Metabolism of 3-methylindole by a methanogenic consortium.

A methanogenic 3-methylindole (3-MI)-degrading consortium, enriched from wetland soil, completely mineralized 3-MI. Degradation proceeded through an initial hydroxylation reaction forming 3-methyloxindole. The consortium was unable to degrade oxindole or isatin, suggesting a new pathway for 3-MI fermentation.     

Metabolism of 3-methylindole by a methanogenic consortium.

A methanogenic 3-methylindole (3-MI)-degrading consortium, enriched from wetland soil, completely mineralized 3-MI. Degradation proceeded through an initial hydroxylation reaction forming 3-methyloxindole. The consortium was unable to degrade oxindole or isatin, suggesting a new pathway for 3-MI fermentation.     

Carboxylation of o-cresol by an anaerobic consortium under methanogenic conditions.

The metabolism of o-cresol under methanogenic conditions by an anaerobic consortium known to carboxylate phenol to benzoate was investigated. After incubation with the consortium at 29 degrees C for 59 days, o-cresol was transformed to 3-methylbenzoic acid, which was not further metabolized by the consortium. Proteose peptone in the culture medium was essential for the transformation of o-cresol. In addition, a transient compound detected in the culture was identified as 4-hydroxy-3-methylbenzoic acid. o-Cresol-6d was transformed by the consortium to deuterated hydroxy-methylbenzoic acid and deuterated methylbenzoic acid. These results demonstrate that o-cresol is carboxylated in the para position relative to the phenolic hydroxyl group and dehydroxylated by the anaerobic consortium.     

Carboxylation of o-cresol by an anaerobic consortium under methanogenic conditions.

The metabolism of o-cresol under methanogenic conditions by an anaerobic consortium known to carboxylate phenol to benzoate was investigated. After incubation with the consortium at 29 degrees C for 59 days, o-cresol was transformed to 3-methylbenzoic acid, which was not further metabolized by the consortium. Proteose peptone in the culture medium was essential for the transformation of o-cresol. In addition, a transient compound detected in the culture was identified as 4-hydroxy-3-methylbenzoic acid. o-Cresol-6d was transformed by the consortium to deuterated hydroxy-methylbenzoic acid and deuterated methylbenzoic acid. These results demonstrate that o-cresol is carboxylated in the para position relative to the phenolic hydroxyl group and dehydroxylated by the anaerobic consortium.     

Transformation of Phenol into Phenylalanine by a Methanogenic Consortium

The conversion by a methanogenic consortium of phenol into phenylalanine, with benzoic and phenylpropionic acid as intermediates, was investigated. When (sup14)C-labelled phenol was fed to the consortium, the radioactivity was mostly transferred into methane and CO(inf2), but 4% of the radioactivity was found in the water fraction after extraction of the culture medium with an organic solvent. Utilization of labelled compounds and analysis by gas chromatography coupled with mass spectrometry revealed that a fraction of the benzoic acid produced was transformed into 3-phenylpropionic acid. When fully (sup13)C-labelled acetic acid was fed to the consortium, the labels were incorporated at the 1 and 2 positions of 3-phenylpropionic acid. When deuterium-labelled 3-phenylpropionic acid was fed to the consortium, part of the phenylalanine of the biomass was labelled. These metabolic transformations are reversible, since deuterium-labelled phenylalanine generated labelled 3-phenylpropionic acid. Cinnamic acid was also transformed into 3-phenylpropionic acid.     

