Probiotic elimination of Micrococcus sp.

A review of: Dahiya, T., Gahlawat, S.K & Sihag, R. C. (2012). Elimination of Pathogenic
Bacterium (Micrococcus sp.) by the Use of Probiotics. Turkish Journal of Fisheries and Aquatic Sciences. 12 (1), 185-187.

The use of beneficial or probiotic bacteria has developed into an important research theme influencing a variety of ecological, medicinal and industrial practices of notable economic significance. Probiotic organisms are suggested to be able to disrupt inter-population relationships by releasing chemical substances which have a bactericidal or bacteriostatic effect upon other microbial populations. By manufacturing inhibitory substances, probiotic microorganisms can prevent the proliferation of opportunistic pathogens offering an alternative method to using antibiotics in regulating a microbial environment. Non-pathogenic strains of bacteria have been successfully applied in aquaculture to control fish diseases which can detrimentally affect stock levels and productivity by acting in the mucus of the intestinal tract of organisms and its environmental surroundings.

The objective of the study was to investigate the elimination of the pathogenic bacterium Micrococcus sp. using three probiotics. Indian magur catfish (Clarius batrachus L.) individuals were inoculated with Micrococcus sp. and the level of inhibition of each probiotic was assessed in both in vivo and in vitro studies over a five week period. Probiotic 1 contained a single bacterium Lactobacillus sporogenes and Probiotic 2 contained a single fungal yeast Saccharomyces bouardii. Probiotic 3 contained numerous bacteria of various origins; Nitromonas, Rhodococcus, Bacilus megaterium, Lecheni formis, Desulphovibrio Rhodococcus, Bacilus megaterium, Lecheni formis, Desulphovibrio sulphuricum, Psuedomonas, Chromatium, Chlorobium, Thiobacillus, Thioxidants, Thiobacilus ferroxidant, Methylomonas methyanica, Glucon acetobactor, Azospirillum, Trichoderma, Shizophyllum commune and Sclertium gluconicum.

The investigation confirmed the elimination of Micrococcus sp. during both in vivo and in vitro analysis. In vitro evaluation noted differences between each probiotic with a greater zone of inhibition in probiotic 1 when compared to probiotic 3 and probiotic 2. Consequently it was concluded that probiotic 1 showed the largest eliminating effect on Micrococcus sp., followed by probiotic 3 and probiotic 2 in a descending order of effectiveness. During in vivo assessment high levels of Micrococcus sp. were observed in individuals not treated by any of the three probiotics, leading to significant mortality rates of C. batrachus L. after 5 weeks. In contrast, individuals inoculated with any of the three probiotics showed a pattern of decline in viable counts of Micrococcus sp. The effectiveness of each probiotic was observed to exhibit the same pattern as identified during in vitro analysis (Probiotic 1 > Probiotic 3 > Probiotic 2).

The study demonstrates the significant potential associated with the application of probiotics in aquaculture, as comparable results have been observed in other studies evaluating different pathogenic bacteria using different fish species and probiotics. By effectively eliminating Micrococcus sp., the results suggest that all three probiotics could be valuable treatments in regulating population numbers of the bacterium, which has been linked with a range of infections holding influence in both the aquaculture and human health industries. Nevertheless, despite strong evidence for their effect upon the pathogen, further investigation remains necessary to fully understand the differences which characterise the function and potential application of each probiotic. Overall, the study was simple, concise and effective in achieving its objective; however the paper was beset by several inconsistencies in the presented information and numerous grammatical errors which made the content difficult to follow and understand
in places.