Characterization of the black and white waters of the Manjolo Springs.

Abstract

The Manjolo springs are found in Binga in the Matebeleland North Province of Zimbabwe. The springs are twin springs separated by a 15 meter distance. One spring has black coloured water while the other has white coloured water. The study was undertaken to characterize the waters from both springs. Water chemical analysis to determine levels of metals, pH , total dissolved solids, electrical conductivity and nitrates in the water showed that levels of these parameters are closer to drinking water WHO guidelines, of note are the high levels of iron and nitrates in both Manjolo Black Water (MBW) and Manjolo White Water (MWW). The waters were cultured on Luria Bertani agar and a total of twenty isolates were recovered from the two springs. Gram stain of the isolates demonstrated that the isolates were all Gram negative rods but of varying sizes, staining intensities and spatial arrangements. Based on the culture methods, MBW had higher species diversity, with a total of eleven isolates, than the MWW which had a total of nine isolates recovered. Biochemical assays on the isolates showed presence of extracellular enzymes such as amylases, xylanases and lipases in some of the isolates. Antimicrobial activity was also observed in some of the isolates. Amplification of the 16S rRNA gene by bacteria specific 27F and 1492R universal primers was successful with all the twenty isolates demonstrating that all the isolates were bacteria in nature. Molecular profiling and phylogenetic analysis differentiated all the isolates as different species except for isolates 1 and 3 from the MWW. These were identified as identical species. The 16S rRNA gene sequences identified isolate 5 and 6 from MBW and isolates 8 and 9 from MWW as Morganella morganii of different strains. Isolate 2 from MWW was identified as Aeromonas hydrophila, isolate 4 from MWW as Enterobacter cloacae and isolate 8 from MWW as Paenibacillus silagei. These bacteria have important industrial and plant biotechnology applications.