Biodegradation of the mixture of 2,4,6-trichlorophenol, 4-chlorophenol,and phenol by a defined mixed culture

Two new strains, Pseudomonas sp. TCP114 degrading 2,4,6-trichlorophenol (TCP) and Arthrobacter sp. CPR706 degrading 4-chlorophenol (4-CP), were isolated through a selective enrichment procedure. Both strains could also degrade phenol. The degradability of one component by a pure culture was strongly affected by the presence of other compounds in the medium. For example, when all three components (TCP, 4-CP, and phenol) were present in the medium, a pure culture of CPR706 could not degrade any of the components present. This restriction on degradability could be overcome by employing a defined mixed culture of the two strains. The mixed culture could degrade all three components in the mixture through cooperative activity. It was also demonstrated that the mixed culture could be immobilized by using calcium alginate for the semi-continuous degradation of the three-component mixture. Immobilization not only accelerates the degradation rate, but also enables reuse of the cell mass several times without losing the cells' degrading capabilities.     

Degradation of phenanthrene,fluorene and fluoranthene by pure bacterial cultures

Summary Bacterial mixed cultures able to degrade the polycyclic aromatic hydrocarbons (PAH) phenanthrene, fluorene and fluoranthene, were obtained from soil using conventional enrichment techniques. From these mixed cultures three pure strains were isolated:Pseudomonas paucimobilis degrading phenanthrene;P. vesicularis degrading fluorene andAlcaligenes denitrificans degrading fluoranthene. The maximum rates of PAH degradation ranged from 1.0 mg phenanthrene/ml per day to 0.3 mg fluoranthene/ml per day at doubling times of 12 h to 35 h for growth on PAH as sole carbon source. The protein yield during PAH degradation was about 0.25 mg/mg C for all strains. Maximum PAH oxidation rates and optimum specific bacterial growth were obtained near pH 7.0 and 30°C. After growth entered the stationary phase, no dead end-products of PAH degradation could be detected in the culture fluid.     

Investigation of the biodegradation of pentachlorophenol by the predominant bacterial strains in a mixed culture

A pentachlorophenol (PCP) degrading mixed culture contained three predominant strains identified as Flavobacterium gleum, Agrobacterium radiobacter and Pseudomonas sp. The relative abilities of the three strains to degrade PCP were tested individually and in combination. Rates of PCP degradation by individual isolates were lower than that observed for the three isolates combined. Of the individual strains, Flavobacterium gleum manifested highest PCP degradation ability. A biodegradation medium inoculated with a combination of the three isolates exhibited PCP degradation patterns similar to the original mixed culture. Varying low amounts of tetrachlorophenol were found in degradation medium inoculated with individual isolates, but this intermediate was absent from media inoculated with the mixed culture.     

Symbiotic Utilization of Polyvinyl Alcohol by Mixed Cultures

Polyvinyl alcohol (PVA)-utilizing cultures were obtained from various sources. They were mixed cultures even after cyclical transfer to liquid and plate media with PVA as a sole source of carbon. Component bacteria were isolated from the several mixed cultures, and it was shown that PVA was utilized symbiotically by two bacterial members which could not utilize PVA in each respective pure culture. From a mixed culture, strains VM15, VM15A (Pseudomonas putida) and VM15C (Pseudomonas sp.) were isolated as members essential for PVA utilization. VM15C was the predominant strain in the mixed-culture population and produced PVA-degrading enzyme. The culture supernatant of VM15A enabled VM15C to grow on PVA. VM15A was presumed to supply VM15C with a unique growth stimulant which was distinct from usual growth factors.     

Isolation and characterization of a bacterium which utilizes polyester polyurethane as a sole carbon and nitrogen source

Abstract Various soil samples were screened for the presence of microorganisms which have the ability to degrade polyurethane compounds. Two strains with good polyurethane degrading activity were isolated. The more active strain was tentatively identified as Comamonas acidovorans . This strain could utilize polyester-type polyurethanes but not the polyether-type polyurethanes as sole carbon and nitrogen sources. Adipic acid and diethylene glycol were probably the main degradation products when polyurethane was supplied as a sole carbon and nitrogen source. When ammonium nitrate was used as nitrogen source, only diethylene glycol was detected after growth on polyurethane.     

