基于16S rRNA 基因的戈登氏菌演化分析

探讨19种戈登氏菌共31株间16S rRNA基因演化关系。利用16S rRNA基因序列进行相似性分析和同源性比对,并运用Neighbor-Joining法构建进化树,进行演化分析。其中13条16S rRNA基因序列来自临床分离株,其他16S rRNA基因序列来自Genbank。结果表明：13株临床分离菌株包含4株Gordonia paraffinivorans,6株Gordonia bronchialis 和3株 Gordonia sputi,临床分离株的相似性百分比为93．5％-99．7％;16S rRNA基因序列在戈登氏菌不同种间存在较为明显的差异性（2％—6．2％）,可将临床分离株鉴定到种。进化分析结果显示：戈登氏菌分为两大类群,三种临床分离株在演化上按出现的先后依次为Gordonia bronchialis、Gor-donia sputi、Gordonia paraffinivorans。所做研究可为戈登氏菌相关疾病的流行、预防、治疗和控制提供一定的参考。     

优良醋酸菌种AC2005的鉴定

将醋酸杆菌AC2005 16S rDNA片段转入载体pMD18-T,并转化大肠埃希氏杆菌(Escherichia coli).经测序和序列分析显示,醋酸杆菌AC2005 16S rDNA片段与巴斯德醋杆菌16S rDNA片段同源性均达95%.根据醋酸杆菌AC2005 16S rDNA的生理生化特征培养特征,形态特征结果将醋酸杆菌AC2005归属为巴斯德醋酸杆菌罗旺亚种(Acetobactor.pasteurianus subsp.lovaniensis).     

Isolation and identification of Rhodosporidium diobovatum DS-0205 from deep-sea sediment of eastern Pacific Ocean

A facultative heterotrophic strain (DS-0205) was isolated from a deep-sea sediment sample collected at a depth of 5.2 km in the eastern Pacific Ocean, China. Strain DS-0205 is motile helmet-like single cell or pairs, forming hemisphere with the center sunken of variable size. It has a widespread carbon source and nitrogen source, including agarose, citric acid, salicin, D-glucitol nitrate, sodium nitrite and ethylamine. It can grow in the following environment: temperature 4–37 °C, pH 2.0–12.0, tolerance to NaCl⩽15%. Two phylogenetic trees, one based on the ITS and 5.8S rRNA sequences and the other based on the 18S rRNA sequences, unite strain DS-0205(=JCM 0205) to the type strain of Rhodosporidium diobovatum JCM 3787 through a considerable evolutionary distance. These results suggest that strain DS-0205 is a new strain of the Rhodosporidium diobovatum.     

青岛和大连海区海带(Laminaria japonica)外生细菌的16S rRNA基因序列分析

从采集自青岛和大连的大型褐藻海带(Laminaria japonica)表面分离到22株革兰氏阴性海洋细菌。根据16SrRNA基因序列分析结果,将其分别鉴定为假交替单胞菌(Pseudoalteromonas,Cobetia)菌,嗜冷单胞菌(Psychromonas),交替单胞菌(Alteromonas),产碱杆菌(Alcaligens)和海杆菌(Marinobacter)。其中假交替单胞菌在两地样品中占据绝对优势,但每个产地的假交替单胞菌不能单独聚类在一起,不同海区的海带表面存在遗传关系非常接近的菌株。假交替单胞菌之外的其他菌株于两地样品之间存在种或属水平上的差异。本文结果提示外生细菌的种类既与环境相关,又受宿主的状况影响。对8株受试菌株的拮抗实验结果显示了外生细菌在寻找新型抗生素方面的潜力。     

Optimization of substrates for Bioelectricity production by Ochrobactrum pseudintermedium KF026284 in a single chambered microbial fuel cell

A new strain of bacterium Ochrobactrum pseudintermedium KF026284 was isolated from a single chambered microbial fuel cell operated with rumen fluid. The bacterium produced maximum power density of 114 mW/m² (0.7 V, 0.6 mA) when nutrient broth was used as the growth medium. The optimization of electricity generation by O. pseudintermedium KF026284 was carried out using various substrates like cellulose, cellobiose, starch, sucrose, and glucose. The bacterium when fed with cellobiose showed an appreciable and sustainable electricity generation with a power density of 150 mW/m² from the 5th day and a maximum power density of 247 mW/m² on the 11th day.     

