Amphipathic structure of theonellapeptolide-Id, a hydrophobic tridecapeptide lactone from the Okinawa marine sponge Theonella swinhoei

Theonellapeptolide-Id (TNLP), a cyclic tridecapeptide lactone, was crystallized from dimethylformamide-water solution. In the asymmetric unit, two peptide molecules were combined with solvent molecules, and the total molecular weight was over 3000 Dalton. The crystal structure including solvent molecules was finally determined at 0.80 A resolution using synchrotron radiation. The conformations of two independent molecules were similar to each other and were also similar to the previously reported structure (Doi, Ishida, Kobayashi, Deschamps and Flippen-Anderson, 1999, Acta Crystallogr Sect C, 55, 796-798). About 13 hydrated water molecules were found at disordered 19 sites; they were located at a certain region to avoid contact with aliphatic side-chains of peptolide in the crystal. The spatial disposition of the solvent molecules and peptides subsequently caused the formation of the amphipathic layer.     

Medium for Enhanced Growth of Bacteria from a Swine Manure Digester

Most bacterial strains isolated from a swine manure digester grew sufficiently to permit transfer of cultures, but not characterization. Substrates, crude extracts, growth factors, and electron acceptors were evaluated for growth promotion. The growth of all but one group of the isolates was substantially increased with a medium containing glucose, cellobiose, soluble starch, pyruvate, peptone, yeast extract, minerals, volatile acids, vitamins, hemin plus vitamins K₁ and K₃, sodium bicarbonate, cysteine, and digester fluid. The strains require both known and unknown factors (in crude extracts) for maximal growth.     

Culturable Actinobacteria from the Marine Sponge Hymeniacidon perleve: Isolation and Phylogenetic Diversity by 16S rRNA gene-RFLP Analysis

A total of 106 actinobacteria associated with the marine sponge Hymeniacidon perleve collected from the Yellow Sea, China were isolated using eight different media. The number of species and genera of actinobacteria recovered from the different media varied significantly, underlining the importance of optimizing the isolation conditions. The phylogenetic diversity of the actinobacteria isolates was assessed using 16S rRNA gene amplification–restriction fragment length polymorphism (RFLP) analysis of the 106 strains with different morphologies. The RFLP fingerprinting of selected strains by HhaI-digestion of the 16S rRNA genes resulted in 11 different patterns. The HhaI-RFLP analysis gave good resolution for the identification of the actinobacteria isolates at the genus level. A phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to seven genera of culturable actinobacteria including Actinoalloteichus, Micromonospora, Nocardia, Nocardiopsis, Pseudonocardia, Rhodococcus, and Streptomyces. The dominant genus was Streptomyces, which represented 74% of the isolates. Three of the strains identified are candidates for new species.     

Tolerance of Bacteria to High Concentrations of NaCl and Glycerol in the Growth Medium

When compared at similar levels of water activity, glycerol was more inhibitory than sodium chloride to relatively salt-tolerant bacteria and less inhibitory than salt to salt-sensitive species.     

The Intracellular Water Activity of Bacteria in Relation to the Water Activity of the Growth Medium

Intracellular water activities ( a _w) calculated from the solute composition of various bacterial cells, are in good agreement with values derived from intracellular freezing point data. Further, and confirming literature results based on freezing points, the intracellular a _w was found to be generally equal to or lower than that of the growth medium.     

含无机盐沉淀菌悬液中微生物生长量的快速测定

目的:消除菌悬液中无机盐沉淀对比浊法测定生长量的干扰。方法:以嗜有机甲基杆菌ME25为材料,采用比浊法,研究了EDTA对菌悬液中无机沉淀物的清除效应以及对菌体生物量测定的影响。结果:在室温、pH 4~11,1.25×10^-2 mol/L EDTA与菌悬液样品作用1min,即可去除样品中无机盐沉淀,样品稳定,在1h内不影响样品中菌体吸光度的测定;实际样品和理论样品测定,相对误差小于3.0%,回收率为98%~100%,RSD均小于0.5%。结论:采用螯合剂EDTA可快速去除菌悬液中的无机盐沉淀,有效地消除沉淀物的干扰,明显提高了比浊法测定生长量的准确度,简便易行,具有较高的实用价值。     

Enhanced Yields of Iron-Oxidizing Bacteria by In Situ Electrochemical Reduction of Soluble Iron in the Growth Medium

An electrochemical apparatus for culturing chemolithotrophic bacteria that respire aerobically on ferrous ions is described. Enhanced yields of the bacteria were achieved by the in situ electrochemical reduction of soluble iron in the growth medium. When subjected to a direct current of 30 A for 60 days, a 45-liter culture of Thiobacillus ferrooxidans grew from 6 × 10⁷ to 9.5 × 10⁹ cells per ml. Growth of the bacterium within the electrolytic bioreactor was linear with time. A final cell density corresponding to 4.7 g of wet cell paste per liter was achieved, and a total of 320 g of wet cell paste was harvested from one culture. The apparatus was designed to deliver protons concomitantly with electrons; therefore, the pH of the culture remained stable at 1.6 ± 0.1 for the duration of growth. This laboratory-scale apparatus may be readily adapted to pilot or production scale. It is thus anticipated that abundant numbers of iron-oxidizing bacteria may be obtained for both fundamental and applied studies.     

