Promising microorganisms for treatment of poultry processing wastewater

Abstract

Massive volumes of effluents discharged by the poultry-processing plants contain elevated levels of pollutants (dissolved keratins, blood, lipids and proteins), and are distinguished by high BOD and COD values, as well as by large concentrations of suspended particles [1]. Therefore, there is an urgent need to develop effective and eco-safe methods protecting the environment from contamination. Among such methods the application of efficient microbial degraders of toxicants, possessing enhanced flocculating and decomposing activity, that can be introduced into the decontamination units to supplement the microbiota of the activated sludge at various stages of treatment, seems to be especially promising. Currently, biopreparations of microbial consortia intended for remediation of the environments exposed to organic pollutants are widely spread. The most common constituents of such consortia represent such genera as Rhodococcus, Bacillus, Pseudomonas, Arthrobacter, etc. [2]. Our study was focused on the microorganisms of the Rhodococcus and Bacillus genera, which are able to utilize the organic compounds in the poultry processing wastewater. There were selected 14 variants out of 145 screened strains that were either deposited in the laboratory of environmental biotechnologies, Institute of Microbiology, NAS of Belarus, or isolated from effluents of poultry-processing plants. They were tested for the COD degradation activity in poultry-processing wastewater, assayed for the proteolytic and lipolytic activities [3], and estimated for the biosurfactant forming potential [4]. The degradation activity of the selected microbial cultures was investigated using poultry-processing effluents with initial COD value of 1144 O2/dm3. It was found that the top COD reduction was by B. subtilis 6/2-APF1, B. coagulans 1710, Bacillus sp. FL-9MV, Bacillus sp. FL X-5, Bacillus sp. PF1, R. ruber 30P, R. ruber 200N, R. ruber 1NG – 52,3-71,6%. The maximum proteolytic activity toward milk proteins was observed for B. coagulans 1710, B. subtilis 6/2-APF1, Bacillus sp. FL-9MV, Bacillus sp. FL X-5. The lipolytic activity on the tributyrin-containing medium was detected in all 14 tested strains – B. coagulans 1710, B. subtilis 6/2-APF1, Bacillus sp. FL-9MV, Bacillus sp. FL X-5, Bacillus sp. PF1, R. erythropolis 7D, R. erythropolis 23F, R. erythropolis 70F, R. ruber 2B, R. ruber 1NG, R. ruber 30P, Rhodococcus sp. P1, Rhodococcus sp. G13, R. ruber 200N with the last two being especially active. The highest capacity to produce biosurfactants in the specific nutrient medium with methylene blue was displayed by B. coagulans 1710, B. subtilis 6/2-APF1, Bacillus sp. FL-9MV, Bacillus sp. FL X-5. In addition, the ability to produce surface active agents was observed for the bacterial cultures of Bacillus sp. PF1, R. ruber 2B, Rhodococcus sp. R1-3FN, Rhodococcus sp. G13 and R. erythropolis 7D. Among the tested bacterial strains, the following cultures proved to be the most effective in decontamination of the poultry-processing wastewater: B. coagulans 1710, B. subtilis 6/2-APF1, Bacillus sp. FL-9MV, Bacillus sp. FL X-5, Bacillus sp. PF1. The above-listed microorganisms may act as promising components of the biopreparations promoting decontamination of the poultry-processing effluents.