Isolation and characterization of novel marine agarolytic bacteria

• Main Authors: Tung Yen Liu, 劉東岩
• Other Authors: 謝文陽
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/80136851310008022654

碩士 === 國立臺灣大學 === 海洋研究所 === 94 === Agar, a complex polysacchrides extracted from red algae, consists of polygalactan. Polygalactan is composed of above 70% agarose and 30% agaropectin, and agarose consists of a linear chain of alternating residues of 3,6-anhydro-L-galactose and D-galactose. Only a relatively few bacterial species are capable of degrading this refractory material. Agarolytic bacteria are ubiquitous in coastal and estuarine habitats. In this study, there were 110 agarolytic marine bacteria isolated from northeast coast and An-Ping Harbor. Phenotypic and phylogenetic data of the isolates revealed that three isolates, TMA1, SA1, and AW18, could be novel species. These three agarolytic isolates were Gram-negative and straight or curved rods. They required NaCl for growth and presented catalase. They could reduce nitrate to nitrite but not further to N2. Other characteristics of the three isolates are listed below. TMA1 was non-motile and non-flagellated. It grew aerobically and was incapable of anaerobic growth by fermenting glucose or other carbohydrates. Cellular fatty acids were predominated by C16:0 (17.5%), C17:1ω8c (12.8%), C17:0 (11.1%), C15:0 iso 2-OH/C16:1ω7c (8.6%) and C13:0 (7.3%). The DNA G+C content was 41.0 mol%. The strain showed highest 16S rRNA gene sequence similarities to JAMB-A33 (98.2%), Thalassomonas ganghwensis (95.2%) and Thalassomonas viridans (94.7%). No other known bacteria shared more than 94% sequence similarity with strain TMA1. SA1 was non-motile and non-flagellated, but some cells were flagellated. It grew aerobically and was capable of anaerobic growth by reducing nitrite to nitrate. Cellular fatty acids were predominated by C15:0 2-OH/C16:1ω7c (28.6%), C17:1ω8 c (22.8%), C16:0 (14.5%), C18:1ω7 c (11.0%), and C17:0 (6.4%). The DNA G+C content was 55.6 mol%. The 16S rRNA gene sequence was similar to Teredinibacter turnerae (92.7%), Pseudomonas argentinensis (92.3%), and Cellvibrio japonicus (92.1%), and no other known bacteria shared more than 92% sequence similarity with strain SA1. AW18 could motion by a single polar flagellum. It was capable of anaerobic growth by fermenting glucose or other carbohydrates. The major fatty acids present at levels greater than 5% included C15:0 iso 2-OH/C16:1ω7c (35.62%), C18:1ω7c (27.03%), C16:0 (16.26%), C14:0 3-OH/C16:1 iso I (6.90%). The DNA G+C content was 52.9 mol%. The strain showed highest 16S rRNA gene sequence similarities to Agarivorans albus (93.9%), and no known bacteria shared more than 92% sequence similarity with strain AW18. Phylogenetic and phenotypic characteristics accumulated in this study support that TMA1, SA1, and AW18 are novel species in