AEROBIC HETEROTROPHIC BACTERIA ISOLATED IN FRONT OF RHONE OUTLET .2. ORGANIC SUBSTRATES SUPPORTING GROWTH

Strains of bacteria (200) were isolated from eutrophic surface waters; the substrates used as the sole C source were screened within 100 organic compounds belonging to different chemical groups. The fatty acids are the most frequently used substances, being attacked by 55% of the strains. The other compounds are ordered as follows: aliphatic amino-acids (51%), miscellaneous amino-acids (44%), hydroxyacids (43%), dicarboxylic acids (42%), miscellaneous organic acids (30%), carbohydrates (28%), carbohydrate derivatives (27%), alcohols (21%), and organic bases (19%). Most of the strains attack numerous substrates, but none of these substrates is used by all the bacteria. From the data reported and from those in the literature, it can be stated that proline, glutamate, pyruvate and succinate are attacked by most of the bacteria sampled both from surface waters and from neritic or deep sea sediments. The measurements of the bacterial heterotrophic assimilation rate should be run using these compounds instead of glucose.