Identification and methods for prevention of <i>Enterococcus mundtii</i> infection in silkworm larvae, <i>Bombyx mori</i>, reared on artificial diet
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- Nwibo Don Daniel
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo
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- Matsumoto Yasuhiko
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo
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- Sekimizu Kazuhisa
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo Genome Pharmaceuticals Institute
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抄録
Previously, it was reported that Enterococcus mundtii (E. mundtii) was associated with flacherie disease of silkworm larvae reared on artificial diet. In this study, we report that E. mundtii was isolated from diseased silkworm larvae, and validated as a pathogenic bacterium of the animal. When silkworm larva was infected with 1.04 × 106 colony-forming units of E. mundtii via oral administration of diet, half population died within six days, indicating that the bacterium is pathogenic to silkworm. Less severe infection was found to cause anorexia and hamper the development of larvae. This pathogen was found to proliferate in both time- and dose-dependent manner in the gastrointestinal tract of the animal. The bacterium was isolated from powder of artificial diet made from mulberry leaves, and from mulberry leaves growing at a field. Minimum inhibitory concentration determination revealed that this bacterium was susceptible to tested antibiotics. Vancomycin treatment of diet significantly decreased the number of E. mundtii in intestine of silkworm larvae infected with the bacteria, compared to control. Furthermore, autoclaving or gamma ray irradiation of diet was also effective for exclusion of E. mundtii from the diet without the loss of its nutrient capacities. These results suggest that mulberry leaves used in making artificial diet for silkworm larvae is one of the sources of E. mundtii infection; and that antibiotic treatment, autoclaving or gamma ray irradiation of artificial diet can exclude the bacteria.
収録刊行物
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- Drug Discoveries & Therapeutics
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Drug Discoveries & Therapeutics 9 (3), 184-190, 2015
特定非営利活動法人 バイオ＆ソーシャル・サイエンス推進国際研究交流会