The present study was undertaken to investigate the prevalence of some selected heterotrophic bacteria in one of the sewage lagoons and in the river Buriganga, which receives the sewage effluents from the sewage lagoons, with a view to evaluate the effect of sewage treatment. The heterotrophic plate count (HPC) ranged from 1.1 x 10 8 to 3.0 x 10 9 cfu/ml in sewage lagoon from January to December 2005. The HPC values ranged from 1.1 x 10 5 to 3.0 x 10 9 cfu/ml in the outfall of the sewage effluents and other sampling locations in the river Buriganga. The total and faecal coliform counts of the sewage lagoon and the discharge point in the river were always very high as >2.4 x 10 3 cfu/100 ml in all seasons as measured by the MPN method. Salmonellae were isolated occasionally, while vibrios were frequently isolated from all the sampling points from throughout the year. The MPN values of nitrifying bacteria were also estimated to compare with HPC values. Ammonium oxidizers ranged from 1.1 x 10 2 to 1.1 x 10 3 /ml in the sewage lagoon and 2.0 x 10 1 to 2.2 x 10 3 /ml in the river water. Nitrite oxidizers showed very low MPN values. This study suggests that the water of the river Buriganga was heavily polluted. It also suggests that the oxidation or self-purification system in the oxidation lagoons and subsequent treatment of the effluents were far from satisfactory level. Even the discharged sewage in the river Buriganga remains equally contaminated, which had been demonstrated by the presence of large number of pathogenic organisms. This poses health hazards to the users of the water from the river and also poses risks for the aquatic organisms of this water body.
Total load of bacteria, fungi and pathogenic microorganisms in muscle-and-skin samples of 12 different species of fish were analyzed. Highest standard plate count (5.1 x 106 cfu/g) was observed in Batashi (Clupisoma atherinoides) and lowest (2.3 x 105 cfu/g) in Rui (Labeo rohita). Total bacterial load was almost similar in case of other fishes. Mold count was highest (7.5 x 102 cfu/g) in shrimp (Penaeus indicus) and lowest (8.0 x 101 cfu/g) in Pabda (Ompok pabda). Yeast count varied between 1.0 x 103 cfu/g in Batashi and 7.0 x 101 cfu/g in Rui. Total coliform and faecal coliform were detected in all the fish samples. Coliform count measured by most probable number (MPN) method was found to be 240/g in all fish samples. Faecal coliform count in the fish samples varied from 2.8 to 240/g. Salmonella was detected in at least two-third of the samples analysed. High microbial load in raw fishes indicates that raw fish would decompose very quickly at ambient temperature, and the presence of coliforms and Salmonella indicates the raw fish handling is not safe.Keywords: Fish, Microbiological analysis, Pathogens Bangladesh J Microbiol, Volume 24, Number 1, June 2007, pp 67-69
With a view to get a pen picture about the trend and extent of quality changes and as well as shelf life of the head off and head on shrimp (Macrobrachium rosenbergii, De Man, 1879), the present study have been carried out . Quality changes have been measured by application of sensory score evaluation and changes in chemical indices such as Total Volatile Nitrogen (TVN) value, pH and level of moisture at different time interval and Total Bacterial Count (TBC) at 15 o C during the study period. The results of the sensory score evaluation indicates that the shrimp quality decreased to the limits of acceptability at 12th days of ice storage. The head off shrimp kept slight better than corresponding head on shrimps. The bacterial counts determined at 15 o C have been found to increase from 10 3 -10 7 and 10 4 -10 8 cfu/gm for head off and head on shrimp respectively at the limit of acceptability. The moisture level increased from initial 78.85gm% to final 83.80gm% (head off) & 79.0gm% to 84.0gm% (head on) and pH value increases from 7.1 to 8.1 during the whole period of iced preservation . Both head off and head on shrimp remained in acceptable condition for up to 12 and 14 days of storage respectively while the quality of fish deteriorates and become unacceptable. The bacterial count corresponding to unacceptable condition ranges from 10 8 -10 9 cfu/gm fish sample. The TVN value corresponding to rejection condition were 45-50mg N/100gm fish sample.
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