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Improvement in the growth performance of white shrimp, Litopenaeus vannamei , by a protease‐producing probiotic, Bacillus subtilis E20, from natto
Author(s) -
Liu C.H.,
Chiu C.S.,
Ho P.L.,
Wang S.W.
Publication year - 2009
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2009.04284.x
Subject(s) - shrimp , litopenaeus , bacillus subtilis , probiotic , biology , protease , penaeidae , food science , bacillales , microbiology and biotechnology , fermentation , bacteria , decapoda , fishery , biochemistry , enzyme , crustacean , genetics
Aims: To isolate and identify a benefic bacterium, Bacillus subtilis E20, from natto (fermented soybeans), and incorporate it into shrimp feed to promote shrimp growth performance. Methods and Results: A protease‐producing bacterium, E20, isolated from natto was identified as B. subtilis by an API 50 CHB kit and the 16S rDNA sequence. B. subtilis E20 was able to grow at a broad range of temperatures (10–50°C), pH values (5–10), and NaCl levels (0–9%). The best culture conditions for B. subtilis E20 to produce the protease were 40°C, a pH of 6–8 and 0% NaCl. No shrimp died after being injected with B. subtilis E20 [up to 10 9 colony‐forming units (CFU) per shrimp]. Bacillus subtilis E20 was incorporated in diets at the levels of 0 (control), 10 6 , 10 7 , and 10 8 CFU kg −1 for shrimp grow‐out culture, and results showed that after feeding on B. subtilis E20‐containing diets (10 8 CFU kg −1 of diet), shrimp had excellent growth performance and production compared to the control because protease activities in the digestive tract were improved by B. subtilis E20. Conclusions: Bacillus subtilis E20 isolated from natto is a great protease producer and is able to improve shrimp growth performance through increasing the digestibility of food. Significance and Impact of the Study: Results suggest that B. subtilis E20 is a potential candidate for use as a probiotic to improve shrimp growth performance, and consequently reduce feed costs.