Isolation, screening and characterization of microbes with potential application in the treatment of Kampala City Abattoir effluent

Abstract

In Uganda, all slaughterhouses including Kampala City Abattoir do not have wastewater treatment facilities despite national discharge standards that have been put in place. Therefore in order to pave way for the design of a proper treatment system for abattoir effluents, this study was carried out to: characterize the wastewater from Kampala City Abattoir; isolate and characterize microorganisms capable of secreting proteases, cellulases, amylases, and lipases; and to evaluate the characterized microbes for their ability to grow in a consortium. This study was carried out from June 2007 to June 2009. Wastewater samples were collected from Kampala City Abattoir twice a week from June 2007 to September 2007 and characterized using standard methods for the examination of water and wastewater. Characterization of the wastewater revealed that Kampala City Abattoir affluent is of high strength with COD of 8933±1194 mg/L; BOD5, 8125±1137 mg/L; TS, 9307±1037 mg/L; turbidity, 5404±831 FAU; NH4-N, 59.5±6.7 mg/L; TN, 307±44 mg/L; PO4¬3--P, 47.7±6.7 mg/L; TP, 107±15 mg/L; and EC, 1.27±0.1 mS/cm. It was observed that there were no seasonal differences in wastewater quality. The pollutant concentrations are much higher than discharge standards set by National Environmental Management Authority (NEMA). This is because of poor slaughtering processes, which does not allow recovery of blood, manure, fats and meat pieces. The effluent impacts negatively on the environment where it is discharged, including Lake Victoria which is the final recipient of the effluent and therefore needed urgent intervention. As such, the information on the wastewater characteristics can be used to design a pilot wastewater treatment which can be used to treat abattoir effluent. Bacteria were isolated from soil samples collected from dumping sites from Lira, Soroti, Mbale and Kampala on nutrient agar and screened for secretion of the extracellular enzymes (proteases, lipases, cellulases and amylases) using pure substrates. Selected isolates were then characterized morphologically and physiologically using standard methods. A total of 465 bacterial strains were isolated most of which secreted at least one extracellular enzyme. Twenty nine isolates (KK14, KS19, KS59, OCS3, OCS25, WPO20, WPO21, WPO10, WPO11, WR11, KR26, KS32, MUF7, MUF10, MUF23, MUF24, MUF27, MUF29, MUF31, KS70, OCS9, KR16, WS13, KS23, MUF11, MUF12, MUF13, MUF15 and MUF21) were selected and characterized phenotypically. The characterization revealed that most of the isolates were gram positive motile rod-shaped bacteria capable of growing under both anaerobic and aerobic conditions. All the isolates were also catalase positive and grew in the temperature and pH ranges of 200C to 400C and 6.0 to 7.5 respectively. Whereas all isolates grew on all nitrogen sources tested, 7 isolates did not grow on at most three carbon sources tested. Of the twenty nine, isolates characterized, twelve (KS19, KS32, KS59, KS70, LD18, MUF24, MUF29, OCS25, KR22, WS5, KK14 and WPO21) were selected and tested for their ability to grow in a consortium. MUF24 and WS5 inhibited the growth of isolates WPO21 and MUF29, respectively. The phenotypic characteristics exhibited by these isolates suggest that the isolates belong to the genus Bacillus or related genera. However, further characterization using genetic methods is required in order to correctly identify them. Preliminary studies therefore indicated a high potential of the isolates KS19, KS32, KS59, KS70, LD18, MUF24, OCS25, KR22, WS5 and KK14 for the treatment of abattoir effluent. Besides, the bacteria characterize in this study can be novel sources of enzymes with industrial application. There is need to isolate, purify and characterize the enzymes.