茶园土壤耐酸铝酵母菌的分离鉴定及其耐铝特性的初步研究

目的为研究铝毒及耐铝机制提供更好的模式生物材料和进一步研究耐铝机制提供依据。方法通过对云南龙陵县茶园土壤耐酸铝微生物的筛选、分离和纯化,筛选出一株Y31耐酸铝酵母。结果经D1/D2区域克隆测序获取全长26S rDNA区域序列,构建系统发育树,初步鉴定Y31为长形隐球酵母（Cryptococcus longus）。在LPM培养基及GM培养基上耐铝水平检测表明Y31分别能耐100 mmol/L和50 mmol/L铝。用不同铝浓度处理酵母菌后,进行FDA PI双染色并用荧光显微镜观察,当铝浓度达到100 mmol/L时,出现明显的细胞凋亡过程。结论本研究为铝毒和生物体耐铝机制提供了生物材料。     

First Glimpse of Gut Microbiota of Quarantine Insects in China

Quarantine insects are economically important pests that frequently invade new habitats. A rapid and accurate monitoring method to trace the geographical sources of invaders is required for their prevention, detection, and eradication. Current methods based on genetics are typically time-consuming. Here, we developed a novel tracing method based on insect gut microbiota. The source location of the insect gut microbiota can be used to rapidly determine the geographical origin of the insect. We analyzed 179 gut microbiota samples from 591 individuals of 22 quarantine insect species collected from 36 regions in China. The gut microbiota of these insects primarily included Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, Proteobacteria, and Tenericutes. The diversity of the insect gut microbiota was closely associated with geographical and environmental factors. Different insect species could be distinguished based on the composition of gut microbiota at the phylum level. Populations of individual insect species from different regions could be distinguished based on the composition of gut microbiota at the phylum, class, and order levels. A method for determining the geographical origins of invasive insect species has been established; however, its practical application requires further investigations before implementation.     

Performance of Selective and Differential Media in the Primary Isolation of Yeasts from Different Biological Samples

In view of the increase in yeast infections, especially polymicrobial ones, differential culture media have acquired increasing importance. The present study evaluated the Sabouraud chloramphenicol, Biggy agar, Pagano Levin agar and CHROMagar Candida media in terms of isolation, number of yeast colony forming units per plate, and inhibition of bacteria and filamentous fungi. To this end, we used 223 biological samples, including feces, and oral, vaginal and anal mucosae from 86 patients presenting or not symptoms of fungal infections. The four media did not differ significantly in terms of detection of yeast-positive cultures. The number of colony forming units per plate ranged from zero to 2.380, with a predominance of counts of 1 to 9 colonies per plate. No significant differences were observed among the four culture media in terms of number of colonies counted, for each kind of biological material. Fifteen species belonging to the genera Candida, Saccharomyces, Cryptococcus, Trichosporon and Rhodotorula were isolated, with C. albicans being the predominant species, followed by C. parapsilosis and R. rubra. CHROMagar Candida and Biggy agar were complementary in the isolation of the different species and favored a greater recovery of polymicrobial cultures. Pagano Levin agar isolated the smallest variety of species. Sabouraud chloramphenicol agar was the least effective in terms of bacterial inhibition and favored a greater development of filamentous fungi. The results suggest that more than one culture medium should be used for an adequate primary isolation.     

Isolation and Characterization of Bacteria from the Baltic Sea

A bacteriological examination was done on samples of water and sediment from three localities in the Baltic. The highest numbers of bacteria were recovered from areas subjected to pollution. The isolates included members of the family Enterobacteria-ceae, the genus Pseudomonas and strains of Aeromonas hydrophila, Alteromonas putrefaciens and some Gram positive bacteria. It is suggested tentatively that H2S production in the black sediments was caused by Alt. putrefaciens. None of the isolates had an absolute requirement for NaCl, although all of them were salt-tolerant to varying degrees, and most were able to grow aerobically at salinities comparable with those found in seawater. Isolates belonging to the family Enterobacteriaceae were, however, unable to grow anaerobically under comparable conditions. Freshwater strains of several genera of the family Enterobacteriaceae and of Aeromonas hydrophila and Aer. sobria displayed salt tolerance identical with that of the Baltic isolates. One strain each of Escherichia coli, Klebsiella pneumoniae and Yersinia enterocolitica survived well during three weeks at 17°C in artificial seawater lacking both carbon and nitrogen sources. These results suggest the need for a re-evaluation of the persistence of potentially pathogenic bacteria in the sea.     