降解尿酸乳酸菌复合菌系的筛选与菌株组合提升降解效果

【背景】高尿酸症由血液中尿酸含量明显升高而导致,利用乳酸菌对人体的益生作用缓解高尿酸血症越来越受到关注。【目的】获得具有降解尿酸能力的乳酸菌复合菌系与纯培养菌株。【方法】以泡菜为样品来源,以尿酸为底物,采用MRS培养基筛选降解尿酸的乳酸菌复合菌系,通过高效液相色谱法测定复合菌系对尿酸的降解能力。【结果】得到一组乳酸菌复合菌系,当培养温度为37 °C、pH值为6.20、静置培养72 h后复合菌系对尿酸的降解率为12.08%;通过优化培养条件,当该菌系在以牛肉膏为单一氮源、初始pH值为5.00、温度为35 °C的条件下培养72 h,尿酸降解率上升至17.19%,降解率比优化前提高了42.3%;从该菌系中分离出两株具有尿酸降解能力的菌株UA-1与UA-2,它们的尿酸降解率分别为10.85%和8.65%;通过形态学观察和16S rRNA基因序列分析,经鉴定两株菌均为布氏乳杆菌(Lactobacillus buchneri)。将两株单菌组合降解尿酸试验发现,UA-1与UA-2比例为2:1的尿酸降解率为20.2%,比原复合菌系的降解能力提高了67.22%。【结论】研究证明了乳酸菌复合菌系对尿酸的降解能力优于单个菌株,为后续利用乳酸菌复合菌系应用提供了数据支持。     

Anaerobic Phenol Degradation by Microorganisms of Swine Manure

Swine manure contains diverse groups of aerobic and anaerobic bacteria. An anaerobic bacterial consortium containing sulfate-reducing bacteria (SRB) and acetate-utilizing methanogenic bacteria was isolated from swine manure. This consortium used phenol as its sole source of carbon and converted it to methane and CO₂. The sulfate-reducing bacterial members of the consortium are the incomplete oxidizers, unable to carry out the terminal oxidation of organic substrates, leaving acetic acid as the end product. The methanogenic bacteria of the consortium converted the acetic acid to methane. When a methanogen inhibitor was used in the culture medium, phenol was converted to acetic acid by the SRB, but the acetic acid did not undergo further metabolism. On the other hand, when the growth of SRB in the consortium was suppressed with a specific SRB inhibitor, namely, molybdenum tetroxide, the phenol was not degraded. Thus, the metabolic activities of both the sulfate-reducing bacteria and the methanogenic bacteria were essential for complete degradation of phenol. Received: 31 January 1997 / Accepted: 7 March 1997     

Enantioselective degradation of the herbicide mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid] by mixed and pure bacterial cultures

Abstract A consortium of three bacteria was isolated from top soil through their capacity to utilise the chlorinated, aromatic herbicide mecoprop as a single growth substrate. The consortium constituted a tight association of Alcaligenes denitrificans, Pseudomonas glycinea and Pseudomonas marginalis . The culture exclusively degraded the ( R )-(+)-isomer of the herbicide while the ( S )-(−)-enantiomer remained unaffected. The mecoprop-degrading community could also degrade 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid and racemic 2-phenoxypropionic acid. Initially, no single member of the consortium was able to degrade mecoprop as a pure culture but after prolonged incubation, A. denitrificans was able to grow on the herbicide as the sole source of carbon and energy.     

复合乳酸菌对冷藏海鲈鱼块的保鲜效果

【目的】研究复合乳酸菌对冷藏海鲈鱼块的保鲜效果。【方法】以冷藏海鲈鱼块为对象,筛选出3株能够明显抑制其优势腐败菌(草莓假单胞菌Pseudomonas fragi,腐败希瓦氏菌Shewanella putrefacens)生长的单一乳酸菌,同时也筛选出对其优势腐败菌具有最显著抑制效果的一组复合乳酸菌,再将该复合乳酸菌接种到海鲈鱼块上,在4°C冷藏过程中,通过感官评定、挥发性盐基氮(TVB-N值)的测定和优势腐败菌的计数来评价复合乳酸菌对冷藏海鲈鱼块的保鲜效果。【结果】单一乳酸菌(干酪乳杆菌LC1、植物乳杆菌LP1和乳酸菌L3)对2株冷藏海鲈鱼优势腐败菌的抑制效果明显;复合乳酸菌(干酪乳杆菌LC1+植物乳杆菌LP1+乳酸菌L3)的抑菌效果最为显著;在4°C冷藏过程中,复合乳酸菌能使冷藏海鲈鱼块发生感官变化延缓6 d、使TVB-N值的升高延缓2 d,同时显著抑制优势腐败菌的生长。【结论】复合乳酸菌对冷藏海鲈鱼块具有良好的保鲜作用,能有效延长其货架期。     