大莲湖池杉林湿地土壤可培养细菌的分离与鉴定

采用牛肉膏蛋白胨培养基培养,从大莲湖池杉林土壤中共分离得到20个菌落形态不同的菌株。通过对这些菌株的形态、培养特征、生理生化特征的研究以及16S rDNA序列分析,初步确定这些菌株分别属于假单胞菌属(Pseudomonas)、芽胞杆菌属(Bacillus)、红球菌属(Rhodococcus)、北里孢菌属(Kitasatosporia)、金黄杆菌属(Chryseobacterium)、不动杆菌属(Acinetobacter)、黄杆菌属(Flavobacterium)、鞘氨醇杆菌属(Sphingobacte-rium)和丛毛单胞菌属(Comamonas)等9个属细菌。其中芽胞杆菌属和不动杆菌属细菌是优势菌,分离到的红球菌属、北里孢菌属、鞘氨醇杆菌属和丛毛单胞菌属细菌在国内湿地土壤中报道较少。     

不同生境下五唇兰根部可培养内生细菌多样性研究

兰科植物内生细菌与菌根真菌的协作对宿主植物的生长、抗病、抗逆及植物修复环境能力等具有重要意义,揭示其内生细菌多样性及与生境之间的关系有助于阐明兰科植物的适应与进化机制。本研究基于16SrDNA序列分析探讨了不同生境下东南亚特有种五唇兰根部可培养内生细菌多样性及其空间异质性。结果表明:从不同生境下五唇兰根部共分离出内生细菌59株,其中从土生型五唇兰根部分离出内生细菌45株(76.27%),从石生型五唇兰根部分离出内生细菌14株(23.73%);基于内生细菌16SrDNA序列同源性分析及构建的系统发育树显示,五唇兰根部内生细菌分属于7属,即芽孢杆菌属(Bacillus)、伯克氏菌属(Burkholderia)、草酸菌属(Pandoraea)、土壤杆菌属(Agrobacterium)、类芽孢杆菌属(Paenibacillus)、泛菌属(Pantoea)、欧文氏菌属(Erwinia),其中优势属为芽孢杆菌属,次优势属为泛菌属和伯克氏菌属;多样性分析显示,土生型五唇兰根部内生细菌群落的Shannon多样性指数大于石生型五唇兰,不同生境下五唇兰根部内生细菌群落结构差异极显著(P0.01)。土生型五唇兰根部内生细菌群落优势属为芽孢杆菌属和泛菌属,石生型五唇兰根部内生细菌群落优势属为芽孢杆菌属和伯克氏菌属。     

A Medium for the Isolation of Capsular Bacteria from Kefir Grains

Secondary alcohols (C₃ to C₁₀) were oxidized to the corresponding methylketones by resting mycelia of Scedosporium sp. A-4 grown on propane, but 3-pentanol and 3-hexanol were not oxidized. The oxidation of 2-propanol to acetone was inhibited by pyrazole, potassium cyanide, sodium azide and Hg^{2 +}. Alcohol dehydrogenase activity was found in the cell-free soluble fraction and this activity requires a cofactor, specifically NAD⁺. The oxidation of both 1-propanol and 2-propanol may be catalyzed by the same alcohol dehydrogenase.     

Medium for the Selective Enumeration of Lactic Acid Bacteria from Foods

A nitrite actidione polymyxin agar was developed for the enumeration of lactic acid bacteria. It was effective in recovering organisms from pure cultures and from foods.     