A study of external mass transfer effect on biodegradation of phenol using low‐density polyethylene immobilized Bacillus flexus GS1 IIT (BHU) in a packed bed bioreactor

The impact of external mass transport on the biodegradation rate of phenol in a packed bed bioreactor (PBBR) was studied. A potential bacterial species, Bacillus flexus GS1 IIT (BHU), was isolated from the petroleum‐contaminated soil. Low‐density polyethylene (LDPE) immobilized with the B. flexus GS1 IIT (BHU) was used as packing material in the PBBR. The PBBR was operated by varying the inlet feed flow rate from 4 to 10 mL/min, and the corresponding degradation rate coefficients were found to be in the range of 0.119–0.157 L/g h. In addition, the highest removal rate of phenol was obtained to be 1.305 mg/g h at an inlet feed rate of 10 mL/min. The external mass transfer was studied using the model . A new empirical correlation for the biodegradation of phenol in the PBBR was developed after the evaluation at various values of K and n.     

A multiplex-conventional PCR assay for bovine,ovine, caprine and fish species identification in feedstuffs: Highly sensitive and specific

A multiplex PCR assay was developed for rapid and reliable identification of bovine, ovine, caprine and fish species in feedstuffs simultaneously. The method merges the use of bovine, ovine, caprine and fish primers that amplify fragments (ovine; 119 bp, caprine; 142 bp, fish; 224 bp and bovine; 271 bp) of the mitochondrial t.glu gene forward and cyt b reverse, 12S rRNA, 12S rRNA, and ATPase subunit 8 genes respectively, and a universal 18S rRNA primers that amplifies a 99 bp from eukaryotic DNA. To evaluate the effect of heat treatment, a severe sterilization condition (133 °C at 300 kPa for 20 min) was applied. Multiplex analysis of the reference feedstuff samples showed that the detection limit of the assay was 0.01% for each species. Taken together, all data indicated that this multiplex PCR assay was a simple, rapid, sensitive, specific, and cost-effective detection method for bovine, ovine, caprine and fish species in feedstuffs.     

A highly efficient method for concentrating DNA from river water by combined coagulation and foam separation

ABSTRACT

Both Escherichia coli and Enterococci were collected in foam within 7 min from 500 mL of bacteria-spiked water by coagulation and foam separation using ferric chloride and milk casein. These bacterial DNA isolated in the 100 µL of extract from the foam more than 87.5% recovery using the DNeasy PowerWater® Kit. To test this method with water from three natural rivers, 0.67–2.70 µg of DNA were concentrated in 100 µL of extract from 1,000 mL of river water. When the DNA extract was subjected to 16S rRNA gene sequencing analysis, information on the bacterial flora could be obtained.     

Cultivable bacterial diversity and amylase production in three typical Daqus of Chinese spirits

Both culture‐dependent method and molecular technique were firstly used to simultaneously investigate the cultivable bacterial diversity and amylase production in three typical Daqus of Chinese spirits. The results showed that both cultivable bacterial diversity and amylase production were obviously different. The species of nine bacteria from Deshan, nine from Baisha and six from Wuling Daqus were identified. The total bacterial strains of 17, 15 and 14, and 9, 16 and 10 could produce α‐amylase and glucoamylase, respectively, from the Daqus, and the enzyme yields were different. Bacillus licheniformis, Bacillus subtilis and Bacillus amyloliquefaciens not only were dominant bacteria in the Daqus, but also possessed high activities of α‐amylase and glucoamylase. By comparison, Bacillus cereus and Bacillus oleronius were found to be another predominant bacterial species and good producers of α‐amylase and glucoamylase in Deshan and Wuling Daqus, respectively.     

Electricity generation and microbial community structure of air-cathode microbial fuel cells powered with the organic fraction of municipal solid waste and inoculated with different seeds

The organic fraction of municipal solid waste (OFMSW), normally exceeding 60% of the waste stream in developing countries, could constitute a valuable source of feed for microbial fuel cells (MFCs). This study tested the start-up of two sets of OFMSW-fed air-cathode MFCs inoculated with wastewater sludge or cattle manure. The maximum power density obtained was 123 ± 41 mW m⁻² in the manure-seeded MFCs and 116 ± 29 mW m⁻² in the wastewater-seeded MFCs. Coulombic efficiencies ranged between 24 ± 5% (manure-seeded MFCs) and 23 ± 2% (wastewater-seeded MFCs). Chemical oxygen demand removal was >86% in all the MFCs and carbohydrate removal >98%. Microbial community analysis using 16S rRNA gene pyrosequencing demonstrated the dominance of the phylum Firmicutes (67%) on the anode suggesting the possible role of members of this phylum in electricity generation. Principal coordinate analysis showed that the microbial community structure in replicate MFCs converged regardless of the inoculum source. This study demonstrates efficient electricity production coupled with organic treatment in OFMSW-fueled MFCs inoculated with manure or wastewater.