中度嗜盐菌群对酸性大红GR的脱色性能研究

【目的】获得能够在高盐环境下脱色偶氮染料的高效脱色菌群,应用于印染废水的生物处理。【方法】采用在5%盐度培养基富集的方法,从印染废水的活性污泥中富集能够在5%盐度下脱色酸性大红GR的嗜盐混合菌群,利用高通量测序方法研究其群落结构,利用静置培养的方法研究其脱色性能。【结果】该菌群可以在5%盐度、静置培养下15 h内将100 mg/L的酸性大红GR几乎完全脱色,主要由Halomonas、Salinicoccus、Nitratireductor和Aequorivita等4个属组成,Halomonas是主要的脱色菌。高浓度的Na NO_3、Na_2SO_4和Na Cl抑制菌群的脱色,其中Na NO_3抑制作用最强。该菌群的最佳脱色条件是在p H 7.0、盐度5%、30°C脱色效果最好,可脱色直接耐黑G和分散深蓝S-3BG等偶氮染料,并且具有连续脱色的能力。【结论】嗜盐菌群在处理偶氮染料废水中具有良好的应用价值。     

Changes in the composition of an acid mine drainage microbial community upon successive transfers in medium containing low-grade copper sulfide

A consortium of microorganisms from acid mine drainage samples was cultured in modified 9 K medium containing low-grade copper sulfide. The culture was maintained for sixty days and then transferred to fresh medium. This process was repeated three more times and a final consortium exhibiting a copper extraction rate of 89.3% was obtained. RFLP and microarrays analysis of 16S rRNA sequences retrieved from the consortia showed that Acidithiobacilluscaldus, Leptospirillumferriphilum, Sulfobacillus sp., Acidiphilium sp., and Sulfolobus spp. were represented in higher numbers in the consortia obtained in the copper-containing medium than in the original consortium. In contrast, a decrease in Acidithiobacillus ferrooxidans, Alicyclobacillus sp., Pseudomonas sp., and Sulfobacillus thermosulfidooxidans was observed. The abundance of genes related to sulfur metabolism from At. caldus and Sulfolobus spp., iron oxidation from Leptospirillum sp. and metal resistance from most of the detected microorganisms increased as the consortium was successively transferred into fresh medium.     

Mineralization of Diethylthiophosphoric Acid by an Enriched Consortium from Cattle Dip

Enrichment cultures were initiated from cattle dip solution with diethylthiophosphoric acid (DETP) as the carbon and energy source. An enriched consortium consisting of at least six distinct bacterial species was subsequently obtained. The consortium mineralized DETP to sulfate and phosphate while utilizing ethyl moieties as a carbon and energy source. These data demonstrate that DETP can be metabolized under environmentally realistic conditions.     

Metabolism of the 18O-methoxy substituent of 3-methoxybenzoic acid and other unlabeled methoxybenzoic acids by anaerobic bacteria.

