The taxonomic positions of three strains of marine gliding bacteria, TISTR 1736, TISTR 1741 and TISTR 1750T, isolated from the southern coastline of Thailand were evaluated by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the three isolates formed a distinct lineage within the family ‘Flammeovirgaceae’, phylum Bacteroidetes, and were related to the genus Flexithrix. The DNA G+C contents of the isolates were in the range 40–43 mol%. The major respiratory quinone was MK-7. The major cellular fatty acids were 16 : 1ω5c (cis-5-hexadecenoic acid) and 15 : 0 (pentadecanoic acid). The major hydroxyl fatty acids were 3-OH 17 : 0 (3-hydroxyheptadecanoic acid), 3-OH 15 : 0 (3-hydroxypentadecanoic acid) and 3-OH 16 : 0 (3-hydroxyhexadecanoic acid). On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic data, these marine bacteria are considered to represent a novel species of a new genus, for which the name Rapidithrix thailandica gen. nov., sp. nov. is proposed. The type strain of Rapidithrix thailandica is TISTR 1750T (=IAM 15448T).
Pre-treatment of stationary phase cells of Lactobacillus plantarum NCMIB 8826 with citric acid (pH 3 to 6) for a short period of time significantly improved subsequent cell survival in several highly acidic fruit juices namely cranberry (pH 2.7), pomegranate (pH 3.5), and lemon & lime juices (pH 2.8). Although the mechanism for this adaptation is still unclear, the analysis of the cellular fatty acid content of acid adapted cells and the reverse transcription polymerase chain reaction (RT-PCR) showed a significant increase (by ~1.7 fold) of the cellular cyclopropane fatty acid, cis-11,12-methylene octadecanoic acid (C) and a significant upregulation (~12 fold) of cyclopropane synthase (cfa) were observed, respectively, during acid adaptation. It is likely that these changes led to a decrease in membrane fluidity and to lower membrane permeability, which prevents the cells from proton influx during storage in these low pH fruit juices.
ABSTRACT:The mode of infection of Nomuraea rileyi in Spodoptera litura larvae was examined using local strains isolated from infected larvae of S. litura collected from the field in Mae Chaem district, Chiang Mai province, Thailand. Spore suspensions were topically applied to larvae followed by examination using standard histological techniques. Germ tubes penetrated through the cuticle surface within 48 hr after inoculation and then along the cuticle. Lysis of the endocuticle was found before hyphae penetrated and invaded the epidermis ca. 2.5 days after inoculation. The invasive hyphal stage then transformed into hyphal bodies that replicated within the hemocoel. These non-invasive hyphal bodies filled the hemocoel and then converted to invasive mycelia ca. 5-6 days after inoculation. At the end of the infection cycle, mycelium emerged from the cuticle and produced condiophores ca. 7 days after inoculation. The larvae became completely covered by white mycelium before turning green 1-2 days later as a result of spore production. The complete developmental cycle of N. rileyi in S. litura lasted approximately 8 to 9 days. List of abbreviations: List of abbreviations: List of abbreviations: List of abbreviations:List of abbreviations: bc, blood cell; Cu, cuticle; D, dermal cell; ed, endocuticle; ep, epicuticle; epd, epidermis cell; ex, exocuticle; FMAY, fish-soluble medium supplement with 1% maltose, 1% yeast extract and 1.5% agar; hb, hyphal body; hp, hyphae; m, muscle; µm, micron; nu, nucleus.
HeLa: cervical cancer HT-29: colon cancer KB: oral cancer MCF-7: breast adenocarcinoma PCR: polymerase chain reaction SK: skim milk medium SRB: sulphorodamine B Eighty-four marine gliding bacteria were isolated from specimens collected in the Gulf of Thailand and the Andaman Sea. All exhibited gliding motility and swarm colonies on cultivation plates and they were purified by subculturing and micromanipulator techniques. Their 16S rRNA genes were amplified by the polymerase chain reaction (PCR) technique. The phylogenetic analysis indicated that the represented isolates can be separated into six different clads (gr 1 -gr 6) within the Cytophaga-Flavobacterium-Bacteriodes (CFB) group. Group 1 formed a remote linear, with only 90% sequence similarity, from Flavobacteriaceae bacterium which indicated a potentially novel taxonomic group. Groups 2 and 3 were identified as the recently proposed Tenacibaculum mesophilum and Fulvivirga kasyanovii respectively. Groups 4, 5 and 6, consisting of the largest number of the members, were identified as Rapidithrix *Corresponding author thailandica, Aureispira marina and Aureispira maritima respectively. The isolates were cultivated in four different cultivation media (Vy/2, RL 1, CY and SK) and the crude extracts were submitted to screen cytotoxicity using a sulphorodamine B (SRB) assay. The results from cytotoxic screening showed that groups 2, 4 and 6 were capable of producing the cytotoxic metabolites against selected human cell lines (breast adenocarcinoma (MCF-7), colon cancer (HT-29), cervical cancer (HeLa) and oral cancer (KB)). However, groups 1, 3 and 5 did not produce metabolites with cytotoxicity when cultivated in the same cultivation media as the previous groups. CY medium was the only cultivation medium which could yield the cytotoxic metabolites against MCF-7.
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