Kistimonas alittae sp. nov., a gammaproteobacterium isolated from the marine annelid Alitta succinea.

A novel Gram-stain-negative, rod-shaped, motile, non-spore-forming, facultatively anaerobic marine bacterium was isolated from the gastrointestinal tract of the sandworm Alitta succinea collected from Grice Cove, South Carolina, USA. The strain was arginine dihydrolase-positive, and oxidase- and catalase-positive. Growth occurred between 10 and 37 °C, with optimal growth occurring between 30 and 32 °C. Comparative 16S rRNA gene sequence analysis showed its nearest neighbours are members of the genus Kistimonas of the family Hahellaceae, which is found in the order Oceanospirillales, class Gammaproteobacteria. The closest related species was Kistimonas asteriae KMD 001T with 16S rRNA gene sequence similarity of 99.0 %. However, DNA-DNA hybridization between these strains revealed less than 70 % DNA-DNA relatedness, supporting the novel species status of the strain. The major fatty acids were C16 : 0, C18 : 0, C18 : 1ω7c and a summed feature that contained C16 : 1ω6c/C16 : 1ω7c. The major respiratory quinone was ubiquinone-9 and the predominant polar lipids were phosphatidylserine, phosphoethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G+C content was 52.5 mol%. Based on the data presented, strain BGP-2T is considered to represent a novel member of the genus Kistimonas, for which the name Kistimonas alittae sp. nov. is proposed. The type strain is BGP-2T (=CCUG 65711T=JCM 30010T).

Isolation of surfactant-resistant bacteria from natural, surfactant-rich marine habitats.

Environmental remediation efforts often utilize either biodegradative microbes or surfactants, but not in combination. Coupling both strategies holds the potential to dramatically increase the rate and extent of remediation because surfactants can enhance the bioavailability of contaminants to microbes. However, many surfactants permeabilize bacterial cell membranes and are effective disinfectants. An important goal then is to find or genetically modify microorganisms that possess both desirable degradative capabilities and the ability to thrive in the presence of surfactants. The guts of some marine invertebrates, particularly deposit feeders, have previously been shown to contain high levels of biosurfactants. Our primary aim was to mine these natural, surfactant-rich habitats for surfactant-resistant bacteria. Relative to sediment porewaters, the gut contents of two polychaete deposit feeders, Nereis succinea and Amphitrite ornata, exhibited a significantly higher ratio of bacteria resistant to both cationic and anionic surfactants. In contrast, bacteria in the gut fluids of a holothuroid, Leptosynapta tenuis, showed surfactant susceptibility similar to that of bacteria from sediments. Analyses of 16S rRNA gene sequences revealed that the majority of surfactant-resistant isolates were previously undescribed species of the genus Vibrio or were of a group most closely related to Spongiobacter spp. We also tested a subset of resistant bacteria for the production of biosurfactants. The majority did produce biosurfactants, as demonstrated via the oil-spreading method, but in all cases, production was relatively weak under the culture conditions employed. Novel surfactant-resistant, biosurfactant-producing bacteria, and the habitats from which they were isolated, provide a new source pool for potential microorganisms to be exploited in the in situ bioremediation of marine sediments.