Response of a chlorophenols degrading mixed culture to changing loads of phenol,chlorophenol and cresols

Summary A phenol and solvents degrading mixed culture from soil and sludge supplemented with Pseudomonas sp. strain B13 which harbors genes coding the sequence for chlorocatechol breakdown was acclimated to monochlorophenol degradation. Pyrocatechase activity was used as an indicator for the adaptation status of the culture.In the fully acclimated culture, strain B13 was partially replaced by hybrid strains which had acquired the chlorocatechol degrading sequence. This culture degraded changing loads of phenol, chlorophenols and cresols without accumulation of DOC (dissolved organic carbon). When high cresol concentrations were supplied simultaneously with the chlorophenols, strains were enriched which degrade cresols and 3-methylbenzoate via ortho-cleavage pathway.     

Biodegradation of triazine herbicides on polyvinylalcohol gel plates by the soil yeast Lipomyces starkeyi

The soil yeast Lipomyces starkeyi was tested for its ability to degrade triazine herbicides. Polyvinylalcohol (PVA) was employed as a solid medium in culture plates instead of agar. The cell sizes of the control (without nitrogen source) on the PVA gel plate were much smaller than those on the agar gel plate. The difference between the diameters of the sample and control colonies on the PVA gel plate were almost twice those of the colonies on the agar gel plate (1.9 and 1.0 mm, respectively). Thus, the PVA gel plate is much better than the agar plate for evaluating the degree of utilization of a sole nitrogen source. The yeast grew well (more than 4 mm in diameter) with 1,3,5-triazine or cyanuric acid as nitrogen source. In addition, melamine and thiocyanuric acid inhibited growth of the yeast, and the sizes of colonies were smaller than those of the control. All triazine herbicides tested (simazine, atrazine, cyanazine, ametryn, and prometryn) could be degraded and assimilated by L. starkeyi.     

Total biodegradation of the oestrogenic mycotoxin zearalenone by a bacterial culture

A mixed culture of bacteria, enriched from soil collected at a coal gasification site, proved capable of removing the potent oestrogenic mycotoxin zearalenone from culture media. The bacteria grew rapidly when zearalenone was provided as the sole source of carbon and energy. HPLC and ELISA analysis of culture extracts revealed no zearalenone or zearalenone-like products. Fourteen bacterial isolates from the mixed culture were identified and purified. The ability to degrade zearalenone was lost upon purification and recombination of the bacterial members of the mixed culture. A strain of Pseudomonas fluorescens capable of degrading polychlorinated biphenyls was unable to degrade zearalenone. This is the first report of the complete degradation of zearalenone by bacteria. The present study suggests the potential of mixed cultures in the biodegradation of zearalenone.     

Total degradation of 6-aminonaphthalene-2-sulphonic acid by a mixed culture consisting of different bacterial genera

Abstract A mixed bacterial culture consisting of eleven different strains was investigated in view of its ability to degrade 6-aminonaphthalene-2-sulphonic acid (6A2NS). Taxonomic characterization of the microorganisms showed that they belonged to three genera: Flavobacterium, Bacillus and Pseudomonas . None of the single strains could degrade 6A2NS. Some of 4–5-member co-cultures degraded it, but lost the ability in future subcultures. Only the mixed culture consisting of all eleven strains were stable and efficacious in degradation through numerous subcultures. The well-adapted mixed culture degraded the compound fast and without accumulation of intermediates, with a low increase in cell biomass and a high degree of mineralization.     

