Polyphasic Taxonomy Of Three Marine Bacterial Strains

In this thesis, three marine bacterial strains isolated from the sediments of the West Pacific were studied using modern polyphasic taxonomy methods. On the basis of morphogical and chemotaxonomic properties and phylogenetic analysis based on 16S rDNA sequence data, it is proposed that three marine bacterial strains should be classified in a novel genus or a novel species. The main results are as follows:(1) Cells of strain GY0574T is Gram-positive, non-motile and aflagellate. After cultivation on modified 2216E medium at 28℃ for 4 days, cells are rod-shaped, 0.4-0.6μm×0.7-1.2μm in size, and occur in pairs or in short chain. Colonies are 0.5 mm in diameter, opaque, smooth, slight convex, circular with regular margins and light yellow in color after cultivation on modified 2216E medium at 28℃ for 7 days., The tolerant and optimal growing conditions of strain GY0581T are 15-40℃ and 35-37℃ in temperature,5-9.5 and 7-8 in pH,0-13% and 3.5-7% in salinity, respectively. Based on 16S rRNA gene sequence similarity analysis, strain GY0581T is most closely related to Lentibacillus juripiscarius IS40-31 (95.81%) and Virgibacillus soli CC-YMP-6T (95.36%). The predominant polar lipids are diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, unknown glycolipid and unidentified phospholipids. The main mainquinone is MK-7. Main fatty acids are dominated by iso-C16:0 (34.97%) and anteiso-C15:0 (32.56%). The G+C content of the genomic DNA is 42.6%. On the basis of the phenotypic, chemotaxonomic and molecular data, strain GY0574T is considered to represent a novel genus and species, for which the name Brevilentibacillus brevis is proposed. The type strain is GY0574T(=MCCC 1A10572T).(2) Cells of strain GY0565T is Gram-negative. After cultivation on modified 2216E medium at 28℃ for 4 days, cells of this strain are rod-shaped, about 0.4-0.6× 0.7-1.5μm in size, and occur in pairs or in short chain status. Colonies are I mm in diameter, opaque, smooth, slight convex, circular with regular margins and orange red in color after cultivation on modified 2216E medium at 28℃ for 7 days. Their tolerant and optimal growing conditions are 4-40℃ and 30-35℃ in temperature.3-10 and 7-9 in pH,0-14% and 3.5% in salinity, respectively. Based on 16S rRNA gene sequence similarity analysis, it is most closely related to the known type strains Hephaestia caeni ERBI-3T (95.82%) and Sphingomonas indica Dd 16T (95.08%). The predominant polar lipids are diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, unknown glycolipid, and phosphatidylglycerol. The main mainquinone is Q-10. Main fatty acids are dominated by Summed Feature 8 (C18:1w7c and/or C18:1 w6c,35.34%) and C17:1 w6c (35.09%). The G+C content of the genomic DNA is 68.2%. On the basis of the phenotypic, chemotaxonomic and molecular data, strain GY0565T is considered to represent a new genus and species, for which the name Sphingobacter tangerine is proposed. The type strain is GY0565T (=MCCC 1A105691).(3) Cells of strain GY0581T is Gram-negative, non-motile, and aflagellate. After cultivation on modified 2216E medium at 28℃ for 4 days, cells of this strain were spherical with about 0.4-0.5×0.4-0.5μm in diameter. Colonies are 2 mm in diameter, opaque, smooth, slight convex, circular with regular margins and orange in color after cultivation on modified 2216E medium at 28℃ for 7 days. Their tolerant and optimal growing conditions are 15-40℃ and 35-37℃ in temperature,5-10.5 and 7-8 in pH, 0-6% and 3.5% in salinity, respectively. Based on 16S rRNA gene sequence similarity analysis, it is most closely related to the strain Paracoccus sediminis KMB17T (98.1%). The predominant polar lipids are phosphatidyl methyl ethanolamine, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, unidentified aminolipid unidentified phospholipids, and unknown glycolipid. The main mainquinone is Q-10. Main fatty acids are dominated by Summed Feature 8 (C18:1w7c and/or C18:1w6c,79.46%) and C18:0 (9.44%). The G+C content of the genomic DNA is 67.1%. On the basis of the phenotypic, chemotaxonomic and molecular data, strain GY0581T is considered to be a new species attributed to Paracoccus, for which the name Paracoccus croci is proposed. The type strain is GY0581T (=MCCC 1A10575T).