Changes in fatty acids of Pseudomonas nautica, a marine denitrifying bacterium, in response to n-eicosane as carbon source and various culture conditions

This study determined the effects of shifts in environmental conditions on the fatty acid composition of a sedimentary facultative anaerobic denitrify ing marine bacteria (Pseudomonas nautica strain IP 617). The effects of car bon source (n-eicosane, sodium acetate and rich medium), temperature (13, 2 0 and 30 degrees C), presence or lack of oxygen and growth phase (stationar y and exponential) were investigated. As demonstrated by correspondence ana lysis, the effect of the various conditions tested, in descending order of importance, were carbon source > temperature > growth phase greater than or equal to oxygen. Among the different growth substrates, n-eicosane (nC(20) ) led to the most distinct FA profiles, characterised by high amounts of sa turated and branched FA, the appearance of 20-carbon acids (20:1 omega 9 an d 20:0) and a Delta(10) methyl branched series with mainly the 10Me16:0, Wi th regard to temperature effects, P. nautica showed a mean acyl chain lengt h thermoregulation process for the major monounsaturated fatty acids which led to increased values of the ratio Sigma C-18:1/Sigma C-16:1 with increas ing temperatures. The effect of growth phase and anaerobiosis were less mar ked. The analysis of bacterial fatty acids could enable the detection of hy drocarbonoclastic bacterial communities in marine sediments contaminated by hydrocarbons. (C) 1999 Published by Elsevier Science B.V. All rights reser ved.