Some Properties of Pentachloro-phenol-resistant Gram-negative Bacteria

The effects of derivatives containing Lys–Asp sequences on growth-hormone-mediated lipolysis were examined for fat cells isolated from rat epididymal adipose tissue. A dipeptide, Lys–Asp, had a weak but distinct ability to induce lipolysis and inhibit growth-hormone-mediated lipolysis. Among the derivatives tested, Lys(Z)–Asp(OEt)–QEt (6d), Lys(Z)–Asp(OC₄H₉)–OC₄H₉ (6e), Lys(Z)–Asp(OC₈H₁₇)–OC₈H₁₇ (6f), C₇H₁₅CO–Lys(Z)–Asp (4b), and C15H₃₁CO-Lys(Z)Asp (4c) had a fairly high lipolytic activity. The derivatives 6e, 6d and 4c inhibited growth-hormone-mediated lipolysis. A derivative, C₁₅H₃₁CO–Lys–Asp(OMe)–QMe (3c), had no lipolytic activity but strongly inhibited for growth-hormone-mediated lipolysis. It is suggested that charge groups in the Lys–Asp derivatives are responsible for lipolytic action and the hydrophobic hydrocarbon chains in the derivatives enhance the ability to induce lipolysis or inhibit the gorwthhormone-mediated lipolysis.     

Properties of the Glucose Transport System in Some Deep-Sea Bacteria

Many deep-sea bacteria are specifically adapted to flourish under the high hydrostatic pressures which exist in their natural environment. For better understanding of the physiology and biochemistry of these microorganisms, properties of the glucose transport systems in two barophilic isolates (PE-36, CNPT-3) and one psychrophilic marine bacterium (Vibrio marinus MP1) were studied. These bacteria use a phosphoenol-pyruvate:sugar phosphotransferase system (PTS) for glucose transport, similar to that found in many members of the Vibrionaceae and Enterobacteriaceae. The system was highly specific for glucose and its nonmetabolizable analog, methyl alpha-glucoside (a-MG), and exhibited little affinity for other sugars tested. The temperature optimum for glucose phosphorylation in vitro was approximately 20°C. Membrane-bound PTS components of deep-sea bacteria were capable of enzymatically cross-reacting with the soluble PTS enzymes of Salmonella typhimurium, indicating functional similarities between the PTS systems of these organisms. In CNPT-3 and V. marinus, increased pressure had an inhibitory effect on a-MG uptake, to the greatest extent in V. marinus. Relative to atmospheric pressure, increased pressure stimulated sugar uptake in the barophilic isolate PE-36 considerably. Increased hydrostatic pressure inhibited in vitro phosphoenolpyruvate-dependent a-MG phosphorylation catalyzed by crude extracts of V. marinus and PE-36 but enhanced this activity in crude extracts of the barophile CNPT-3. Both of the pressure-adapted barophilic bacteria were capable of a-MG uptake at higher pressures than was the nonbarophilic psychrophile, V. marinus.     

Isolation and Some Properties of Alkalophilic Bacteria Utilizing Rayon Waste

Bacillus No. C-11 which utilized rayon waste was isolated. This strain belongs to the genus Bacillus from its morphological and biochemical characteristics but grew better in alkaline media than in neutral media. Residual sugars of rayon waste were 34.7 % after 2 days cultivation, 25.5% after 4 days and 7.0% after 9 days. Yeast extract and N-source, such as polypeptone or urea stimulated the utilization of rayon waste. The long period cultivation optimum pH was about 11, and the short period cultivation optimum pH was about 9. Partially purified hemicellulase from Bacillus No. C-11 was most active at pH 7, but still active at pH 10. The stable pH for this enzyme action was in the range of 5.5 to 9, and from the hemicellulose enzymatic digest, xylose, xylobiose, xylotriose and oligosaccharides were detected.     

Cellular Location and Some Properties of Proteolytic Enzymes of Rumen Bacteria

Several physical and chemical techniques were used to extract, and to identify the location of, proteolytic enzymes associated with mixed rumen bacteria. Most activity was removable by gentle physical methods such as shaking and brief blending, without cell disruption, indicating that it was associated with coat and capsular material. Proteases were present also in the cell envelope, corresponding to the inner membrane fraction of gram-negative bacteria, and intracellularly and were removable by detergent and French press treatment. Temperature and pH profiles were obtained for the coat enzymes, likely to be the most important in the digestion of food protein. Inhibition studies indicated that these proteases, and those of the whole bacterial fraction from rumen fluid, were predominantly of the cysteine protease type.     