Isolation and Characterization of Holocellulose from Alfalfa

Holocellulose isolated from the aerial parts of alfalfa (Medicago sativa) contains a polysaccharide complex of cellulose and hemicelluloses, the major structural components of cell walls. Holocellulose is highly hydrophilic and has a dense biopolymer packing. The carboxylic groups of hemicelluloses and cellulose determines the ability of holocellulose to adsorb polyvalent metal cations.     

Isolation and Characterization of Microbodies from the Alga Chlorogonium elongatum

The alga Chlorogonium elongatum was grown autotrophically or heterotrophically on acetate. Cells harvested in the logarithmic phase of growth were disrupted, and the whole homogenates were fractionated on sucrose gradients. Protein and enzyme determinations carried out on the fractions led to the following conclusions. Chloroplast fragments which represent the major portion of particulate protein in autotrophic cells migrate to density 1.17 g/cm³. In heterotrophic cells, mitochondria comprise most of the particulate protein, and these particles accumulate at density 1.19 g/cm³, as shown by a peak of cytochrome oxidase in this region. Part of the catalase and uricase, two marker enzymes for microbodies, were found in the soluble fractions, but 60% or more of these activities were recovered at density 1.225 g/cm³ from autotrophic cells. Electron micrographs showed that in this region there were microbodies with a diameter of 0.4 micrometer. The isolated microbodies contained no isocitrate lyase, a marker enzyme of glyoxysomes. This enzyme was completely soluble and therefore seems not to be associated with organelles in this organism.     

Isolation and Characterization of Bacteria from the Swedish West Coast

Most of the bacteria isolated from water and sediment samples from a locality off the west coast of Sweden had an absolute requirement for Na+. On the basis of phenotypic characterization and determination of DNA base composition, the strains could be assigned to the genera Beneckea, Alteromonas and Pseudomonas. Apart from a group of sulphide-forming alteromonads, none of the isolates appeared to be identical with organisms described previously.     

Isolation and Characterization of Uracil-Degrading Clostridia from Soil

Five strains of uracil-degrading clostridia were isolated from soil using an enrichment medium containing uracil as the principal energy source. All the isolates resembled Clostridium glycolicum , although they lacked the characteristic ability to ferment ethylene glycol.
Both representative isolates and a reference strain of Cl. glycolicum degraded uracil and produced β-alanine when grown in a semi-defined medium. Thus, the uracil-degrading activity was similar to that described previously for Cl. uracilicum.     

石油污染土壤中植物根际促生菌的筛选及特性分析

以1-氨基环丙烷-1-羧酸(ACC)为唯一氮源,从黑龙江省大庆地区石油污染土壤的狼尾草根际土壤中分离筛选出2株产ACC脱氨酶的细菌,F4-1和F4-2。对分离的菌株进行生理生化和16S rDNA序列鉴定,确定F4-1为肠杆菌属(Enterobactersp.),F4-2为克雷伯菌属(Klebsiellasp.)。菌株F4-1的ACC脱氨酶活性为(1.40±0.17)μmolα-KA.(mg Pr.h)-1,高于F4-2的(1.03±0.03)μmolα-KA.(mg Pr.h)-1。随着L-Trp浓度的增加,菌株F4-1和F4-2的吲哚乙酸(IAA)合成量相应增加,总体上看F4-1的IAA合成能力高于F4-2。F4-1合成嗜铁素的能力也高于F4-2。     

Isolation and Characterization of Corynebacteria from Burned Children

A total of 221 strains of corynebacteria were isolated and characterized by methods which included tests encompassing five schemes proposed for grouping cutaneous diphtheroids. Seventy-one strains (group I) were isolated from the hospital air in patient areas and from the normal skins of children admitted for reconstructive surgery of old healed burns and from the normal skins of nursing personnel. One hundred and fifty strains (group II) were isolated from various clinical specimens and from normal skins of a population of acutely burned children. The majority of the strains in group I were lipophilic and contained the largest number of fluorescent strains. Among the group II strains, there was a subgroup which was nonsusceptible to oxacillin, lincomycin, erythromycin, and kanamycin and also had in common the fermentation of glucose and galactose, reduction of both nitrate and nitrite, and growth on 40% bile agar. These strains were the most commonly recognized types isolated from acutely burned patients and possibly originated from the patient's intestinal tract. Data indicated that the air was not a means of transmission for these corynebacteria among acute patients. Corynebacteria were isolated from 11% of the burn wound cultures by using a selective medium but were found in 66% of the acute patients. Over 90% of the strains in groups I and II did not conform sufficiently with described characteristics of common human indigenous corynebacteria to be accurately speciated.     

