EFFECT OF MARINE ENVIRONMENTAL-FACTORS ON THE GROWTH-RATE AND RESPIRATORY ACTIVITY OF BACTERIA UTILIZING HYDROPHOBIC SUBSTRATE

The effect of shifting salinity and pH to values typical of seawater o n hydrocarbon-oxidizing bacteria residing in a nonsaline medium was in vestigated. The studied parameters of the physiological state were the respiratory activity and growth rate. The bacteria were grown on diff erent substrates, either hexadecane or glucose. An abrupt increase of salinity to 3% NaCl caused a sharp decrease of endogenous respiration both in glucose- and hexadecane-grown cells of Pseudomonas aeruginosa. Exogenous respiration remained active. Upon a sudden rise of pH to 8. 5, endogenous respiration did not diminish, but the response to the ad dition of glucose vanished. With combined action of both factors, thei r negative effects were cumulative. This tendency, although less expre ssed quantitatively, was also encountered in Arthrobacter ceroformans cells. Cultivation at increased values of salinity and pH showed that the observed changes in the growth characteristics depended upon the t ype of the growth substrate and the affinity of the studied bacteria f or it.