Properties of Alginate Lyases from Marine Bacteria

Alginate lyases (EC 4.2.2.3) from two marine bacteria were isolated and partially characterized. A cell-bound lyase from isolate A3 had a molecular weight of approximately 100,000 and cleaved mannuronate blocks, apparently in an exo manner. A lyase recovered from the culture medium of isolate W3 was soluble in saturated ammonium sulfate, cleaved guluronate blocks, apparently in an endo manner, and had a molecular weight of 35,000. The thiobarbiturate test and urea-polyacrylamide gel electrophoresis were used to determine substrate specificity and mode of substrate cleavage by the enzymes.     

Properties of Bacteria Isolated from Deep-Sea Sediments

Thirty-eight isolates were subjected to taxonomic analysis by computer. Of the 38 isolates, 31 were from sediment samples collected at depths from 9,400 to 10,400 meters in the Philippine and Marianas Trenches of the Pacific Ocean, and 7 cultures were from seawater samples collected at various depths from surface to 4,000 meters and from several locations in the Pacific Ocean. A total of 116 characteristics were determined for each isolate, coded, and transferred to punch cards. Similarity values were obtained by computer analysis, with the use of two recently developed computer programs. Five distinct phenetic clusters were observed from the numerical analyses. Four of the clusters were identified as species of the genus Pseudomonas, and one, as an aerogenic species of Aeromonas. Group IV was identified as pigmented Pseudomonas fluorescens, and the major cluster, consisting of groups I and II, which merged at a species level of similarity, was treated as a new species of Pseudomonas. The 38 strain data were compared with data for 132 marine and nonmarine strains previously subjected to computer taxonomic analysis. The barotolerant deep-sea strains, with the exception of the deep-sea P. fluorescens isolates, clustered separately from all other marine strains.     

几株乳酸菌益生潜力及降胆固醇的研究

采用体外试验方法研究7株乳酸菌和双歧杆菌对人体消化道不良环境的抵抗能力、在肠道上皮的黏附定植能力及其降胆固醇潜力。结果表明:受试菌对CCL-187细胞粘附能力存在显著差异(P<0.05),粪肠球菌M1粘附能力最强;各菌对胃液和胰液都有较强耐受能力,在模拟胃液和胰液中分别培养3h和4h后仍能保证95%以上存活;在含胆汁培养基中受到不同程度抑制,但都能存活;受试菌在生长过程中能够使环境中胆固醇降低从25%～54%不等,粪肠球菌A30和A31和嗜酸乳杆菌A878和PB1能使胆固醇降低40%以上,是良好的降胆固醇备选菌株。     

细菌碱性果胶酶的酶学特性及其应用研究

碱性果胶酶是最适作用pH值在碱性范围的果胶酶,由于其在碱性环境下活性较高的特点,在纺织和造纸等领域有良好的应用前景。从分子特性和催化特征等方面综述了源自野生菌和重组菌的细菌碱性果胶酶的酶学特性,并介绍了碱性果胶酶在棉织物精练、生物制浆和诱导植物抗病等领域的最新应用。     

Purification and Some Properties of Candida albicans DNA Polymerases

Abstract

DNA polymerases of Candida albicans were purified to near homogeneity. Three well distinguished peaks of DNA polymerase activity (Enzyme I, II and III respectively) were obtained bv DEAE-Sephacel chromatography. This purification step was followed by column chromatographies on Sepharose 6B and denatured DNA-cellulose. The enzymes molecular mass and biochemical properties, including their inhibition by aphidicolin, were studied. Molecular mass was determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and was found to be 110 kDa for Enzyme I, 80 kDa for Enzyme II and 50 kDa for Enzyme III.     

