Isolation and characterization of an obligate methanol-utilizing bacteriumMethylomonas M-15

Summary A new obligate methylotrophic bacterium capable of rapid growth on methanol as its sole carbon and energy source was isolated. The organism grows only on methanol and not on methane or methylamine. It is a gram-negative, motile rod (0.5×1.5 m) with a single polar flagellum and was therefore classified as a species ofMethylomonas.The doubling time was about 2 hr at pH 7.0, at a temperature of 30 to 36°C and at a methanol concentration of 1% (v/v).Cell suspensions were able to oxidize methanol, formaldehyde, and formate; therefore it seems that methanol-, formaldehyde-, and formate-oxidizing enzymes are present in the bacterium. While no hydroxy pyruvate reductase activity was found, the cell extract contained high hexulose phosphate-synthetase activity, indicating the assimilation of methanol via the ribulose phosphate-pathway.The protein content of the bacterium is 60% and the amino acid pattern indicates that this strain could serve as a good source of single cell protein.     

一株甲醇利用菌的分离及其在甲醇测定中的应用

【目的】筛选能够利用甲醇的微生物菌株,并将其应用于甲醇测定的初步研究中。【方法】采用富集培养及固体平板分离法分离菌株;通过生理生化特征及16S rDNA序列分析进行菌株鉴定;以固定化细胞和溶氧仪组合成测定系统,测定了不同含量甲醇的响应时间以及溶氧变化与甲醇含量的关系。【结果】从山西清徐农用沼气池中分离得到一株能以甲醇为唯一碳源和能源生长的菌株M211,通过生理生化特征及16SrDNA序列分析,该菌株被鉴定为嗜有机甲基杆菌(Methylobacterium organophilium)。传感系统在0.02%-1%(V/V)甲醇含量范围内测定,响应时间小于20 min,检出限为0.27 mg/L,溶氧消耗量同甲醇含量呈线性关系,拟合系数(R2)为0.9986。该测定体系不易受其它干扰物质影响,检测结果与实际样品浓度一致。【结论】该测定体系具有较强的选择性,及良好的重现性和稳定性,具有较好的应用前景。     

一株纤维素分解菌的分离与筛选

以新华滤纸为唯一碳源,从垃圾堆肥中筛选能够分解纤维素的菌株共39株,采用刚果红鉴别培养基进行识别,获取透明圈较大的菌株10株,在此基础上,进行液体培养,测定酶活,得到1株酶活较高的曲霉B－6（Aspergillus sp)。将B－6与绿色木霉（Trichoderma sp)AS3.3711进行了参比试验,比对筛选工作进行评定,经过固体,液体发酵对比试验,发现B－6与AS3．371有相近的产酶性能,B－6在固,液发酵中酶活分别达到39．2IU,14．9IU,而S3．3711则分别为16．6IU与15．7IU,且B－6较AS3．3711有更强的液化CMC的能力,B－6在24h内即能使3％CMC完全液化,而S3．3711则需96h。     

生物表面活性剂产生菌的筛选及表面活性剂稳定性研究

大庆油田油泥样品经富集培养,平板分离,获得52株菌。排油性实验和表面张力测定表明,菌株B22、B24、B2s产生的表面活性剂表面活性稳定,表面张力较低。温度、pH和NaCl浓度实验证实,细菌B22,产生的生物表面活性剂可耐受120℃高温,另2种生物表面活性剂可耐受80℃;3种细菌生物表面活性剂对pH有广泛适应性,1322pH适应范围为4．0～13．0,B24、B25的pH适应范围为2．0～13．0;NaCl浓度对表面活性剂的生物活性影响不大。将3株菌的生物表面活性剂用于室内油泥处理实验,72h石油去除率达70％以上。     

全氟辛烷磺酸降解菌的分离与鉴定

目的筛选和分离降解全氟辛烷磺酸(PFOS)的细菌,并进行初步鉴定和降解效率分析。方法采集全氟化工厂周边土壤,利用PFOS为唯一碳源的无机盐培养基进行驯化和富集培养,分离降解PFOS的细菌;通过形态观察、生理生化特性检测和基于16SrRNA基因序列的系统发育分析对分离菌株进行鉴定;采用GC-MS检测其降解PFOS的能力。结果分离获得3株能降解PFOS的细菌YSB1、YSB2和YSB3,初步鉴定分属于鞘酯菌属(Sphingobiumsp.)、中华根瘤菌属(Sinorhizobiumsp.)和苍白杆菌属(Ochrobactrumsp.)。菌株YSB1、YSB2和YSB3在以PFOS为唯一碳源生长的无机盐培养基中生长良好,其对PFOS最大降解率分别为18.4%、10.1%和14.1%。结论自然界存在较丰富的降解持久性有机污染物PFOS的微生物资源。     

Isolation and characterization of acid- and Al-tolerant microorganisms

Acid- and aluminum (Al)-tolerant microorganisms were isolated from tea fields, from which six strains were selected and identified as Cryptococcus humicola, Rhodotorula glutinis, Aspergillus flavus Link, Penicillium sp., Penicillium janthinellum Biourge and Trichoderma asperellum. They were tolerant to Al up to 100-200 mM and could grow at low pH, 2.5-2.2. In a glucose medium (pH 3.5) the pH of the spent medium decreased to below 3.0. The toxic inorganic monomeric Al in the spent medium decreased with three strains (A. flavus F-6b, Penicillium sp. F-8b and P. janthinellum F-13), but the total Al remained constant for all strains. In a soil extract medium (pH 3.5), the pH of the spent medium of all strains increased to around 6.0-7. 2 and total Al in the spent medium was removed by precipitation due to pH increase. Thus, different tolerance mechanisms were suggested in glucose and soil extract media.     