O-methyl substituents of aromatic compounds can provide C1 growth substrates for facultative and strict anaerobic bacteria isolated from diverse environments. The mechanism of the bioconversion of methoxylated benzoic acids to the hydroxylated derivatives was investigated with a model substrate and cultures of one anaerobic consortium, eight strict anaerobic bacteria, and one facultative anaerobic microorganism. Using high-pressure liquid chromatography and gas chromatography-mass spectral analysis, we found that a haloaromatic dehalogenating consortium, a dehalogenating isolate from that consortium, Eubacterium limosum, and a strain of Acetobacterium woodii metabolized 3-[methoxy-18O]methoxybenzoic acid (3-anisic acid) to 3-[hydroxy-18O]hydroxybenzoic acid stoichiometrically at rates of 1.5, 3.2, 52.4, and 36.7 nmol/min per mg of protein, respectively. A different strain of Acetobacterium and strains of Syntrophococcus, Clostridium, Desulfotomaculum, Enterobacter, and an anaerobic bacterium, strain TH-001, were unable to transform this compound. The O-demethylating ability of E. limosum was induced only with appropriate methoxylated benzoates but not with D-glucose, lactate, isoleucine, or methanol. Cross-acclimation and growth experiments with E. limosum showed a rate of metabolism that was an order of magnitude slower and showed no growth with either 4-methoxysalicylic acid (2-hydroxy-4-methoxybenzoic acid) or 4-anisic acid (4-methoxybenzoic acid) when adapted to 3-anisic acid. However, A. woodii NZva-16 showed slower rates and no growth with 3- or 4-methoxysalicylic acid when adapted to 3-anisic acid in similar experiments. The results clearly indicate a methyl rather than methoxy group removal mechanism for such reactions.     

Metabolism of the 18O-methoxy substituent of 3-methoxybenzoic acid and other unlabeled methoxybenzoic acids by anaerobic bacteria

O-methyl substituents of aromatic compounds can provide C1 growth substrates for facultative and strict anaerobic bacteria isolated from diverse environments. The mechanism of the bioconversion of methoxylated benzoic acids to the hydroxylated derivatives was investigated with a model substrate and cultures of one anaerobic consortium, eight strict anaerobic bacteria, and one facultative anaerobic microorganism. Using high-pressure liquid chromatography and gas chromatography-mass spectral analysis, we found that a haloaromatic dehalogenating consortium, a dehalogenating isolate from that consortium, Eubacterium limosum, and a strain of Acetobacterium woodii metabolized 3-[methoxy-18O]methoxybenzoic acid (3-anisic acid) to 3-[hydroxy-18O]hydroxybenzoic acid stoichiometrically at rates of 1.5, 3.2, 52.4, and 36.7 nmol/min per mg of protein, respectively. A different strain of Acetobacterium and strains of Syntrophococcus, Clostridium, Desulfotomaculum, Enterobacter, and an anaerobic bacterium, strain TH-001, were unable to transform this compound. The O-demethylating ability of E. limosum was induced only with appropriate methoxylated benzoates but not with D-glucose, lactate, isoleucine, or methanol. Cross-acclimation and growth experiments with E. limosum showed a rate of metabolism that was an order of magnitude slower and showed no growth with either 4-methoxysalicylic acid (2-hydroxy-4-methoxybenzoic acid) or 4-anisic acid (4-methoxybenzoic acid) when adapted to 3-anisic acid. However, A. woodii NZva-16 showed slower rates and no growth with 3- or 4-methoxysalicylic acid when adapted to 3-anisic acid in similar experiments. The results clearly indicate a methyl rather than methoxy group removal mechanism for such reactions.     

Ability of a Microbial Consortium to Remove Pesticide,Carbendazim and 2,4-Dichlorophenoxyacetic Acid

A bacterial consortium capable of simultaneously degrading the fungicide, carbendazim, and the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D) was obtained by enrichment of soil samples collected from paddy fields in Japan. This consortium was acclimated in a continuously fed culture with 20 M carbendazim and 2 mM 2,4-D as sole carbon sources using a glass column reactor. By denaturing gradient gel electrophoresis, we observed changes in the bacterial population following the degradation of the both pesticides. This acclimated consortium completely degraded up to 100 M carbendazim and 3 mM 2,4-D within 36 and 24 h, respectively, in batch culture, but a lag time was observed after precultivation in a rich medium. The immobilization of the consortium on a polyester support enhanced the degradation ability of this consortium compared with the use of free cells. This microbial consortium could be useful for bioremediation at sites contaminated with these pesticides.     