Physiological Properties of Nitrogen-scavenging Bacteria from the Marine Environment

Nine selected strains of marine bacteria from the marine environment, although taxonomically heterogeneous in character, exhibited a capacity for prolonged growth on 'nitrogen-free' media; only one strain, a Klebsiella sp., fixed dinitrogen under any of a considerable range of test conditions. The non-nitrogen-fixing bacteria were able to scavenge low levels of nitrogenous materials, principally ammonia, from the atmosphere. Contrary to previous suggestions, this growth did not have an abnormally low cellular protein and nitrogen content. Some strains with apparently low intracellular protein contents, as determined on a cellular dry weight basis, showed accumulations of carbonaceous storage products which distorted the cytochemical analyses. Representative strains grown in chemostat culture showed a high affinity (i.e. low Ks values—0.35–0.52 μmol/1) for the NH₄+ ion, compared with Escherichia coli (1.75 μmol/1) and preliminary studies of their glutamine synthetases suggested that the affinities ( K_m values—0.25–0.29 μmol/1) of this enzyme for hydroxylamine were similar to the few values reported for other marine bacteria.     

Interdomain Conjugal Transfer of DNA from Bacteria to Archaea

Escherichia coli transforms the methanogenic archaeon Methanococcus maripaludis at frequencies ranging from 0.2 × 10⁻⁶ to 2 × 10⁻⁶ per recipient cell. Transformation requires cell-to-cell contact, oriT, and tra functions, is insensitive to DNase I, and otherwise displays hallmarks of conjugation.Conjugal transfer of DNA involves a specific set of transfer (tra) functions that mediate the mobilization of DNA containing an origin of transfer (oriT) from a donor to a recipient in a process requiring cell-to-cell contact (9). While conjugation is often very efficient between members of a given species or genus, it can also occur at a lower efficiency between phylogenetically distant microorganisms with structurally distinct cell surfaces. Escherichia coli, for example, mediates conjugal transfer of DNA to such diverse bacterial recipients as cyanobacteria (23), spirochetes (14), and a variety of Gram-positive bacteria (17, 22); E. coli even mediates conjugal DNA transfer to members of the domain Eukarya, such as to Saccharomyces cerevisiae (6) and mammalian (20) cells. Because of its broad range of potential recipients, conjugation has proven to be a valuable genetic tool (11) and may be an important mechanism of horizontal gene transfer and a driver of genome evolution (7). Conjugation-like DNA transfer has also been demonstrated in members of the domain Archaea (5, 15). However, conjugation between Bacteria and Archaea has not been demonstrated, despite the observation that many whole-genome sequences of Archaea harbor DNA that appears to be of bacterial origin (7).To investigate whether conjugation can occur between Bacteria and Archaea, the RP4 (IncPα group) conjugal-transfer system was used to attempt to mobilize DNA from E. coli to the anaerobic, methanogenic archaeon Methanococcus maripaludis strain S2 (21). The RP4 system was selected because previous work demonstrated that this plasmid supports the transfer of DNA from E. coli to phylogenetically distant recipients, including yeast (3) and mammalian (20) cells. Additionally, E. coli has been shown to successfully conjugate with strictly anaerobic bacterial strains (22). M. maripaludis was chosen as a recipient because it has growth parameters similar to those of E. coli and has readily available selectable markers (1). For all the experiments described, M. maripaludis was grown in liquid or solid (excluding cysteine) McCas medium (12), supplemented with 2.5 μg/ml puromycin (Pur) where appropriate, using standard anaerobic techniques (2). All plating for conjugation experiments, except for determination of viable-E. coli cell counts, was performed in an anaerobic chamber (Coy, Grass Lake, MI) with an atmosphere of 5:5:90 H₂-CO₂-N₂. E. coli was grown in Difco LB medium (Becton-Dickinson, Sparks, MD) supplemented where appropriate with 50 μg/ml kanamycin sulfate (Kan) and ampicillin (Amp).To interrogate conjugal DNA transfer between E. coli and M. maripaludis, a set of vectors that either contained or lacked cis-acting sites required for mobilization by RP4 transfer functions were constructed (Table ​(Table1).1). Each of these vectors contained a Pur resistance (Pur^r) gene cassette (pac) (4) flanked by ∼0.5 kb DNA homologous to regions 5′ and 3′ of the M. maripaludis nrpR gene (nrpR::pac), which allows for selection by Pur in M. maripaludis and provides sites for homologous recombination into the nrpR locus of the M. maripaludis chromosome. This construct was selected because it has previously been used to transform M. maripaludis to Pur resistance by recombination into the nrpR locus using a polyethylene glycol (PEG)-mediated transformation protocol (10, 18). After it was demonstrated that plasmids of the appropriate genotypes support conjugation from donor strain E. coli S17-1, which contains the RP4 trans-acting transfer (tra) functions on the chromosome via an integrated RP4-2-Tc::Mu-Km::Tn7 cassette (16), to E. coli recipient cells (Table ​(Table1;1; see also the supplemental material), we investigated whether these same donor strains could support DNA transfer to M. maripaludis.

