Culturability of hydrocarbon degrading bacteria on a developed medium

الملخص EN

The majority of microbes in environmental samples cannot be cultured in laboratory media which are biased for the growth of specific microorganisms.

In light of this, molecular biological techniques offer new opportunities, for example denaturing gradient gel electrophoresis (DGGE) allows us to directly determine the presence and relative levels of different 16S rRNA gene amplicons both qualitatively and semi qualitatively in order to perform community analysis.

The first goal of this study was to determine the efficiency of the novel minerals- silica gel- oil medium (MSO) for the cultivation of a broad spectrum of hydrocarbon degrading bacteria.

Therefore, it was necessary to examine the bacterial culturability in different sea water samples.

The second goal of this study was to determine the effect of enrichment of marine bacteria at different levels of hydrocarbons on their culturability.

The examined MSO medium was composed from light Balaeem base oil as a sole source of carbon and energy adsorbed on activated silica gel and incorporated into agar medium containing mineral salts.

In order to examine the culturability of different species on the developed medium, denaturing gradient gel electrophoresis (DGGE) profiles of the 16S rDNA PCR product of each sea water sample was compared to that of the whole grown colonies on the MSO medium for the same sample.

Among 20 microcosms representing different enrichments of marine biodegrading microorganisms, the DGGE profiles revealed variable culturability on the MSO medium for different enrichment microcosms.

The culturability of the biodegrading bacteria exposed to different pollution conditions was found to be changeable.

It ranged between 51.2% and 92.9%, this indicates that MSO medium is very effective medium for the cultivation and enumeration of hydrocarbon degrading bacteria.

The hydrocarbon pollution level and history can affect the culturability of bacteria which inhabit such environment.

Biodegrading bacteria enriched or grown previously with high PAH concentration exhibited the highest culturabilities on MSO.