BACTERIAL ABUNDANCE, BIOMASS AND PROPORTION OF LIVING CELLS IN LITTORAL SANDY SEDIMENTS ON THE ROMANIAN BLACK SEA COAST

11th International Multidisciplinary Scientific GeoConference SGEM2011, www.sgem.org, SGEM2011 Conference Proceedings/ ISSN 1314-2704, June 20-25, 2011, Vol. 2, 995-1002 pp

ABSTRACT

Bacterial density, biomass, morphological diversity and cell integrity were studied in
surficial sediment samples taken form eight locations on the Romanian coast.
Investigation was done by epifluorescence microscopy, employing SYBR Green I
(universal fluorochrome) and propidium iodide (for visualising cells with damaged
membranes). Cell density varied between 4.62-9.64 × 107 cells/cm3 sediment, showing
a relation to sediment grain size. Dry biomass ranged between 3.03-6.39 μg/cm3. Rod
shaped bacteria were dominant (58-65%), the rods : cocci ratio also having a correlation
to sediment granulometry. A significant proportion of the microorganisms observed
lacked cell membrane integrity (i.e. dead cells).

Keywords: bacteria, abundance, biomass, membrane integrity, sandy sediments.