Microbial biodegradation of microcystin-RR by bacterium Sphingopyxis sp. USTB-05

A strain,USTB-05,isolated from Lake Dianchi,China,degraded the cyanobacterial toxin microcystin-RR(MC-RR) at the rate of 16.7 mg/L per day.Analysis of 16S rDNA sequence showed that the strain was Sphingopyxis sp.Enzymatic degradation pathways for MC-RR by Sphingopyxis sp.USTB-05 were identified.Adda-Arg peptide bond of MC-RR was cleaved and then a hydrogen and a hydroxyl were combined onto the NH 2 group of Adda and the carboxyl group of arginine to form a linear molecule as intermediate product within the ...     

Decolorization of molasses melanoidins and palm oil mill effluent phenolic compounds by fermentative lactic acid bacteria

Lactobacillus plantarum SF5.6 is one of the lactic acid bacteria (LAB) that has the highest ability of molasses melanoidin (MM) decolorization among the 2114 strains of LAB. The strains were isolated from spoilage, pickle fruit and vegetable, soil and sludge from the wastewater treatment system by using technical step of enrichment, primary screening and secondary screening. This LAB strain SF5.6 was identified by 16S rDNA analysis and carbohydrate fermentation (API 50 CH). The top five LAB strains having high MM decolorization ( 55%), namely TBSF5.8-1, TBSF2.1-1, TBSF2.1, FF4A and SF5.6 were selected to determine the optimal condition. It was found that the temperature at 30°C under facultative conditions in GPY-MM medium (0.5% glucose, 0.1% peptone, 0.1% yeast extract, 0.1% sodium acetate, 0.05% MgSO4 and 0.005% MnCl2 in MM solution at pH 6) giving a high microbial growth and MM decolorization for all five strains. It was noticed that the decolorization of MM by LAB strains might be cell growth associated. L. plantarum SF5.6 grew rapidly within one day while the other strains took 2–3 days. This L. plantarum SF5.6 could rapidly decolorize MM to 60.91% without any lag phase, and it also had the ability to remove 34.00% phenolic compounds and 15.88% color from treated palm oil mill effluent.     

Decolorization of molasses melanoidins and palm oil mill e uent phenolic compounds by fermentative lactic acid bacteria

Lactobacillus plantarum SF5.6 is one of the lactic acid bacteria (LAB) that has the highest ability of molasses melanoidin (MM) decolorization among the 2114 strains of LAB. The strains were isolated from spoilage, pickle fruit and vegetable, soil and sludge from the wastewater treatment system by using technical step of enrichment, primary screening and secondary screening. This LAB strain SF5.6 was identified by 16S rDNA analysis and carbohydrate fermentation (API 50 CH). The top five LAB strains having high MM decolorization (> 55%), namely TBSF5.8-1, TBSF2.1-1, TBSF2.1, FF4A and SF5.6 were selected to determine the optimal condition. It was found that the temperature at 30°C under facultative conditions in GPY-MM medium (0.5% glucose, 0.1% peptone, 0.1% yeast extract, 0.1% sodium acetate, 0.05% MgSO4 and 0.005% MnCl2 in MM solution at pH 6) giving a high microbial growth and MM decolorization for all five strains. It was noticed that the decolorization of MM by LAB strains might be cell growth associated. L. plantarum SF5.6 grew rapidly within one day while the other strains took 2–3 days. This L. plantarum SF5.6 could rapidly decolorize MM to 60.91% without any lag phase, and it also had the ability to remove 34.00% phenolic compounds and 15.88% color from treated palm oil mill e uent.     

4株邻苯二甲酸二丁酯降解菌的分离鉴定及其相关降解基因的克隆

从土壤中分离纯化出4株能降解邻苯二甲酸二丁酯(DBP)的菌株,分别命名为JDC-1、JDC-8、JDC-9、JDC-12,并对其进行了形态学、生理生化及分子生物学鉴定.菌株革兰氏染色阳性,16S rDNA序列分析显示4株菌均与节杆菌属(Arthrobacter sp.)有99%以上的序列相似性,初步判断这4株菌为Arthrobacter sp..通过PCR扩增及克隆,均获得了1个约900 bp的DNA片段,测序结果显示该片段与Arthrobacter keyseri的邻苯二甲酸3,4-双加氧酶基因的核苷酸序列相似性为96%以上.对4株菌的最适生长条件及对DBP的降解能力进行了分析,结果显示,4株菌的最适生长条件为pH 7.0~8.5,温度30~35℃.以DBP作为目标测试物,在适宜条件下测试了4株菌的降解能力,显示这4株菌均为高效降解菌,效率最高的JDC-1能在28 h内将500 mg/L的DBP降解完全,最慢的JDC-8经40 h能将500 mg/L的DBP降解完全,本研究对于DBP降解机制的研究及微生物资源的开发都具有重要意义.     