Chlorinated biphenyl mineralization by individual populations and consortia of freshwater bacteria

Comparative studies were performed to investigate the contribution of microbial consortia, individual microbial populations, and specific plasmids to chlorinated biphenyl biodegradation among microbial communities from a polychlorinated biphenyl-contaminated freshwater environment. A bacterial consortium, designated LPS10, was shown to mineralize 4-chlorobiphenyl (4CB) and dehalogenate 4,4'-dichlorobiphenyl. The LPS10 consortium involved three isolates: Pseudomonas testosteroni (LPS10A), which mediated the breakdown of 4CB and 4,4'-dichlorobiphenyl to 4-chlorobenzoic acid; an isolate tentatively identified as an Arthrobacter sp. (LPS10B), which mediated 4-chlorobenzoic acid degradation; and Pseudomonas putida bv. A (LPS10C), whose role in the consortium has not been determined. None of these isolates contained detectable plasmids or sequences homologous to the 4CB-degradative plasmid pSS50. A freshwater isolate, designated LBS1C1, was found to harbor a 41-megadalton plasmid that was related to the 35-megadalton plasmid pSS50, and this isolate was shown to mineralize 4CB. In chemostat enrichments with biphenyl and 4CB as primary carbon sources, the LPS10 consortium was found to outcomplete bacterial populations harboring plasmids homologous to pSS50. These results demonstrate that an understanding of the biodegradative capacity of individual bacterial populations as well as interacting populations of bacteria must be considered in order to gain a better understanding of polychlorinated biphenyl biodegradation in the environment.     

Chlorinated biphenyl mineralization by individual populations and consortia of freshwater bacteria.

Comparative studies were performed to investigate the contribution of microbial consortia, individual microbial populations, and specific plasmids to chlorinated biphenyl biodegradation among microbial communities from a polychlorinated biphenyl-contaminated freshwater environment. A bacterial consortium, designated LPS10, was shown to mineralize 4-chlorobiphenyl (4CB) and dehalogenate 4,4'-dichlorobiphenyl. The LPS10 consortium involved three isolates: Pseudomonas testosteroni (LPS10A), which mediated the breakdown of 4CB and 4,4'-dichlorobiphenyl to 4-chlorobenzoic acid; an isolate tentatively identified as an Arthrobacter sp. (LPS10B), which mediated 4-chlorobenzoic acid degradation; and Pseudomonas putida bv. A (LPS10C), whose role in the consortium has not been determined. None of these isolates contained detectable plasmids or sequences homologous to the 4CB-degradative plasmid pSS50. A freshwater isolate, designated LBS1C1, was found to harbor a 41-megadalton plasmid that was related to the 35-megadalton plasmid pSS50, and this isolate was shown to mineralize 4CB. In chemostat enrichments with biphenyl and 4CB as primary carbon sources, the LPS10 consortium was found to outcomplete bacterial populations harboring plasmids homologous to pSS50. These results demonstrate that an understanding of the biodegradative capacity of individual bacterial populations as well as interacting populations of bacteria must be considered in order to gain a better understanding of polychlorinated biphenyl biodegradation in the environment.     

Selection and isolation of bacteria capable of degrading dinoseb (2-sec-buty-4,6-dinitrophenol)

Dinoseb (2-sec-butyl-4,6-dinitrophenol) has been a widely used herbicide that persists in some contaminated soils, and has been found in groundwaters, causing health and environmental hazards. Persistence in some soils may stem from a lack of dinoseb-degrading organisms. We established a chemostat environment that was strongly selective for aerobic (liquid phase) and anaerobic (sediment phase) bacteria able to degrade dinoseb. The chemostat yielded five taxonomically diverse aerobic isolates that could transform dinoseb to reduced products under microaerophilic or denitrifying conditions, but these organisms were unable to degrade the entire dinoseb molecule, and the transformed products formed multimeric material. The chemostat also yielded an anaerobic consortium of bacteria that could completely degrade dinoseb to acetate and CO₂ when the Eh of the medium was less than-200 mV. The consortium contained at least three morphologically different bacterial species. HPLC analysis indicated that dinoseb was degraded sequentially via several as yet unidentified products. Degradation of these intermediates was inhibited by addition of bromoethane sulfonic acid. GC-MS analysis of metabolites in culture medium suggested that regiospecific attacks occurred non-sequentially on both the nitro groups and the side-chain of dinoseb. The consortium was also able to degrade 4,6-dinitro-o-cresol, 3,5-dinitrobenzoic acid, 2,4-dinitrotoluene, and 2,6-dinitrotoluene via a similar series of intermediate products. The consortium was not able to degrade 2,4-dinitrophenol. To our knowledge, this is the first report of strictly anaerobic biodegradation of an aromatic compound containing a multicarbon, saturated hydrocarbon side chain.Abbreviations BESA bromoethane sulfonic acid - RAMM reduced anaerobic mineral medium     

