PRELIMINARY STUDIES ON ECOLOGICAL DISTRIBUTION OF MICROORGANISMS IN WEST LAKE, HANGZHOU 2. Microorganisms in sediment

The abundance and distribution of microorganisms in the upper-layer sediment of West Lake were studied. Results showed that aerobic heterotrophic bacteria were 2.01 x 10⁵/g and actinomycetes were 1.83 x 10⁴/g on average. Both were more abundant in L. Yuehu. While the bacteria had negative correlation with the surrounding water temperature, actinomycetes had positive correlation. Aerobic cellulose decomposing bacteria were 1.88 x 10³/g on average, and more abundant in L. Xili and L. Yuehu L., peaking in July and May. Nitrite bacteria, nitrate bacteria, nitrate reducers and denitrifiers were 2.75 x 10⁵/g , 1.81 x 10⁵/g, 1.23 x 10⁵/g and 3.14 x 10³/g on average, respectively. Organic phosphorus decomposing bacteria were 2.38 x 10³/g on average, while calcium phosphate dissolving bacteria were very low. About 50.4% of heterotrophic bacteria were found to be Bacillus and about 23.9% were Enterobacteriaceae. Remain about 25.7% consisted of 11 other minor bacteria genus.Article信州大学理学部附属諏訪臨湖実験所報告 11: 59-66(1999)departmental bulletin pape

PRELIMINARY STUDIES ON ECOLOGICAL DISTRIBUTION OF MICROORGANISMS IN WEST LAKE, HUANGZHOU \n1. Microorganisms in the water body

The ecological distribution of microorganisms in the water body of West Lake was studied from April 1995 to April 1996. Results showed that the average density of heterotrophic bacteria was 2.06x10³/ml. Actinomycetes, molds and yeast had already of 35/ml, 24/ml and 2/ml, respectively. Various physiological forms of microbes were found in West Lake, including cellulose decomposing bacteria (25/ml), organic phosphorus decomposing bacteria (8/ml), and Nitrogen utilizing bacteria such as nitrite bacteria (453/ml), nitrate bacteria (585/ml), nitrate-reducers (3.2x10³/ml), and denitrifiers (43/ml). Contrasting to nitrate bacteria, cellulose decomposing bacteria, ammonifiers, nitrite bacteria and nitrate reducers were rich in winter and spring. Autotrophic bacteria, like nitrifiers were more common in L. Xiaonan and L. Beili, where the water quality was relatively good, Heterotrophic bacteria were populous in the two highly eutrophic lakes (L.Yuehu and L. Xili). The study on 78 strains isolated randomly from the five sub lakes suggested that the dominant groups in West Lake were Pseudomonas, Bacillus and Enterobacteriaceae.Article信州大学理学部附属諏訪臨湖実験所報告 11: 51-57(1999)departmental bulletin pape

Cloning and Characterization of Genes Involved in Nostoxanthin Biosynthesis of Sphingomonas elodea ATCC 31461

Most Sphingomonas species synthesize the yellow carotenoid nostoxanthin. However, the carotenoid biosynthetic pathway of these species remains unclear. In this study, we cloned and characterized a carotenoid biosynthesis gene cluster containing four carotenogenic genes (crtG, crtY, crtI and crtB) and a β-carotene hydroxylase gene (crtZ) located outside the cluster, from the gellan-gum producing bacterium Sphingomonas elodea ATCC 31461. Each of these genes was inactivated, and the biochemical function of each gene was confirmed based on chromatographic and spectroscopic analysis of the intermediates accumulated in the knockout mutants. Moreover, the crtG gene encoding the 2,2′-β-hydroxylase and the crtZ gene encoding the β-carotene hydroxylase, both responsible for hydroxylation of β-carotene, were confirmed by complementation studies using Escherichia coli producing different carotenoids. Expression of crtG in zeaxanthin and β-carotene accumulating E. coli cells resulted in the formation of nostoxanthin and 2,2′-dihydroxy-β-carotene, respectively. Based on these results, a biochemical pathway for synthesis of nostoxanthin in S. elodea ATCC 31461 is proposed

A Novel Strategy to Construct Yeast Saccharomyces cerevisiae Strains for Very High Gravity Fermentation

Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes

Gene cluster analysis for the biosynthesis of elgicins, novel lantibiotics produced by <it>paenibacillus elgii </it>B69

<p>Abstract</p> <p>Background</p> <p>The recent increase in bacterial resistance to antibiotics has promoted the exploration of novel antibacterial materials. As a result, many researchers are undertaking work to identify new lantibiotics because of their potent antimicrobial activities. The objective of this study was to provide details of a lantibiotic-like gene cluster in <it>Paenibacillus elgii </it>B69 and to produce the antibacterial substances coded by this gene cluster based on culture screening.</p> <p>Results</p> <p>Analysis of the <it>P. elgii </it>B69 genome sequence revealed the presence of a lantibiotic-like gene cluster composed of five open reading frames (<it>elgT1</it>, <it>elgC</it>, <it>elgT2</it>, <it>elgB</it>, and <it>elgA</it>). Screening of culture extracts for active substances possessing the predicted properties of the encoded product led to the isolation of four novel peptides (elgicins AI, AII, B, and C) with a broad inhibitory spectrum. The molecular weights of these peptides were 4536, 4593, 4706, and 4820 Da, respectively. The N-terminal sequence of elgicin B was Leu-Gly-Asp-Tyr, which corresponded to the partial sequence of the peptide ElgA encoded by <it>elgA</it>. Edman degradation suggested that the product elgicin B is derived from ElgA. By correlating the results of electrospray ionization-mass spectrometry analyses of elgicins AI, AII, and C, these peptides are deduced to have originated from the same precursor, ElgA.</p> <p>Conclusions</p> <p>A novel lantibiotic-like gene cluster was shown to be present in <it>P. elgii </it>B69. Four new lantibiotics with a broad inhibitory spectrum were isolated, and these appear to be promising antibacterial agents.</p