“Achromobacter sp. CH-1-Cr(Ⅵ)-H2O”体系Cr(Ⅵ)还原的电化学行为

采用循环伏安法探明了"Achromobacter sp.CH-1-Cr(Ⅵ)-水"体系的电化学行为.结果表明:循环伏安曲线上-0.62V(相对于SCE)的电流峰对应的反应为Cr(Ⅵ)还原成Cr(Ⅲ)的反应,在电势为-0.82V时Cr(Ⅲ)开始还原为零价铬.体系中的电极反应为不可逆过程,阳极扫描时Cr(Ⅲ)不会被重新氧化为Cr(Ⅵ).细菌的存在使Cr(Ⅵ)的还原更容易进行,其还原峰电势正移约0.2 V,细菌对体系中的电化学反应起了催化作用.随细菌量的增加,氢气的析出、六价铬还原为三价铬及三价铬进一步还原为零价铬的电势均发生了正移,过高的细菌量主要影响三价铬还原沉积为金属铬的过程.铬浓度对细菌还原Cr(Ⅵ)溶液的循环伏安曲线的影响不大.初始pH值为10是细菌还原Cr(Ⅵ)的最佳pH值.     

Enterobacter sp.CV-v对孔雀石绿的脱色特性及机理研究

采用单因素实验研究了各种操作因素对菌株Enterobacter sp.CV-v降解孔雀石绿的影响.结果表明,在供试碳源中,葡萄糖对脱色的促进效果最为显著,而供试氮源中,酵母粉对脱色的促进效果最优;同时,供试金属离子中,锰离子对脱色的促进效果最优.在p H=3.0~10.0、温度20~50℃之间时,菌株CV-v对孔雀石绿的12 h脱色率在90%以上.此外,该菌株可在6 h内完全脱色浓度低于500 mg·L-1的孔雀石绿.动力学实验结果表明,该菌株对孔雀石绿脱色的动力学数据与一级动力学模型拟合度最好(R2=0.9755).酶分析实验结果表明,锰过氧化物酶和孔雀石绿还原酶可能与菌株CV-v降解孔雀石绿相关.此外,代谢产物分析实验结果表明,菌株CV-v降解孔雀石绿的主要产物为二甲氨基二苯甲酮和4-羟基-N,N-二甲基苯铵.     

细菌降解非离子表面活性剂的研究

从石油污染的土壤中分离到２株能利用非离子表面活性剂ＡＥＯ－９和ＳＡ－２０作为唯一碳源生长的细菌。这２株菌被定名为假单胞杆菌５２（Ｐｓｅｕｄｏｍｏｎｏｓ５２）和Ｗｅｅｋｓｅｌｌａ６．最适于这２株菌利用非离子表活剂ＡＥＯ－９的培养条件是乙酸胺作为氮源,ｐＨ７．３０℃添加少量葡萄糖促进表活性的降解,降解速率的研究表明,当ＡＥＯ－９的初始浓度为５０００ｍｇ／Ｌ时,５２号菌和６号菌能在２周内将其去除８５％,     

沤肥浸渍液对3种黄瓜病害的防治作用

从１９９２ 年开始连续８ 年研究马、牛和猪厩肥沤制并浸泡提取物对黄瓜病害的防治作用．盆栽试验表明,沤肥浸渍液对黄瓜霜霉病、黄瓜枯萎病、黄瓜白粉病具有良好的防治效果,对黄瓜霜霉病的防治效果可达４６ ．５ ％６７ ．３ ％ ,对黄瓜枯萎病的防治效果可达７２ ．１ ％９２ ．５ ％ ,对黄瓜白粉病的防治效果可达７２ ．３ ％７９ ．７ ％ ．对沤肥浸渍液的防病机理的研究表明,微生物代谢产物对病原菌孢子的抑制作用、沤肥中微生物对病原菌的拮抗作用和沤肥诱导的生理生化和组织形态方面的抗病性起着重要的作用     

慢生型花生根瘤菌16S rRNA分析

以２１株分离自四川,云南不同花生产区的慢性型花生根瘤菌和６株参比菌株为材料,进行了１６ＳｒＤＮＡＰＣＲ－ＲＦＬＰ,结果除证实了慢性型花生根瘤菌同慢生型大豆根瘤菌（Ｂｒａｄｙｒｈｉｚｏｂｉｕｍｊａｐｏｎｉｃｕｍ）高度的遗传相似性外,还发现了一些菌株同Ｂｒａｄｙｒｈｉｚｏｉｂｉｕｍｌｉａｏｎｉｎｇｅｎｓｉｓ和Ｂｒａｄｙｒｈｉｚｏｂｉｕｍｅｌｋａｎｉｉ有较高的遗传相似性,菌株Ｓｐｒ１－２的１６ＳｒＲＮＡ     

红球菌Chr-9降解吡啶和苯酚的特性

研究了红球菌(Rhodococcus)Chr-9菌株在基础盐培养基中降解吡啶和苯酚的特性,分析了菌株降解苯酚和吡啶间的差异.结果表明,菌株Chr-9能够在72 h内将基础盐培养基中的吡啶(200 mg L-1)和苯酚(200 mg L-1)完全降解,同时利用吡啶和苯酚进行生长.菌株降解吡啶的最适温度为35℃,最适pH为8.0.菌株降解吡啶和苯酚的速度与底物的初始浓度呈负相关;在无其它氮源的基础盐培养基中,菌株能够利用吡啶和苯酚协同生长.图7参12