Complete genome sequence of Arcanobacterium haemolyticum type strain (11018)

Arcanobacterium haemolyticum (ex MacLean et al. 1946) Collins et al. 1983 is the type species of the genus Arcanobacterium, which belongs to the family Actinomycetaceae. The strain is of interest because it is an obligate parasite of the pharynx of humans and farm animal; occasionally, it causes pharyngeal or skin lesions. It is a Gram-positive, nonmotile and non-sporulating bacterium. The strain described in this study was isolated from infections amongst American soldiers of certain islands of the North and West Pacific. This is the first completed sequence of a member of the genus Arcanobacterium and the ninth type strain genome from the family Actinomycetaceae. The 1,986,154 bp long genome with its 1,821 protein-coding and 64 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Non-contiguous finished genome sequence and description of Sulfurimonas hongkongensis sp. nov., a strictly anaerobic denitrifying,hydrogen- and sulfur-oxidizing chemolithoautotroph isolated from marine sediment

Here, we report a type strain AST-10 representing a novel species Sulfurimonas hongkongensis within Epsilonproteobacteria, which is involved in marine sedimentary sulfur oxidation and denitrification. Strain AST-10^T (= DSM 22096^T = JCM 18418^T) was isolated from the coastal sediment at the Kai Tak Approach Channel connected to Victoria Harbour in Hong Kong. It grew chemolithoautotrophically using thiosulfate, sulfide or hydrogen as the sole electron donor and nitrate as the electron acceptor under anoxic conditions. It was rod-shaped and grew at 15-35°C (optimum at 30°C), pH 6.5-8.5 (optimum at 7.0-7.5), and 10-60 g L^-1 NaCl (optimum at 30 g L^-1). Genome sequencing and annotation of strain AST-10^T showed a 2,302,023 bp genome size, with 34.9% GC content, 2,290 protein-coding genes, and 42 RNA genes, including 3 rRNA genes.     

羧甲基壳聚糖对口腔重要厌氧菌的抑菌性能评价

目的 :评价羧甲基壳聚糖对口腔重要厌氧菌的抑菌性能。方法 :选择与口腔疾病密切相关的厌氧菌 11株 ,采用梯度稀释法测定羧甲基壳聚糖的最低抑菌浓度 (MIC)。结果 :羧甲基壳聚糖对牙龈卟啉菌、放线共生放线菌、中间普氏菌、牙龈嗜二氧化碳纤维菌、黄褐嗜二氧化碳纤维菌、产黑色素普氏菌、白色念珠菌、牙髓卟啉菌、小齿普氏菌、变形链球菌、远缘链球菌、粘性放线菌的 MIC分别为 2 0 ,10 ,5,80 ,2 0 ,>80 ,2 0 ,5,2 0 ,10 ,60 ,40 mg/ml。结论 :羧甲基壳聚糖对多数与口腔疾病密切相关的厌氧菌有一定抑制作用 ,而对产黑色素普氏菌的抑菌性不明显     

云南哀牢山地区森林附生维管植物多样性及区系特征

附生植物作为山地森林生态系统中重要的结构性成分,在维持森林生态系统生物多样性格局、水分和养分循环等方面发挥着重要作用。本文通过野外调查、标本查阅并结合相关文献,对云南哀牢山地区附生维管植物物种组成及分布进行了系统研究。结果显示,哀牢山地区附生维管植物共有23科83属218种,其中附生蕨类和兰科植物最丰富。附生蕨类有34属93种,以附生-石生蕨类生活型占优势,其中水龙骨科17属62种,占附生蕨类的66.67%,瓦韦属(Lepisorus)和石韦属(Pyrrosia)分别有13种和10种。附生兰科植物有26属65种,其中石斛属(Dendrobium)和石豆兰属(Bulbophyllum)分别有12种和8种。该地区附生维管植物属的分布具有明显的热带性质并以热带亚洲分布居多。附生植物生长于生境因子变化剧烈、资源有限的林冠,对环境变化敏感,极易遭受破坏且破坏后难以恢复,不少附生植物具有很高的药用、观赏等价值。因此,应加强对附生维管植物这一特殊类群的保护。     

Isolation of Nitrogen Fixing Bacteria from Fungus Termites

Biological nitrogen fixation by the microorganisms in the gut of termites is one of the singularly important symbiotic processes, since termites invariably thrive on nitrogen poor diet. Two isolates of free living aerobic and facultative anaerobic N fixing bacteria were obtained from the guts of fungus cultivating termite, Macrotermes sp. Among the total bacterial isolates from termite gut, the per cents of N fixing aerobes viz., Azotobacter and Beijerinckia spp were 49% and 37% from the salivary gland while facultative N fixing anaerobe viz., Klebsiella and Clostridium contributed (51% and 93%). The free living aerobic bacteria were identified as Azotobacter spp (19 x 10⁴ CFU mL^‐1) and Beijerinckia (13.2 x 10⁴ CFU mL^‐1) from the salivary gland of the termite; interestingly, foregut, mid gut and hind gut registered a low population of these bacteria. The isolates of Azotobacter were smooth, glistening, vicid in nature, rods, gram negative and cyst forming. Isolates of Beijerinckia sp. produced copious slime, tenacious, rods, gram negative with no cyst formations. Both the isolates emitted green fluorescence and produced acid. Facultative N fixing anaerobes were harbored in the hind gut. The isolates were identified as Klebsiella (20 x 10⁴ CFU mL^‐1) and Clostridium pasteurianum 39.1 x 10⁴ CFU mL^‐1. Klebsiella were straight rods arranged singly or in pairs, non‐motile, gram negative, whereas Clostridium pasteurianum was viscoid, motile with terminal spores. A positive correlation was observed between the extractable polysaccharides of these isolates and soil aggregation. The aggregates formed by the isolates increased soil aeration, porosity, water holding capacity and helped in better plant growth. Thus, the gut microflora of termite, apart from harnessing nitrogen from the atmosphere, also helps improving soil fertility.     

Effect of live and heat-killed bacteria on the secretory activity of Paneth cells in germ-free mice

Summary Germ-free mice were given live or heat-killed facultative anaerobes, and the ultrastructure of ileal Paneth cells was quantitatively examined with special reference to secretory granules showing a bipartite substructure (central core and peripheral halo). After administering live or heatkilled bacteria, there was a decrease in the area occupied by the cores of secretory granules in Paneth cells, and exocytosed core material was observed in the crypt lumen. There were no changes in the area occupied by the halo of secretory granules. None of the examined Paneth cells phagocytosed bacteria. It is concluded that certain bacteria may affect the secretion of antibacterial agents contained in the secretory granules of Paneth cells.     

Aerobic and anaerobic metabolism in a facultative anaerobe Ep01 lacking cytochrome, quinone and catalase

Abstract A facultative anaerobe, strain Ep01 produced a mixture of pyruvate, formate, acetate and ethanol from glucose anaerobically, and acetate and pyruvate aerobically. Cell extract of anaerobic-grown cells contained active pyruvate formatelyase, aldehyde dehydrogenase and alcohol dehydrogenase, while cell extract of aerobic grown cells contained an active pyruvate dehydrogenase system, NaDH oxidase and NADH peroxidase. Levels of acetate kinase and phosphate acetyltransferase activities were not significantly different in cells grown under either condition. Based on the metabolic products and the emzyme activities, we propose the presence of two metabolic pathways in strain Ep01, namely, a pathway to form formate, acetate and ethanol under anaerobic conditions, and a pathway to form under aerobic conditions. This explains why strain Ep01 can grow well both under strictly anaerobic conditions and well-aerated conditions.