黄孢原毛平革菌基因启动子的分离与鉴定

利用启动子探针型载体pSUPV8直接在大肠杆菌(Escherichia coli)中分离黄孢原毛平革菌(Phanerochaete chrysosporium)基因启动子片段,获得6个潮霉素抗性(Hyg-r)重组子。对重组子CH2、CH6进行序列分析,结果发现它们都存在真核生物基因启动子的保守序列;用原生质体转化法将其转化黄孢原毛平革菌,仅pCH6获得了潮霉素抗性转化子;PCR和斑点杂交分析表明,pCH6已成功导入黄孢原毛平革菌,并启动潮霉素抗性基因的表达。     

Isolation and Characterization of Methanogenic Bacteria from Landfills

Methanogenic bacteria were isolated from landfill sites in the United Kingdom. Strains of Methanobacterium formicicum, Methanosarcina barkeri, several different immunotypes of Methanobacterium bryantii, and a coccoid methanogen distinct from the reference immunotypes were identified.     

异叶银合欢根瘤菌的分离和特性

从异叶银合欢K(164)和K(794)的根瘤中各分离到一株根瘤菌,并且,对K164根瘤菌的形态特征和生理生化特性进行了研究。K(164)根瘤菌在平板上培养2天,菌落呈圆形,灰白色,直径约1．2mm;革兰氏染色呈阴性,无芽孢,有美膜,两根极生鞭毛;杆菌大小为2．2×0．89μm,增代时间为1．69小时,属快生型;最适生长温度为30℃,在39℃持续2天不能存活,在20℃以下不能生长;不耐盐,较耐酸,在pH4.5～6．6范围内均能生长,但不耐碱;对庆大霉素和青霉素敏感;对供试的10种糖都能利用,不液化明胶,不利用淀粉,B．T．B试验未变色,不能进行3-酮基乳糖反应,硝酸盐反应呈阳性,石蕊牛奶试验能胨化、还原、产碱,牛肉膏蛋白胨培养生长差,能利用柠檬酸盐;在自生条件下具有吸H2酶活性;回接后结瘤率达100％,根瘤具有固氮酶和吸H2酶活性。     

番茄叶绿体DNA的分离纯化及某些性质的研究

分离纯化了番茄的叶绿体DNA(ct DNA)。热变性分析测得Tm=82.1℃,由此计算得(G+C)％=31.2％。热变性微分曲线表明,在番茄ct NDA分子上存在着碱基组成比例分布上的异质性。分析超离心测得沉降系数S_(20w)=62.4。据此计算出分子量为80×10~6d。用电子显微镜观索了制备的ctDNA.     

Isolation and Characterization of Protoplasts from Saccharomyces rouxii

Cells of the osmotolerant yeast Saccharomyces rouxii were transformed to protoplasts in good yield (85%) by digesting cell walls with snail-gut enzyme in the presence of 10 mM dithioerythritol, 0.1 M sodium phosphate buffer (pH 6.8), and 2.0 M KCl. The requirement for 2.0 M KCl compares with that for S. bisporus var. mellis (another osmotolerant species) and contrasts with the 0.3 to 0.8 M KCl concentrations used in the preparation of most yeast protoplasts. Short digestions (60 min or less) produced mostly spheroplasts; longer incubations (90 min or more) yielded mostly protoplasts as judged by electron micrographs. These protoplasts could be transferred to 1.0 M KCl or 2.0 M sorbitol without lysing, but lysis was pronounced in 0.5 M KCl or 1.0 M mannitol and complete in 0.02 M KCl. Protoplasts were separated from isolated cell wall remnants and debris by centrifugation on a linear gradient of Ficoll 400 (35 to 17.5%, wt/vol) containing 2.0 M KCl. Both crude and fractionated protoplast preparations contained vesicles which were identified with the periplasmic bodies of whole cells. Some of the periplasmic bodies were connected to protoplasts by fine pedicels; others appeared free. Independent degeneracy of periplasmic bodies was occasionally observed. beta-Fructofuranosidase (EC 3.2.1.26) activity is cryptic (physically) in cells of S. rouxii in contrast to the expressed enzyme (periplasmic space) of other Saccharomyces species. This enzyme remains cryptic in protoplast preparations of S. rouxii but is expressed upon lysis. The same specific activities were found per unit cell or protoplast. The possible association of the cryptic enzyme with periplasmic bodies is discussed.