Utilization of capsaicin and vanillylamine as growth substrates by Capsicum (hot pepper)-associated bacteria

Capsaicin contributes to the organoleptic attributes of hot peppers. Here, we show that capsaicin is utilized as a growth nutrient by certain bacteria. Enrichment cultures utilizing capsaicin were successfully initiated using Capsicum-derived plant material or leaves of tomato (a related Solanaceae) as inocula. No other sources of inoculum examined yielded positive enrichments. Of 25 isolates obtained from enrichments: all utilized 8-methylnonanoic acid; nine were found capable of degrading capsaicin as sole carbon and energy source; 11 were found capable of utilizing vanillylamine; but only two strains could use either of these latter two compounds as sole nitrogen source. Phylogenetic analysis of capsaicin degraders revealed them to be strains of Variovorax and Ralstonia, whereas the vanillylamine degraders were strains of Pseudomonas and Variovorax. Neither of the two strains isolated from one enrichment culture originally inoculated with dried pepper fruit was capable of using capsaicin as sole carbon and nitrogen source. However, good growth was achieved under such conditions when the two isolates, a strain of Variovorax paradoxusThat degraded capsaicin when provided with ammonium, and a vanillylamine degrading strain of Pseudomonas putida, were cultured together. A cross-feeding of capsaicin-derived carbon and nitrogen between members of pepper-associated consortia is proposed.     

Mixed culture of nitrifying bacteria and denitrifying bacteria for simultaneous nitrification and denitrification

A mixed culture containing nitrifying bacteria and denitrifying bacteria was investigated for aerobic simultaneous nitrification and denitrification. A mixture of NaHCO₃ and CH₃COONa was selected as the appropriate carbon source for cell growth and nitrogen removal, the concentrations of carbon and nitrogen sources were also examined. Ammonia could be oxidized aerobically to nitrite by the mixed culture, and the intermediate nitrite was then reduced to dinitrogen gas. No nitrite was detected during the process. 0.212 g of ammonia/l could be removed in 30 h and nitrate could not be utilized aerobically by the mixed culture. Nitrite could be degraded aerobically as well as anaerobically. Very little ammonia was degraded anaerobically, but the ability to degrade ammonia could be recovered even after oxygen had been supplied for 42 h.     

Factors influencing the ability of Pseudomonas putida strains epI and II to degrade the organophosphate ethoprophos

Two strains of Pseudomonas putida (epI and epII), isolated previously from ethoprophos-treated soil, were able to degrade ethoprophos (10 mg 1(-1)) in a mineral salts medium plus nitrogen (MSMN) in less than 50 h with a concurrent population growth. Addition of glucose or succinate to MSMN did not influence the degrading ability of Ps. putida epI, but increased the lag phase before rapid degradation commenced with Ps. putida epII. The degrading ability of the two isolates was lost when the pesticide provided the sole source of phosphorus. Degradation of ethoprophos was most rapid when bacterial cultures were incubated at 25 and 37 degrees C. Pseudomonas putida epI was capable of completely degrading ethoprophos at a slow rate at 5 degrees C, compared with Ps. putida epII which could not completely degrade ethoprophos at the same time. Pseudomonas putida epI was capable of degrading ethoprophos when only 60 cells ml(-1) were used as initial inoculum. In contrast, Ps. putida epII was able to totally degrade ethoprophos when inoculum densities of 600 cells ml(-1) or higher were used. In general, longer lag phases accompanied the lower inoculum levels. Both isolates rapidly degraded ethoprophos in MSMN at pHs ranging from 5.5 to 7.6, but not at pH 5 or below.     

The utilization of morpholine as a sole nitrogen source by Gram-negative bacteria

The ability of Gram-negative bacteria to degrade morpholine when growing in pure culture is reported for the first time. Several bacterial strains were able to degrade morpholine and to utilize it as a sole nitrogen source but not as a sole carbon and energy source. The organisms studied were obtained from river water and activated sludge and could not be isolated directly on morpholine-containing media which always yielded growth of Gram-positive bacteria using morpholine as a carbon and energy source. The Gram-negative strains were isolated on the basis of their ability to grow on the structurally-related heterocyclc amines piperidine and pyrrolidine.     