Biofilm establishment and heavy metal removal capacity of an indigenous mining algal-microbial consortium in a photo-rotating biological contactor

An indigenous mining algal-microbial consortium was immobilised within a laboratory-scale photo-rotating biological contactor (PRBC) that was used to investigate the potential for heavy metal removal from acid mine drainage (AMD). The microbial consortium, dominated by Ulothrix sp., was collected from the AMD at the Sar Cheshmeh copper mine in Iran. This paper discusses the parameters required to establish an algal-microbial biofilm used for heavy metal removal, including nutrient requirements and rotational speed. The PRBC was tested using synthesised AMD with the multi-ion and acidic composition of wastewater (containing 18 elements, and with a pH of 3.5?±?0.5), from which the microbial consortium was collected. The biofilm was successfully developed on the PRBC's disc consortium over 60?days of batch-mode operation. The PRBC was then run continuously with a 24?h hydraulic residence time (HRT) over a ten-week period. Water analysis, performed on a weekly basis, demonstrated the ability of the algal-microbial biofilm to remove 20-50?% of the various metals in the order Cu?>?Ni?>?Mn?>?Zn?>?Sb?>?Se?>?Co?>?Al. These results clearly indicate the significant potential for indigenous AMD microorganisms to be exploited within a PRBC for AMD treatment.     

Use of Fluorinated Compounds To Detect Aromatic Metabolites from m-Cresol in a Methanogenic Consortium: Evidence for a Demethylation Reaction

Anaerobic sewage sludge was used to enrich a methanogenic m-cresol-degrading consortium. 6-Fluoro-3-methylphenol was synthesized and added to subcultures of the consortium with m-cresol. This caused the accumulation of 4-hydroxy-2-methylbenzoic acid. In a separate experiment, the addition of 3-fluorobenzoic acid caused the transient accumulation of 4-hydroxybenzoic acid. Inhibition with bromoethanesulfonic acid caused the accumulation of benzoic acid. Thus, the proposed degradation pathway was m-cresol → 4-hydroxy-2-methylbenzoic acid → 4-hydroxybenzoic acid → benzoic acid. The m-cresol-degrading consortium was able to convert exogenous 4-hydroxybenzoic acid and benzoic acid to methane. In addition, for each metabolite of m-cresol identified, the corresponding fluorinated metabolite was detected, giving the following sequence: 6-fluoro-3-methylphenol → 5-fluoro-4-hydroxy-2-methylbenzoic acid → 3-fluoro-4-hydroxybenzoic acid → 3-fluorobenzoic acid. The second step in each of these pathways is a novel demethylation which was rate limiting. This demethylation reaction would likely facilitate the transformation of the methyl group to methane, which is consistent with the results of a previous study that showed that the methyl carbon of m-[methyl-¹⁴C]cresol was recovered predominantly as [¹⁴C]methane (D. J. Roberts, P. M. Fedorak, and S. E. Hrudey, Can. J. Microbiol. 33:335-338, 1987). The final aromatic compound in the proposed route for m-cresol metabolism was benzoic acid, and its detection in these cultures merges the pathway for the methanogenic degradation of m-cresol with those for the anaerobic metabolism of many phenols.