclusion in this review (although the exact nature of the enzymic ring-cleavage has not been confirmed in all cases discussed).

Abstract: BIOTRANSFORMA nONS OF TOXIC MET AL CAnONS . Mercury . The mercury cycle in the biosphere .. Biological methylation of mercury . Microbial resistance to mercury and organomercurials .

Abstract: The degradation of pyrene, a polycyclic aromatic hydrocarbon containing four aromatic rings, by pure cultures of a Mycobacterium sp. was studied. Over 60% of [14C]pyrene was mineralized to CO2 after 96 h of incubation at 24 degrees C. High-pressure liquid chromatography analyses showed the presence of one major and at least six other metabolites that accounted for 95% of the total organic-extractable 14C-labeled residues. Analyses by UV, infrared, mass, and nuclear magnetic resonance spectrometry and gas chromatography identified both pyrene cis- and trans-4,5-dihydrodiols and pyrenol as initial microbial ring-oxidation products of pyrene. The major metabolite, 4-phenanthroic acid, and 4-hydroxyperinaphthenone and cinnamic and phthalic acids were identified as ring fission products. 18O2 studies showed that the formation of cis- and trans-4,5-dihydrodiols were catalyzed by dioxygenase and monooxygenase enzymes, respectively. This is the first report of the chemical pathway for the microbial catabolism of pyrene.

Abstract: A Pseudomonas species able to degrade p-dichlorobenzene as the sole source of carbon and energy was isolated by selective enrichment from activated sludge. The organism also grew well on chlorobenzene and benzene. Washed cells released chloride in stoichiometric amounts from o-, m-, and p-dichlorobenzene, 2,5-dichlorophenol, 4-chlorophenol, 3-chlorocatechol, 4-chlorocatechol, and 3,6-dichlorocatechol. Initial steps in the pathway for p-dichlorobenzene degradation were determined by isolation of metabolites, simultaneous adaptation studies, and assay of enzymes in cell extracts. Results indicate that p-dichlorobenzene was initially converted by a dioxygenase to 3,6-dichloro-cis-1,2-dihydroxycyclohexa-3,5-diene, which was converted to 3,6-dichlorocatechol by an NAD+-dependent dehydrogenase. Ring cleavage of 3,6-dichlorocatechol was by a 1,2-oxygenase to form 2,5-dichloro-cis, cis-muconate. Enzymes for degradation of haloaromatic compounds were induced in cells grown on chlorobenzene or p-dichlorobenzene, but not in cells grown on benzene, succinate, or yeast extract. Enzymes of the ortho pathway induced in cells grown on benzene did not attack chlorobenzenes or chlorocatechols.