TABLE 1.

Transformation of M. maripaludis by E. coli

Surface Properties of Bacteria from Different Wastewater Treatment Plants

The surface properties of the individual members of degradative biocommunities isolated from different laboratory and natural populations were characterized. The bacterial strains isolated from a given origin and degrading a given substrate varied with respect to their hydrophobic and electrostatic properties (e.g. contact angle, adsorption to hexadecane, isoelectric point, adsorption of anionic orcationic dyes). However, despite their specific surface characteristics, in most cases the net charge properties of different bacterial strains (characterized by the zeta potential profiles of the bacteria in relation to the pH) were found to be related to the substrate the bacteria were able to degrade as well as to the consortium the bacteria were isolated from. For one group of specialized bacteria, only oneor at most two characteristic zeta potential profiles were measured. Compared to the differences between different strains, the zeta potential profiles of individual strains were only slightly affected by either growth state or changes in the actual nutrient composition. Even if isolated strains were cultivated in standard nutrient broth for several months, only slight differences in the zeta potential profiles were measured. Only the isoelectric focusing experiments indicated thatcultivation in a complex medium favoured a progressively decreased uniformity of surface charge properties. Thus, measurement of zeta potential profiles under standardized conditions may be a useful means to compare the surface structures of bacteria from different origins.     

Extremely Rapid Extraction of DNA from Bacteria and Yeasts

A very simple and rapid method for extracting genomic DNA from Gram-negative bacteria, Gram-positive bacteria and yeasts is presented. In this method, bacteria or yeasts are lysed directly by phenol and the supernatant is extracted with chloroform to remove traces of phenol. The supernatant contains DNA that is suitable for molecular analyses, such as PCR, restriction enzyme digestion and genomic library construction. This method is reproducible and simple for the routine DNA extraction from bacteria and yeasts.     

Biotechnological Potential of Some Cold-Adapted Bacteria Isolated from North-Western Himalaya

Microbiology - In the present study, cold-adapted bacteria were isolated from soil, water and glacial ice samples collected from various geographical locations within the north-western Himalayan...     

工程菌酯酶B1的纯化及性质研究

工程菌酯酶B1降解酶经硫酸铵分级沉淀、DEAE SepharoseCL 6B离子交换柱层析、SephadexG 1 5 0凝胶过滤 ,得到了分离纯化 ,SDS PAGE鉴定为单一组分。经 1 2 .5 %SDS PAGE法测得分子量约为 5 6KD ,提纯倍数为33.3,收率为 1 7.9%,比活力为 74 .7U/mg。该酶的最佳作用条件是 37℃ ,pH =7.0 ,该酶作用于α 乙酸萘酯的Km为1 .35× 1 0 -3 mM ,Vmax为 2 .7× 1 0 4μ/ml。酶在pH6～ 9范围内较稳定 ,重金属Cu2 对该酶具有明显的促进作用 ,而SDS对酶具有抑制作用 ,对有机磷农药对硫磷 (1 6 0 5 )的降解率在 90min内达 91 .5 %。     

Isolation and Properties of New Photosynthetic Bacteria Isolated from Seawater

Three strains of purple nonsulfur photosynthetic bacteria were isolated from seawater. They showed the characteristic properties of Rhodobacter species. Their biochemical, physiological, and chemotaxonomical properties were different from those of previously known species.     

Properties of satellite DNA from Brassica nigra

The DNA components of B. nigra were preparatively separated by equilibrium ultracentrifugation in a CsCl density gradient, the buoyant density of the main component being 1,696 g . cm-3, that of the satellite component--1,704 g . cm-3. The properties of individual DNA fractions were investigated. Four major components could be observed on the differential melting curve of satellite DNA. Using the reassociation kinetics method it was shown that 30% of satellite DNA are presented as a fast reassociating component with a length of a repeated unit of approximately 2,5 . 10(3) nucleotide pairs. The calculated values of Tm and buoyant density suggest that the m5C content in satellite DNA is lower than that in the main component. During equilibrium ultracentrifugation in the density gradients of actinomycin D--CsCl and Hg2+--Cs2SO4 the satellite DNA is split into 4 major components.