CHARACTERIZATION AND NUMERICAL-ANALYSIS OF THE MICROBIAL COMMUNITY INRAW BAKERS-YEAST FACTORY EFFLUENT

Microbial counts on 3 different batches from the balancing tank sedime nt, as well as from the concentrated and general effluents from a bake r's yeast factory were determined on 3 media under aerobic, facultativ e and anaerobic conditions. Then microbial enumeration data varied con siderably (4.2 x 10(3) to 2.1 x 10(8) cfu/ml), with the aerobic counts on the ''richer'' media generally being higher. A total of 326 microb ial strains were isolated, of which 28 isolates were yeast strains. Th e prevalent strains isolated under aerobic conditions were identified as Pseudomonas paucimobilis, Acinetobacter lwoffii and Bacillus lichen iformis. The majority of strains isolated under facultative anaerobic conditions were identified as Acinetobacter lwoffii, Pseudomonas pauci mobilis and Citrobacter freundii. The prevalent anaerobic bacterial co mmunity consisted mainly of Lactobacillus acidophilus, Clostridium bei jerinckii and Eubacterium limosum. The overall similarity of the isola tes, based on 74 phenotypic characters, was determined using the Sokal and Michener coefficient. The prevalent bacteria clustered prominentl y within a few large clusters. The wide distribution and variety of ba cteria isolated, reflected the complexity of the raw baker's yeast eff luent ecosystem. It is, however, clear that baker's yeast effluent can not be ignored as a source of bacterial contamination with potential h ealth implications.