Secretion of keratinolytic enzymes and keratinolysis by Scopulariopsis brevicaulis and Trichophyton mentagrophytes: regression analysis

A survey on keratinophilic fungi from poultry-farm soils at Namakkal and from feather dumping soils at Chennai, India, revealed the existence of 34 species of fungi. Most of the fungi exhibited variable efficiency in producing extracellular keratinase when grown in plates with chicken feathers as the sole carbon and nitrogen source. The fungi Aspergillus flavus, Aspergillus niger, Aspergillus versicolor, Chrysosporium state of Arthroderma tuberculatum, Paecilomyces carneus, Scopulariopsis brevicaulis, Trichoderma viride, and Trichophyton mentagrophytes were efficient candidates to degrade the feathers. However, when cultivating the strains in submerged conditions in a medium containing chicken feathers as the sole nutrients source, Aspergillus glaucus, Chrysosporium keratinophilum, Curvularia lunata, Fusarium solani, and Penicillium citrinum also proved to be potent. Among all species, S. brevicaulis and Trichophyton mentagrophytes produced higher amounts of keratinase in both methods. Conditions for keratinase production were optimized by statistical design and surface plots. The highest keratinase activity was estimated by S. brevicaulis (3.2 KU/mL) and Trichophyton mentagrophytes (2.7 KU/mL) in the culture medium with chicken feathers and shows (79% and 72.2% of degrading ability, respectively).     

除草剂二甲戊灵的真菌降解及其特性研究

富集分离了除草剂二甲戊灵降解真菌,并研究了其降解特性,结果表明,真菌可以降解二甲戊灵,利用富集培养的方法从环境中分离到16株能降解二甲戊灵的真菌。其中10株真菌5d内对100mg·L^-1二甲戊灵的降解率大于60％,以其中3株生理耐受能力强、降解能力高的真菌为例,研究了外加碳源浓度、初始pH值、二甲戊灵浓度和培养温度对真菌生长量和降解能力的影响,此3株真菌经鉴定分别属于土生曲霉组(Aspergillus terreus)、长梗串孢霉属(Monilochaetes)和烟色曲霉组(Aspergillus furnigatus),在外加碳源浓度为0．5％～1．0％的范围内,真菌生长量和降解率达到最大;在中性培养液中,3株真菌的生长量大,降解能力强;在浓度为100mg·L^-1时降解率和生长量都比较大,而绝对去除量随二甲戊灵浓度的提高而增加,在500mg·L^-1时达到最大;真菌的生长和降解需要适宜的温度,20～30℃培养时,降解率和生长量最大,可为农药污染治理及生产污水处理提供理论依据。     

Investigation of the biotransformation of pentachlorophenol and pulp paper mill effluent decolorisation by the bacterial strains in a mixed culture

Mixed culture of two bacterial strains Bacillus sp. and Serratia marcescens showed potential pentachlorophenol (PCP) degradation and decolorisation of pulp paper mill effluent. The physico-chemical quality of pulp paper mill effluent has been analyzed after 168 h incubation period degraded by mixed culture. The study revealed that it has decreased high load of BOD, COD, TS, TDS, TSS, sulphate, phosphate, total nitrogen, total phenols, metals and different salts (i.e. chloride, sodium, nitrate, potassium) at 168 h incubation period. PCP degradation in pulp paper mill effluent was confirmed by HPLC analysis. Mixed culture was found to degrade PCP up to (94%) present in pulp paper mill effluent with 1% glucose and 0.5% peptone (w/v) at 30 ± 1 °C, pH 8.0 ± 0.2 at 120 rpm in 168 h incubation period. The simultaneous release of chloride ion up to 1200 mg/l at 168 h emphasized the bacterial dechlorination in the medium. The pulp paper mill effluent degradation was also supported by decline in pH, AOX (absorbable organic halides), color, D.O., BOD, COD and PCP. The analysis of pulp paper mill effluent degradation products by GC–MS analysis revealed the formation of low molecular weight compound like 2-chlorophenol (RT = 3.8 min) and tetrachlorohydroquinone (RT = 11.86 min) from PCP extracted degraded sample. Further, mixed culture may be used for bioremediation of PCP containing pulp paper mill waste in the environment.     

