Isolation and characterization of a new strain of Methanothermobacter marburgensis DX01 from hot springs in China.

Strain DX01, a thermophilic methanogen, was isolated from a hot spring in China. Strain DX01 grew only on H2/CO2. The DNA G+C content is 52 mol% and optimal growth temperature is 65 degrees C. The cell pellet is brick red. By analyzing 16S rRNA sequence, methyl-coenzyme M reductase I, gamma subunit protein sequences, we determined the DX01 strain to be closely related to the species of Methanothermobacter marburgensis. In addition, Methanothermobacter thermautotrophicus delta H(T) and strain DX01 had clear differences in their biochemical composition and protein expression profiles. Based on the above analysis, we propose that strain DX01 is a novel strain within thermoautotrophicus the species of M. marburgensis, namely M. marburgensis DX01. The isolation and characterization of the new M. marburgensis DX01 strain expands the known range of the Methanothermobacter genus.

Bacterial degradation of anthraquinone dyes.

Anthraquinone dyes, which contain anthraquinone chromophore groups, are the second largest class of dyes after azo dyes and are used extensively in textile industries. The majority of these dyes are resistant to degradation because of their complex and stable structures; consequently, a large number of anthraquinone dyes find their way into the environment causing serious pollution. At present, the microbiological approach to treating printing and dyeing wastewater is considered to be an economical and feasible method, and reports regarding the bacterial degradation of anthraquinone dyes are increasing. This paper reviews the classification and structures of anthraquinone dyes, summarizes the types of degradative bacteria, and explores the possible mechanisms and influencing factors of bacterial anthraquinone dye degradation. Present research progress and existing problems are further discussed. Finally, future research directions and key points are presented.

Influences of quinclorac on culturable microorganisms and soil respiration in flooded paddy soil.

OBJECTIVE: To investigate the potential effects of herbicide quinclorac (3,7-dichloro-8-quinoline-carboxylic) on the culturable microorganisms in flooded paddy soil. METHODS: Total soil aerobic bacteria, actinomycetes and fungi were counted by a 10-fold serial dilution plate technique. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN) methods with anaerobic liquid enrichment media. The number of methanogenic bacteria (MB) and nitrogen-fixing bacteria (NFB) was determined by the rolling tube method in triplicate. Soil respiration was monitored by a 102G-type gas chromatography with a stainless steel column filled with GDX-104 and a thermal conductivity detector. RESULTS: Quinclorac concentration was an important factor affecting the populations of various culturable microorganisms. There were some significant differences in the aerobic heterotrophic bacteria. AFB and DNB between soils were supplemented with quinclorac and non-quinclorac at the early stage of incubation, but none of them was persistent. The number of fungi and DNB was increased in soil samples treated by lower than 1.33 micro x g(-1) dried soil, while the CFU of fungi and HPAB was inhibited in soil samples treated by higher than 1.33 microg x g(-1) dried soil. The population of actinomycete declined in negative proportion to the concentrations of quinclorac applied after 4 days. However, application of quinclorac greatly stimulated the growth of AFB and NFB. MB was more sensitive to quinclorac than the others, and the three soil samples with concentrations higher than 1 microg x g(-1) dried soil declined significantly to less than 40% of that in the control, but the number of samples with lower concentrations of quinclorac was nearly equal to that in the control at the end of experiments. CONCLUSION: Quinclorac is safe to the soil microorganisms when applied at normal concentrations (0.67 microg x g(-1)).

Characterization and phylogenetic analysis of a phenanthrene-degrading strain isolated from oil-contaminated soil.

Bacterium strain EVA17 was isolated from an oil-contaminated soil, and identified as Sphingomonas sp. based on analysis of 16S rDNA sequence, cellular fatty acid composition and physiological-chemical tests. The salicylate hydroxylase and catechol 2, 3-dioxygenase (C230) were detected in cell-free lysates, suggesting a pathway for phenanthrene catabolism via salicylate and catechol. Alignment showed that both of the C230 and GST genes of the strain EVA17 had high similarity with homologues of strains from genus Sphingomonas. The phylogenetic analysis based on 16S rDNA and C230 gene sequence indicated that EVA17 should be classified into genus Sphingomonas, although the two phylogenetic trees were slightly different from each other. The results of coamplification and sequence determination indicated that GST gene should be located upstream of the C230 gene.

Studies on biosorption equilibrium and kinetics of Cd2+ by Streptomyces sp. K33 and HL-12.

The sorption of Cd(2+) by Streptomyces sp. K33 and HL-12 was investigated. The removal efficiency increased with pH, but no obvious differences with different temperatures. Fourier transform infrared (FT-IR) was used to characterize the interaction between Cd(2+) and K33 and HL-12. Results revealed that the presence of amino, carboxyl, hydroxyl and carbonyl groups were responsible for the biosorption of Cd(2+). Strain HL-12 had more changes in the functional groups than K33. Biosorption equilibrium was established earlier by strain K33 than that by HL-12, and K33 had higher adsorption ratio. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms were used to describe the adsorption experiment, Langmuir model fitted the experiment data best. Strain K33 showed greater sorption capacities with 38.49 mg Cd(2+)/g dry cells. Pseudo-first-order and second-order kinetic models were used to describe the kinetic data, and second-order kinetic model fitted better. About 70% recovery of Cd(2+) could be obtained at pH

[Contribution of anaerobic oxidation of methane to whole methane oxidation].

The contribution of anaerobic methane oxidation to the whole methane oxidation is investigated by monitoring the activities of anaerobic and aerobic oxidation of methane in paddy soils composed mechanically of <0.02 mm and > 0.02 mm soil granules, contained different water contents, and long-term fertilized organic manure or inorganic nitrogen, phosphorus and potassium fertilizers. The results obtained from various treated soils are relatively identical, which shows that most of the activities of anaerobic methane oxidation is obviously lower than those of aerobic methane oxidation. The contribution of anaerobic methane oxidation was generally lower than 10% of total methane oxidation in paddy soils with different treatments, however, higher than 30% in the soils emerged in water as the soils became anaerobic and methane diffused difficultly into soil, leading to lower activity of aerobic methane oxidation. The long-term fertilization has a significant effect on the activity of aerobic methane oxidation in paddy soil, with the / t / > t0.05, P < 0.05, but a slightly one with ( / t / < t 0.05, p > 0.05), leading to the obvious influence on the emission flux of methane. The contribution rates of anaerobic methane oxidation were lower from 1.31% to 4.14% in the whole methane oxidation.