Degradation of a Terephthalate-containing Polyester by Thermophilic Actinomycetes and <Emphasis Type="Italic">Bacillus</Emphasis> Species Derived from Composts

We intended to find thermophilic degraders of terephthalate-containing Biomax^® films. Films in mesh bags were buried in composts (inside temperature: approximately 55–60 °C), resulting in the degradation of them in 2 weeks. Fluorescent microscopy of films recovered from composts showed that microorganisms gradually covered the surface of a film during composting. DGGE analysis of microorganisms on the composted film indicated the presence of Bacillus species as main species (approximately 80% of microbial flora) and actinomycetes (approximately 10–20%) as the second major flora. Isolation of Biomax^®-utilizing bacteria was focused on these two genera: two actinomycetes and one Bacillus species were isolated as pure best degraders from the composted polymer films, which were fragmented into small pieces. All the strains were thermophilic and identified, based on their 16S rDNA analyses. Degradation of polymer films was confirmed by (1) accelerated fragmentation of films in composts, compared with a control (no inoculum) and resultant decrease in molecular weights, (2) growth in a powdered Biomax^® medium, compared with a control without powdered Biomax^®, and (3) production of terephthalate in a powdered Biomax^® medium. In this way, we concluded that these bacteria were useful for degradation of thermostable Biomax^® products.     

短小芽孢杆菌A—30耐碱性木聚糖酶基因的分子生物学研究

采用PCR方法对短小芽孢杆菌A－30菌株的耐碱性木聚糖酶基因进行克隆。在木聚糖选择平板上用刚果红染色法筛选出阳性克隆,提取阳性克隆的重组质粒进行酶切鉴定和测序。该基因在大肠杆菌中表达,过夜培养物胞外、胞内和周质空间的木聚糖酶酶活分别为0．159IUmL^-1、0.322IUmL^-1和0.007IUmL^-1。此木聚糖酶表现出较宽的pH作用范围,最适作用pH7左右,在pH9时仍有60％以上的酶活性。图4参14     

Bacillus natto TK-2产γ-絮凝活性的研究

对γ-聚谷氨酸的絮凝活性进行了研究,得出了其最佳絮凝条件为:γ-聚谷氨酸投加浓度为10mg/L;絮凝体系的pH为7.0;γ-聚谷氨酸在80℃以下都能保持很高的絮凝活性;添加不同种类的K+,Na+,Ca2+,Mg2+,Fe2+,Fe3+,Al3+能不同程度地提高γ-聚谷氨酸的絮凝活性,其中添加Ca2+的助凝效果最好,最终选择Ca2+为最佳的助凝离子并确定添加浓度为100mg/L。     

Alga-lysing bioreactor and the dominant bacteria strain

Alga-lysing bacteria have been paid much attention to in recent years. In this study, the alga-lysing strain P05 which was isolated from an immobilizing biosystem was immobilized by coke and elastic filler, forming two biological reactors. The removal efficiencies of algae, NH3-N and organic matter using the two reactors were studied. The results showed that strain P05 was an ideal algal-lysing bacteria strain because it was easy to be immobilized by coke and elastic filler which are of cheap, low biodegradability and the simple immobilization procedure. After 7 d filming, the biological film could be formed and the reactors were used to treat the eutrophic water. These two reactors were of stability and high effect with low cost and easy operation. The optimal hydraulic retention time (HRT) of each reactor was 4 h. The algae removal rates were 80.38% and 82.1% (in term of Chl-a) of coke reactor and filler reactor, respectively. And that of NH3-N were 52.3% and 52.7%. The removal rates of CODMn were 39.03% and 39.64%. The strain P05 was identified as Bacillus sp. by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database.     

Stability of green fluorescent protein using luminescence spectroscopy: is GFP applicable to field analysis of contaminants?

Green fluorescent protein (GFP) was first isolated in the early 1970s for experimental use from coelenterates or the Pacific jellyfish. Aequorea victoria (Morin and Hastings, 1971). GFP has since become a favored biomarker in the photophysical analysis of molecular and cell biology because of its strong intrinsic visible fluorescence and the feasibility of fusing it to other proteins without affecting their normal functions (Creemers et al., 2000). Here we report using Bacillus subtilis expressing GFP to evaluate the influence of different environmental pH conditions on GFP fluorescence. Emission acquisitions were configured to excite at 471 nm and detect at an emission from 490 to 650 nm at 1-nm increments. Fluorescence intensity was significantly better at pH 7 (4.2 x 105 cps; P-value < 0.01) than at acid or alkaline conditions. GFP is a good biomarker for environments near netural conditions: however, GFP may be unsuitable where soils or waters are below or above pH 7 because of loss in fluorescence intensity. Alternative fluorescent markers and delivery systems must be examined in different environments to optimize responses from bioreporter molecules.     