Systematics of methanol-utilizing bacteria

Abstract Aerobic, Gram-negative methanol-utilizing bacteria that do not utilize methane are divided into 11 taxa. Two taxa are obligatedor restricted facultative methanol utilizers and nine taxa are facultative methanol utilizers. The phylogenetic relationship within the methanol utilizers is discussed on the basis of 16 S and 5 S ribosomal RNA sequences.     

Isolation of polyacrylamide-degrading microorganisms from soil

Two polyacrylamide-degrading bacterial strains, No. 2 and No. 11, were isolated from soil, and identified asBacillus sphaericus No. 2 andAcinetobacter sp. No. 11, respectively. Both strains grew on medium containing polyacrylamide as sole carbon and nitrogen sources.B. sphaericus No. 2 andA. sp. No. 11 reduced by 16% and 19% of the initial polyacrylamide concentration, respectively. Optimal pH and temperature in growth ofAcinetobacter sp. No. 11 were 8.0 and 37°C, respectively. After 14-day cultivation ofA. sp. No. 11, the average molecular weight of polyacrylamide has been shifted from 2.3×10⁶ to 0.5×10⁶.     

Isolation,taxonomy and phylogeny of hyperthermophilic microorganisms

Hyperthermophilic Archaea and Bacteria with optimal growth temperatures between 80 and 110°C have been isolated from geo- and hydro-thermally heated terrestrial and submarine environments. 16S rRNA sequence comparisons indicate great phylogenetic diversity among the 23 different genera represented. Hyperthermophiles consist of anaerobic and aerobic chemolithoautotrophs and heterotrophs growing at neutral or acidic pH. Their outstanding heat resistance makes them as interesting objects for basic research as for biotechnology in the future.The authors (alphabetical order) are with the Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, 93053 Regensburg, Germany     

Isolation, propagation and characterisation of Cryptosporidium

This review consists of 11 papers presented at the Consensus Conference on Cryptosporidium in Water (Parasitology Stream), held in Melbourne, Australia, from 5 to 6th October 1998. The conference was sponsored by the Water Services Association of Australia, the Australian Water and Wastewater Association, and the Collaborative Research Centre for Water Quality and Treatment. The papers summarise the advantages and disadvantages of various contemporary technologies applicable to parasite propagation and biochemical/molecular characterisation. Studies have detected distinct genetic differences between clinical isolates from humans and animals, and it is hoped that comprehensive documentation studies will facilitate the identification of environmental isolates in the not too distant future.     

Electron microscopy of methanol-utilizing bacteria

Two different groups of methanol-utilizing bacteria were studied by electron microscopy. Bacteria using the serine pathway for the assimilation of methanol were found to have a thin cell envelope (outer membrane, periplasmic area and cytoplasmic membrane). Those using the assimilatory ribulose monophosphate pathway of formaldehyde fixation had a much thicker cell envelope and in the case ofPseudomonas C protrusions of the outer membrane were found.     

Growth of a methanol-utilizing yeast

A halophilic thermotolerant yeast species, identified as Hansenula polymorpha Morais et Maia, was isolated from a mixed culture obtained from sea-water from the Arabian Gulf. The species grew on methanol at 25–42°C, pH 3.5–6.7, and in a medium compounded with 75% sea-water. Either thiamin HCl and biotin or yeast extract proved essential for growth. In shake flask studies a depression of the yield was observed when methanol concentration increased; at concentrations in excess of 0.1%, v/v, inhibition of growth also occurred. In a batch culture grown in a 14 l fermenter, the values of T_d, μ and Y_s were found to be 3 h, 0.23 h⁻¹ and 0.38, respectively.     

Isolation and screening of microorganisms dissolving low-grade rock phosphate

Several yeasts, fungi and bacteria isolated from the rhizosphere of leguminous crops and soils of rock phosphate deposit area were found to solubilize low-grade Mussorie rock phosphate. Of the several yeasts and fungi,Schawanniomyces occidentalis, Aspergillus awamori andPenicillium digitatum were better than others in rock phosphate solubilization. Among bacterial isolates from soils of rock phosphate deposits, Gram-negative motile rods were more effective than Gram-negative non-motile rods in dissolving rock phoshates. The most efficient bacteria were identified as strains ofPseudomonas striata. All the microorganisms acidified the liquid medium but there was no relationship between the rock phosphate dissolved and the decrease in pH of the culture broth.     

糕点、面包中污染细菌的分离及菌种的初步鉴定

以市场中不同厂家保质期内的9种糕点、面包类食品为实验对象,对其污染细菌进行了初步分离鉴定。结果表明:冷加工样品的细菌总数均超标,从污染细菌中分离检出的细菌主要是葡萄球菌属和明串珠菌属的菌株。这意味着冷加工产品受污染主要是由环境不符卫生标准,其次是操作人员的不卫生操作及添加原辅料被污染所引起。