Degradation and mineralization of 3-chlorobiphenyl by a mixed aerobic bacterial culture

Summary A mixed bacterial culture obtained from polychlorinated-biphenyl-contaminated river sediments proved capable of degrading 3-chlorobiphenyl (3-CB) under aerobic laboratory conditions. Almost total mineralization of 150 mg/l of 3-CB occurred when, after 3 days of incubation, the mineral medium was supplied with benzoic acid as a carbon source. Two strains of Pseudomonas capable of degrading the substrate to 3-chlorobenzoic acid and a strain of Pseudomonas fluorescens capable of co-metabolizing this metabolite were selected from the mixed culture. A nearly stoichiometric amount of chloride, which defines the percentage of total mineralization, was eliminated during mixed culture growth. Offprint requests to: F. Fava     

海带发酵降解中相关海洋功能菌的分离、鉴定与筛选

目的 从海带养殖环境中筛选有效降解海带的海洋功能菌,对海带进行降解处理,提高利用率,增加海带原料价值。方法 采用以果胶或海藻酸钠为唯一碳源的选择性培养基挑选含有果胶酶、褐藻酸裂解酶的菌株;测定海带发酵液中海藻酸含量,复筛降解效果好的单菌及复合菌;16S rDNA测序对菌种进行鉴定。结果 使用含10%鲜海带的富集培养基培养48 h,其中降解效果较好的为1-2和3-10菌种的组合,其降解量为95%。结论 经上述研究选出有效的降解海带功能菌1-2和3-10,其降解海带效果较好,对海带利用率高。     

多环芳烃降解菌的筛选、鉴定及降解特性

【目的】多环芳烃(PAHs)是一类普遍存在于环境中且具有高毒性的持久性有机污染物,高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。研究拟从供试菌株中筛选多环芳烃高效降解菌,并分析其降解特性,为多环芳烃污染环境的微生物修复提供资源保障和科学依据。【方法】采用平板法从25株供试菌株中筛选出以菲和芘为唯一碳源和能源的高效降解菌,经16S rRNA基因序列进行初步鉴定,通过单因素实验法分析其在液体培养基中的降解特性。【结果】筛选出的3株多环芳烃高效降解菌SL-1、02173和02830经16S rRNA基因序列分析,02173和02830分别与假单胞菌属中的Pseudomonas alcaliphila和Pseudomonas corrugate同源性最近,SL-1为本课题组发表新类群Rhizobium petrolearium的模式菌株;降解实验表明,菌株SL-1 3 d内对单一多环芳烃菲(100 mg/L)和芘(50 mg/L)的降解率分别达到100%和48%,5 d后能够降解74%的芘;而其3 d内对混合PAHs中菲和芘的降解率分别为75.89%和81.98%。菌株02173和02830 3 d内对混合多环芳烃中萘(200 mg/L)、芴(50 mg/L)、菲(100 mg/L)和芘(50 mg/L)的降解率均分别超过97%。【结论】筛选出的3株PAHs降解菌SL-1、02173和02830不仅可以高效降解低分子量PAHs,还对高分子量PAHs具有很好的降解潜力。研究表明,由于共代谢作用低分子量多环芳烃可促进高分子量多环芳烃的降解,而此时低分子量多环芳烃的降解将受到抑制。     

Enrichment, isolation, and characterization of 4-chlorophenol-degrading bacterium Rhizobium sp. 4-CP-20

The objectives of this research were to monitor the variations of species in mixed cultures during the enrichment period, isolate species and identify and characterize the pure 4-chlorophenol (4-CP) degrading strains from enriched mixed cultures. Strain Rhizobium sp. 4-CP-20 was isolated from the acclimated mixed culture. The DGGE result indicated that strain Rhizobium sp. 4-CP-20 was undetectable at the beginning but detectable after 2 weeks of enrichment. The optimum growth temperatures for Rhizobium sp. 4-CP-20 were both 36°C using 350 mg l⁻¹ glucose or sodium acetate as the substrate. The optimum pH range for degrading 100 mg l⁻¹ 4-CP was between 6.89 and 8.20. Strain Rhizobium sp. 4-CP-20 could degrade 4-CP completely within 3.95 days, as the initial 4-CP concentration was 100 mg l⁻¹. If the initial 4-CP concentration was higher than 240 mg l⁻¹, the growth of bacterial cells and the activity of degrading 4-CP were both inhibited.