FiveS rRNA sequences and fatty acid profiles of colourless sulfur-oxidising bacteria

Abstract

Colourless sulfur-oxidising bacteria have been encountered extensively in the oxygen minimum layers of the Arabian Sea. These oligotrophs have been known to mediate nitrogen cycle reductively even under autotrophic conditions. Some of these organisms have defied identification by API (Appareils et Procedes d'Identification) and biology systems. Hence, computer-aided MIS (Microbial Identification System) has been used to define their relatedness through fatty acid profiles. To characterize these at the molecular level, 5S ribosomal ribonucleic acid (5S rRNA) sequences have been determined. Fatty acid profiles showed strain 29 to be related to Pseudomonas vesicularis with an E.D. of 5.965 and similarity index of 0.182. The nearest organism of strain 82 was Pediococcus halophlus with an E.D. of 27.5 with very little similarity. Visual comparison of 5S rRNA sequences with other G-ve organisms that were intuitively chosen for their relatedness showed that both these isolates have the greatest homology (82.5%) with Alcaligenes faecalis