Isolation and characterization of bacteria from fermented cooked-rice

Abstract

Fermented rice is a traditional dish of Bangladesh and believed to contain various beneficial bacterial species. This study has been conducted to isolate and characterize bacteria from the samples of fermented rice. For this purpose, the samples were collected from three different districts of Bangladesh, namely Chapainawabganj, Rajshahi and Kushtia. A total of three bacterial isolates, denoted as Isolate 1, Isolate 2 and Isolate 3, were isolated from the fermented rice samples and identified by a series of morphological and biochemical tests. The three isolates were gram-positive, round-shaped and non-motile. For the biochemical characterization, the isolated bacteria were tested with several media like Mannitol Salt Agar, MacConkey Agar, EMB Agar, TSI Agar, Simmons Citrate Agar, Urea Agar, BSA and Starch Agar with Catalase assay. Thus the isolates have been confirmed as Staphylococcus sp. both morphologically and biochemically. The isolates were also tested for their antibiotic sensitivities by the disc diffusion method with twelve different antibiotics. All of the isolated bacteria showed resistance to three of the antibiotics, namely aztreonam, ampicillin and penicillin, and showed susceptibility to four, such as imipenem, ciprofloxacin, rifampicin and doxycycline. According to this study, it can be concluded that Staphylococcus sp. could be found in the fermented rice, and antibiotics are available to control these bacteria.