嗜热脂肪芽孢杆菌过氧化氢酶基因perA在大肠杆菌中的高效表达

利用PCR技术得到嗜热脂肪芽孢杆菌 (Bacillusstearothermophilus)过氧化氢酶基因 perA ,将该基因与表达载体 pKK2 2 3 3连接构建重组质粒pK perA ,转化大肠杆菌过氧化氢酶HPⅠ和HPⅡ双缺突变株UM 2 ,得到重组大肠杆菌UM 2 1.酶活测定结果表明 ,表达产物具有正常的生物学活性 .SDS PAGE电泳结果显示出明显的特异性表达条带 ,单体Mr =86× 10 3 ,与嗜热脂肪芽孢杆菌所产酶相同 .实验表明 ,重组质粒在宿主UM 2中有较好的稳定性 ,在无选择压力条件下传代 6 0次基本保持稳定 ,传代 10 0次重组质粒保留 80 %以上 .摇瓶实验确定重组菌的最佳表达条件为 :IPTG浓度 ,0 .75mmol/L ;诱导时间 3h ;培养基起始 pH 6 .5 ;诱导温度 37℃ ;装液量 5 0mL/ 2 5 0mL .在优化条件下 ,重组菌产生的过氧化氢酶占菌体总蛋白的 8% ,酶活力可达 35U/mL ,是原始菌株BacillusstearothermophilusIAM110 0 1的 11.7倍 .图 2表 1参 10     

Identification and comprehensive evaluation of a novel biocontrol agent Bacillus atrophaeus JZB120050

Abstract

Bacillus spp. have long been used as biocontrol agents because of their efficient broad-spectrum antimicrobial activity. We identified a novel strain of Bacillus atrophaeus, named JZB120050, from soil. B. atrophaeus JZB120050 had a strong inhibitory effect against Botrytis cinerea and many other phytopathogens. Gas chromatography-mass spectrometry showed that B. atrophaeus JZB120050 produced many secondary metabolites, such as alkanes, alkenes and acids; some of which were related to pathogen inhibition. Enzyme activity analysis showed that B. atrophaeus JZB120050 secreted cell-wall-degrading enzymes, including chitinase, glucanase and protease, which degraded fungal cell walls. Both the novel glucanase gene bglu and chitinase gene chit1 were cloned and heterologously expressed in Escherichia coli and the products showed strong enzyme activity. In addition, B. atrophaeus JZB120050 secreted siderophores and formed a significant biofilm. Future studies should focus on these antimicrobial factors to facilitate widespread application in the field of agricultural biocontrol.     

Bacillus thuringiensis field applications: Effect of nozzle type,drop size,and application timing on efficacy against gypsy moth

Abstract

In a series of recent studies, we evaluated the influence of delivery systems, drop size and application timing on the efficacy of aerially applied Bacillus thuringiensis against gypsy moth infestations. Use of different nozzle systems including Micronair, Flat Fan or Twin Jet, did not appear to result in significant differences in Bt coverage efficiency, foliage protection or population reduction. Nor was there any significant difference in population reduction when Bt was applied at two different drop sizes with volume median diameters of 110 and 163 μm. The efficacy of different formulations on larval populations were similar when used against the younger 1st and 2nd instar but differed when treatment was delayed until the population matured to the 3rd and 4th instar stages.     

Biodegradation of triazine herbicide metribuzin by the strain Bacillus sp. N1

By enrichment culturing of soil contaminated with metribuzin, a highly efficient metribuzin degrading bacterium, Bacillus sp. N1, was isolated. This strain grows using metribuzin at 5.0% (v/v) as the sole nitrogen source in a liquid medium. Optimal metribuzin degradation occurred at a temperature of 30ºC and at pH 7.0. With an initial concentration of 20 mg L^?1, the degradation rate was 73.5% in 120 h. If the initial concentrations were higher than 50 mg L^?1, the biodegradation rates decreased as the metribuzin concentrations increased. When the concentration was 100 mg L^?1, the degradation rate was only 45%. Degradation followed the pesticide degradation kinetic equation at initial concentrations between 5 mg L^?1 and 50 mg L^?1. When the metribuzin contaminated soil was mixed with strain N1 (with the concentration of metribuzin being 20 mg L^?1 and the inoculation rate of 10¹¹ g^?1 dry soil), the degradation rate of the metribuzin was 66.4% in 30 days, while the degradation rate of metribuzin was only 19.4% in the control soil without the strain N1. These results indicate that the strain N1 can significantly increase the degradation rate of metribuzin in contaminated soil.     

枯草芽孢杆菌对土臭素和2-甲基异冰片的降解动力学特性

土臭素(geosmin,GSM)和2-甲基异冰片(2-methylisoborneol,2-MIB)是2种普遍存在于养殖水体中的土腥异味化合物,微生物降解是去除这两种物质的有效途径.本文研究了枯草芽孢杆菌(Bacillus subtilis)降解GSM和2-MIB的动力学特性.结果表明,枯草芽孢杆菌对GSM(1 000~2 000 ng·L-1)和2-MIB(1 000~2 000 ng·L-1)具有较好的降解性能,降解率均达90%以上;枯草芽孢杆菌对这些异味化合物的降解符合伪一级反应动力学,其生物降解速率常数(K)范围为0.14~0.41,降解速率不随GSM和MIB初始浓度的变化而变化;枯草芽孢杆菌对GSM降解的最大比生长速率umax为0.311,Monod常数KS为1.73,而在降解MIB过程中枯草芽孢杆菌的生长不符合Monod方程(R2=0.781).