白腐菌在固体培养基下对吲哚和吡啶的降解

研究了稻草秆粉介质中白腐菌对吲哚和吡啶的降解.实验结果表明,质量浓度分别为200、80 mg/L左右的吲哚可被白腐菌去除99%以上,质量浓度为74 mg/L吡啶的去除率为61.5%;白腐菌在稻草秆粉培养体系中对吲哚和吡啶的降解,符合零级反应动力学,其中反应速率常数K(高浓度吲哚)＞K(低浓度吲哚)＞K(吡啶);高低浓度吲哚和吡啶3个降解体系的漆酶活力在第6天达到最大;漆酶在吲哚和吡啶降解过程中起着较重要的作用,但酶活的变化与吲哚和吡啶的相对去除率不呈线性相关,稻草秆粉培养基中的介质和培养环境在降解过程中可能也起着重要作用.     

Biodegradation of the herbicide glyphosate by filamentous fungi in platform shaker and batch bioreactor

The biodegradation conducted by microorganisms on herbicide glyphosate (N-phosphonomethylglycine) was investigated. Five strains of filamentous fungi belonging to the Fusarium genre were grown on Czapeck medium without phosphorous and supplemented with the addition of glyphosate. The assays were conducted to determine the ability of use as a phosphorous source, the inhibition caused by presence of herbicide, and the biodegradation in shaker and bioreactor by Fusarium strains. It was observed that the herbicide did not show any negative effect on microrganisms by quantity of the biomass. Among the strains tested, no inhibition was noted by the addition of glyphosate even at a high concentration. All strains studied were able to biodegrade it and use the herbicide as a phosphorous source. The formation of consortium was not better than the strains tested in pure culture. The biodegradation in the bioreactor was better than in the shaker. However, there wasn't any influence on biodegradation rate by changing the amount of oxygen in the system.     

Simultaneous biodegradation of bifenthrin and chlorpyrifos by Pseudomonas sp. CB2

The degradation of bifenthrin (BF) and chlorpyrifos (CP), either together or individually, by a bacterial strain (CB2) isolated from activated sludge was investigated. Strain CB2 was identified as belonging to genus Pseudomonas based on the morphological, physiological, and biochemical characteristics and a homological analysis of the 16S rDNA sequence. Strain CB2 has the potential to degrade BF and CP, either individually or in a mixture. The optimum conditions for mixture degradation were as follows: OD_600nm = 0.5; incubation temperature = 30°C; pH = 7.0; BF-CP mixture (10 mg L^?1 of each). Under these optimal conditions, the degradation rate constants (and half-lives) were 0.4308 d^?1 (1.61 d) and 0.3377 d^?1 (2.05 d) for individual BF and CP samples, respectively, and 0.3463 d^?1 (2.00 d) and 0.2931 d^?1 (2.36 d) for the BF-CP mixture. Major metabolites of BF and CP were 2-methyl-3-biphenylyl methanol and 3,5,6-trichloro-2-pyridinol, respectively. No metabolite bioaccumulation was observed. The ability of CB2 to efficiently degrade BF and CP, particularly in a mixture, may be useful in bioremediation efforts.     

Antifungal efficacy of some natural phenolic compounds against significant pathogenic and toxinogenic filamentous fungi

In terms of food safety, species of the Fusarium, Aspergillus and Penicillium genera are considered the most significant because they produce the great majority of known mycotoxins. Developing resistance against commonly used fungicides have become a critical problem in area such as agriculture, the storage and production of food and even in human medicines. The need for research and development of new alternative antifungal treatment based on natural antifungal substances is obvious. Here, the antifungal efficacy of 21 phenolic components of essential oils and plant substances were tested against these filamentous fungi with respect to their different molecular structures. Minimum inhibitory concentration values MIC₅₀ and MIC₁₀₀ were successfully estimated for 15 substances by means of probit analysis. Thymol and carvacrol were evaluated as the most effective. The MIC₅₀ values for thymol ranged from 30 to 52 μg mL⁻¹. The MIC₁₀₀ values for thymol ranged from 76 to 255 μg mL⁻¹, respectively. For carvacrol, the MIC₅₀ values ranged from 37 to 76 μg mL⁻¹, and the MIC₁₀₀ ranged from 131 to 262 μg mL⁻¹. The results also revealed differences in the efficacy of phenols depending on molecular structures and different inter-species sensitivity.     

