On the behaviour of pure cultures of marine micro-organisms in sterilized and re-inoculated sediments

Abstract

1. The behaviour of pure cultures of marine micro-organisms in sterilized sediments was studied by inoculation of the supernatant liquid media with mobile bacteria. 2. The largest numbers of bacteria developed at the sediment surface down to 4 mm depth and not in the supernatant liquid, in spite of the fact that the supernatant liquid only was inoculated. 3. Most of the strains tested reached the bottom of the sediment within a few days. 4. Strain 31 did not reach the bottom of the sediment in case of dry sterilisation of the sediment column. 5. Strain 31 developed in all media different coloured variants, except in media with additional sediment extract where the original red colour remained. In these media bacteria reached well to the bottom of the sediment columns tested. 6. The original organic matter of the sediment fractions tested was usually sufficient to support growth of the bacteria examined. After several days of incubation, bacteria reached the same numbers as was the case with additional nutrient substances. 7. Active movement of bacteria through fine grained sediments is possible. Population of sterile sediments from the supernatant water column is possible and progresses rapidly. 8. Decrease in bacteria numbers with increasing sediment depth is not connected to nutrient concentration.