Biodiversity and extracellular enzymatic activity of heterotrophic bacterial communities in Bardawil Lagoon, Egypt

Abstract

The biodiversity of heterotrophic viable bacteria (209 isolates) in the hypersaline Bardawil Lagoon, Egypt, was studied. Composition and extracellular activities of viable culturable heterotrophic bacteria (VCHB) in the water and in non-colonised and seagrass-colonised sediments of Bardawil Lagoon were determined bimonthly during 1997 and 1998. The average ± SD total Kjeldhal nitrogen was 1.69 ± 0.44 mg l−1 in water, 335.95 ± 19.22 mg kg−1 in colonised sediments, and 215.5 ± 16.0 mg kg−1 in non-colonised sediments. Exoenzymatic bacterial activity (glycosidase) presented a seasonal trend with average values of 1.02 ±0.16 μM cm−3 min−1 in colonised sediment samples and was 0.36 ± 0.27 μM cm−3 min−1 in non-colonised sediments. Mean of VCHB was 4 017 ± 565 cfu g−1 and 1 195 ± 242 cfu g−1 for colonised and non-colonised sediments, respectively. Bacterial isolates from Bardawil Lagoon water and sediments yielded a wide diversity of VCHB: a total of 209 different species, belonging to 13 genera from the water and 12 genera from the sediments.