ASSESSMENT OF BIOFLOCCULANT PRODUCTION BY FRESHWATER BACTERIA RECOVERED FROM SEDIMENT OF OLE RIVER, ETSAKO WEST LOCAL GOVERNMENT AREA, EDO STATE. NIGERIA.

Bioflocculant production by microorganisms has been studied from the perspective of its biotechnological potential. Bacteria utilizes available nutrients in the culture media to synthesize high molecular weight polymers under the action of specific enzymes, and these polymers can be excreted into the external environment which may serve varied purpose. In this study, fresh water and sediments from Ole River were screened for bacteria with bioflocculant producing capabilities and subjected to different culture and optimization condition.

Surface water and sediment samples were collected from Ole River, Etsako West Local Government Area, Edo State Nigeria using sterile plastic containers and analysed for bacterial isolation. The flocculating activity was determined using Kaolin clay as the suspended solid. The effects of different carbon and nitrogen sources on bioflocculant activity in the test bacteria were assessed using standard procedures. Time course experiment, purification and characterization of the bioflocculant were also assessed using standard method. Polymerase chain reaction and sequencing approach were used to confirm the identity of the bioflocculant-producing bacteria species.

Over seventy-eight, freshwater bacteria were isolated and characterized from the Ole River in Etsako West Local Government Area Nigeria and were screened for bioflocculant production. The analytical profile index (API 20 NE) system assigned the bioflocculant-producing strains to Enterococcus sp. (99 %) and Xanthomonas sp. (100 %). Enterococcus sp. and Xanthomonas sp. effectively utilized sucrose as an organic carbon source for bioflocculant-production with flocculating activities of more than 80 % and 60 % except for starch which showed flocculating activity slightly above 21 % and 11 % respectively. Fructose was a favourable carbon source for Enterococcus sp. with flocculating activity above of 92 % while glucose was a favourable carbon source for Xanthomonas sp. with flocculating activity above 87 %. Enterococcus sp. and Xanthomonas sp. effectively utilized peptone and NH₂SO₄ as nitrogen sources for bioflocculant-production with flocculating activities of 92.2 % and 64.7 %. Enterococcus sp. and Xanthomonas sp. effectively utilized Mg²⁺ and Mn²⁺ as cations sources for bioflocculant-production with flocculating activities of 82.6 %, 63.2 % and 75.2 %, 64.1 % respectively. Effective bioflocculant production for Enterococcus sp. was observed between pH 4-7 with reduced to no bioflocculant production above pH 8; while bioflocculant production for Xanthomonas sp. was observed between pH 4-11. An increase in concentration dose significantly impacted the  production of the bioflocculant from 0.1 to 0.4 0.1 to 1 mg/mL for Enterococcus sp. with persistent decrease from 0.5 to 1. However, increase in concentration dose significantly impacted production of the bioflocculant from 0.1 to 1 mg/mL for Xanthomonas sp. Inoculum size for Enterococcus sp. and Xanthomonas sp. significantly impacted flocculating activity from 1 to 4 % (v/v) with a sharp decrease in flocculating activity from 5 % (v/v). A detailed characterization of the purified bioflocculant as well as development of process condition for large scale production for pilot field trials are required and are a subject of further investigation.