Biodegradation of pendimethalin by Bacillus subtilis Y3

A bacterium strain Y3,capable of efficiently degrading pendimethalin,was isolated from activated sludge and identified as Bacillus subtilis according to its phenotypic features and 16 S rRNA phylogenetic analysis.This strain could grow on pendimethalin as a sole carbon source and degrade 99.5%of 100 mg/L pendimethalin within 2.5 days in batch liquid culture,demonstrating a greater efficiency than any other reported strains.Three metabolic products,6-aminopendimethalin,5-amino-2-methyl-3-nitroso-4-(pentan-3-ylamino) benzoic acid,and 8-amino-2-ethyl-5-(hydroxymethyl)-1,2-dihydroquinoxaline-6-carboxylic acid,were identified by HPLC-MS/MS,and a new microbial degradation pathway was proposed.A nitroreductase catalyzing nitroreduction of pendimethalin to 6-aminopendimethalin was detected in the cell lysate of strain Y3.The cofactor was nicotinamide adenine dinucleotide phosphate(NADPH) or more preferably nicotinamide adenine dinucleotide(NADH).The optimal temperature and pH for the nitroreductase were 30℃ and 7.5,respectively.Hg~(2+),Ni~(2+),Pb~(2+),Co~(2+),Mn~(2+) Cu~(2+),Ag~+,and EDTA severely inhibited the nitroreductase activity,whereas Fe~(2+),Mg~(2+),and Ca~(2+) enhanced it.This study provides an efficient pendimethalin-degrading microorganism and broadens the knowledge of the microbial degradation pathway of pendimethalin.     

锰过氧化物酶的固态发酵及其对染料的脱色作用

采用稻壳作为基质,利用裂褶菌F17固态发酵产锰过氧化物酶(MnP),通过正交实验对发酵条件进行优化,并对5种不同结构类型的染料进行脱色.结果显示,含水率、温度、Mn2 、Cu2 对裂褶菌F17产MnP有显著影响;MnP发酵的最优化条件为稻壳27g、黄豆粉3g、MnSO40.4mg·g-1、含水率150%、接种量50%、培养温度22℃,pH不调节,优化后酶活达到16.39 U·g-1,比优化前的酶活9.20 U·g-1提高了78.2%.优化后的发酵体系对染料刚果红、茜素红、Poly R-478、中性红和结晶紫的24h脱色率分别达到92.6%、90.3%、93.1%、87.3%和95.6%.     

Biosorption of Cu(Ⅱ) on extracellular polymers from Bacillus sp.F19

Biosorption can be an effective process for the removal of heavy metals from aqueous solutions.The adsorption of Cu(Ⅱ) from aqueous solution on the extracellular polymers (EPS) from Bacillus sp.(named MBFF19) with respect to pH,incubation time,concentration of initial Cu(Ⅱ),and biosorbent dose was studied.Biosorption of Cu(Ⅱ) is highly pH dependent.The maximum uptake of Cu(Ⅱ) (89.62 mg/g) was obtained at pH 4.8.Biosorption equilibrium was established in approximately 10 min.The correlation coeffcient of mor...     

红球菌PR-1菌株破乳性能研究

利用乳化剂Span 80配制出一种稳定的煤油-水乳浊液作为模型乳浊液,进而从大港油田废水中筛选出1株破乳能力较强的红球菌PR-1.该菌株培养液在55℃下8h可以使模型乳浊液完全破乳,且在实验条件下比化学破乳剂DGF-01具有更强的破乳活性.研究发现,乳浊液的破乳为线性增长过程,冻融和高压灭菌对其破乳能力没有影响,菌体细胞是破乳的主要活性成分,经超声波破碎及有机溶剂处理后其破乳活性显著降低.菌体表面有很强的疏水性,其对烃的粘附率为84%,碳链长度范围在C₂₇～C₅₄的枝菌酸类物质是保持菌体细胞完整性和疏水性的关键,其对细胞的破乳活性也至关重要.PR-1菌株发酵液用于原油乳状液的破乳具有操作方便,破乳率高,应用面广,无毒无害等优点,且能完全脱出J9-19原油乳状液中的水,因此可作为原油乳状液或油田采出水的破乳剂.     

多效唑的生物降解性研究

利用从多效唑生产废水排放口土壤中富集获得的混合微生物和纯培养菌研究多效唑的生物降解性。结果表明，微生物生物量与多效唑相对浓度之间呈高度负相关（ｒ＝－０９３）。混合微生物降解多效唑较纯培养菌株快，降解的最适温度为３０℃，最适ｐＨ值为７０，对高ｐＨ值有耐受性。好氧和厌氧条件下微生物均能降解多效唑。富集培养物中的主要构成菌为假单孢菌属（Ｐｓｅｕｄｏｍｏｎａｓｓｐ）。降解动力学反应遵循Ｍｏｎｏｄ关系式。     

应用黑褐新糠虾测试织纹螺毒性的初步研究

尝试以黑褐新糠虾作为实验生物,研究了投喂不同毒性的织纹螺对糠虾存活的影响,并探讨了这一方法在织纹螺毒性测试中的应用.实验结果表明:有毒织纹螺能够导致黑褐新糠虾中毒死亡,糠虾的半致死时间与织纹螺的毒性之间有显著的相关性(R2=0.9943),在96 h内织纹螺对糠虾的半致死毒性为40.11 MU/g.利用黑褐新糠虾作为实验生物可以测试织纹螺样品毒性的高低,方法的检出限约为10.44 MU/g,与日本法定的河豚鱼食用安全标准(10 MU/g)相当.