Biodegradation of Methoxychlor and Its Metabolites by the White Rot Fungus Stereum hirsutum Related to the Inactivation of Estrogenic Activity

The white rot fungus Stereum hirsutum was used to degrade methoxychlor [2,2,2-trichloro-1,1-bis(4-methoxyphenyl)ethane] in culture and the degraded products were extensively determined. The estrogenic activity of the degraded products of methoxychlor was examined using cell proliferation and pS2 gene expression assays in MCF-7 cells. S. hirsutum showed high resistance to methoxychlor 100 ppm, and the mycelial growth was fully completed within 8 days of incubation at 30°C. Methoxychlor in liquid culture medium was gradually converted into 2,2-dichloro-1,1-bis(4-methoxyphenyl)ethane, 2,2-dichloro-1,1-bis(4-methoxyphenyl)ethylene, 2-chloro-1,1-bis(4-methoxyphenyl) ethane, 2-chloro-1,1-bis(4-methoxyphenyl) ethylene, and 1,1-bis(4-methoxyphenyl)ethylene, indicating that methoxychlor is dominantly degraded by dechlorination and dehydrogenation. MCF-7 cells were demonstrated to proliferate actively at the 10^?5 M concentration of methoxychlor. However, cell proliferation was significantly inhibited by the incubation with methoxychlor culture media containing S. hirsutum. In addition, the expression level of pS2 mRNA was increased at the concentration (10^?5 M) of methoxychlor. The reductive effect of S. hirsutum for methoxychlor was clear but not significant as in the proliferation assay.     

白洋淀水中白腐真菌对双酚A的降解规律及途径研究

研究白洋淀表层水(白洋淀原水)、无机盐培养基、无机盐培养基强化的白洋淀原水中双酚A在白腐真菌作用下的生物降解规律,同时考察了细菌及pH等因素对降解率的影响.实验结果表明,白洋淀原水中双酚A在白腐真菌作用下的降解率很高.甚至高于最适营养条件(无机盐培养基)下双酚A的降解率.在6 d达到完全降解.但是无机盐培养基强化的白洋淀原水抑制了白腐真菌对双酚A的降解;当细菌存在时.白腐真菌与细菌对碳源和能源等形成了竞争关系,抑制了白腐真菌的生长.不利于白腐真菌对双酚A的降解;无机盐培养基强化的白洋淀原水在初始pH-6.00时双酚A的降解率高于初始pH=7.00时双酚A的降解率.通过气相色谱/质谱(GC/MS)分析.白腐真菌降解双酚A的中间产物包括2-对羟苯基-2-酮基-1-乙醇、2-羟基苯乙酸和丙二酸等小分子酸.     

Biodegradation of 4-aminobenzenesulfonate by Ralstonia sp. PBA and Hydrogenophaga sp. PBC isolated from textile wastewater treatment plant

A co-culture consisting of Hydrogenophaga sp. PBC and Ralstonia sp. PBA, isolated from textile wastewater treatment plant could tolerate up to 100 mM 4-aminobenzenesulfonate (4-ABS) and utilize it as sole carbon, nitrogen and sulfur source under aerobic condition. The biodegradation of 4-ABS resulted in the release of nitrogen and sulfur in the form of ammonium and sulfate respectively. Ninety-eight percent removal of chemical oxygen demand attributed to 20 mM of 4-ABS in cell-free supernatant could be achieved after 118 h. Effective biodegradation of 4-ABS occurred at pH ranging from 6 to 8. During batch culture with 4-ABS as sole carbon and nitrogen source, the ratio of strain PBA to PBC was dynamic and a critical concentration of strain PBA has to be reached in order to enable effective biodegradation of 4-ABS. Haldane inhibition model was used to fit the degradation rate at different initial concentrations and the parameters μ_max, K_s and K_i were determined to be 0.13 h⁻¹, 1.3 mM and 42 mM respectively. HPLC analyses revealed traced accumulation of 4-sulfocatechol and at least four unidentified metabolites during biodegradation. This is the first study to report on the characterization of 4-ABS-degrading bacterial consortium that was isolated from textile wastewater treatment plant.