Protozoan Response to the Addition of Bacterial Predators and Other Bacteria to Soil

Representatives of several categories of bacteria were added to soil to determine which of them might elicit responses from the soil protozoa. The various categories were nonobligate bacterial predators of bacteria, prey bacteria for these predators, indigenous bacteria that are normally present in high numbers in soil, and non-native bacteria that often find their way in large numbers into soil. The soil was incubated and the responses of the indigenous protozoa were determined by most-probable-number estimations of total numbers of protozoa. Although each soil was incubated with only one species of added bacteria, the protozoan response for the soil was evaluated by using most-probable-number estimations of several species of bacteria. The protozoa did not respond to incubation of the soil with either Cupriavidus necator, a potent bacterial predator, or one of its prey species, Micrococcus luteus. C. necator also had no effect on the protozoa. Therefore, in this case, bacterial and protozoan predators did not interact, except for possible competition for bacterial prey cells. The soil protozoa did not respond to the addition of Arthrobacter globiformis or Bacillus thuringiensis. Therefore, the autochthonous state of Arthrobacter species in soil and the survival of B. thuringiensis were possibly enhanced by the resistance of these species to protozoa. The addition of Bacillus mycoides and Escherichia coli cells caused specific responses by soil protozoa. The protozoa that responded to E. coli did not respond to B. mycoides or any other bacteria, and vice versa. Therefore, addition to soil of a nonsoil bacterium, such as E. coli, did not cause a general increase in numbers of protozoa or in protozoan control of the activities of other bacteria in the soil.     

Reduction of Aluminum Toxicity by Addition of a Conditioned Medium from Aluminum-Tolerant Cells of Carrot

The toxic effect of aluminum (Al) on the growth of Carrot cells(SO-l) decreased to a greater degree with addition of a mediumconditioned by Al-tolerant carrot cells (TA-l) than with a mediumconditioned by SO-l cells. The toxic effect of Al was reducedgreatly by adding an acidic fraction of the conditioned media,but little or not at all by a neutral or basic fraction. Offour organic acids detected in the acidic fraction, the majorone was citric acid which was present in a much greater amountin the conditioned medium of TA-l cells than in that of SO-lcells. The toxic effect of Al was reduced by adding citric or malicacid instead of the conditioned medium, but not by succinicor fumaric acid. Chelating abilities of the organic acids wereevaluated by shifts in their titration curves, and were foundto be closely correlated with the detoxification effects. Thus,the Al tolerance of TA-l cells may in fact be due to the chelatingeffect of citric acid which is abundantly released into themedium by the Al-tolerant carrot cells. (Received July 9, 1984; Accepted November 22, 1984)     

Changes in the Weathering Activity and Populations of Culturable Rock-Weathering Bacteria from the Altered Purple Siltstone and the Adjacent Soil

A total of 150 bacteria were isolated from the less and more altered (weathered) purple siltstones and the adjacent soils to compare the changes in the rock weathering patterns and populations of rock-weathering bacteria. The proportions of the highly effective Fe and Si solubilizers were significantly different among the altered rocks and soils. Maximum proportions of the highly effective Fe, Si, and Al solubilizers were observed in the soils, while significantly higher proportion of the highly effective K solubilizers was observed in the more altered rocks and the soils. The rock-weathering bacteria belonged to 37 bacterial species, among which 36, 64, and 56% of the species were specific to the less and more altered rocks and the soils, respectively. In the rock-weathering process, strains M78 and L38 mainly produced acetic acid, while strain H28 mainly produced gluconic acid. Furthermore, dominant rock-weathering members of Ensifer genus had the higher ability to release Fe and Si, while dominant rock-weathering members of Bacillus had the higher ability to release K. The results suggest the changes in the element mobilization patterns and populations of the rock-weathering bacteria and highlight the possible role of these bacteria in the rock weathering and soil formation.     

Isolation and Analysis of Bacteria with Antimicrobial Activities from the Marine Sponge Haliclona simulans Collected from Irish Waters

Samples of the marine sponge Haliclona simulans were collected from Irish coastal waters, and bacteria were isolated from these samples. Phylogenetic analyses of the cultured isolates showed that four different bacterial phyla were represented; Bacteriodetes, Actinobacteria, Proteobacteria, and Firmicutes. The sponge bacterial isolates were assayed for the production of antimicrobial substances, and biological activities against Gram-positive and Gram-negative bacteria and fungi were demonstrated, with 50% of isolates showing antimicrobial activity against at least one of the test strains. Further testing showed that the antimicrobial activities extended to the important pathogens Pseudomonas aeruginosa, Clostridium difficile, multi-drug-resistant Staphylococcus aureus, and pathogenic yeast strains. The Actinomycetes were numerically the most abundant producers of antimicrobial activities, although activities were also noted from Bacilli and Pseudovibrio isolates. Surveys for the presence of potential antibiotic encoding polyketide synthase and nonribosomal peptide synthetase genes also revealed that genes for the biosynthesis of these secondary metabolites were present in most bacterial phyla but were particularly prevalent among the Actinobacteria and Proteobacteria. This study demonstrates that the culturable fraction of bacteria from the sponge H. simulans is diverse and appears to possess much potential as a source for the discovery of new medically relevant biological active agents.