Comparison of the probiotic effects of freshwater and marine photosynthetic bacteria in kuruma shrimp (Marsupenaeus japonicus) culture

ABSTRACT

In a field study, the probiotic effects of a freshwater purple nonsulfur photosynthetic bacterium (PNSB), Rhodobacter sphaeroides, and a marine PNSB, Rhodovulum sulfidophilum, on kuruma shrimp (Marsupenaeus japonicus) were compared by using two commercially operating shrimp ponds. Shrimp were fed with feed containing 0.01% fresh weight (10⁶ cfu/g feed) of PNSB cells for 152 d. The marine PNSB showed a better performance than the freshwater PNSB in average body weight at harvest time, survival rate (P < 0.001 by Fisher’s exact test), and feed conversion rate. The effects of freshwater and marine PNSB on shrimp gene expression were also compared by next-generation sequencing and quantitative RT-PCR. Both freshwater and marine PNSB promoted the expression of several genes related to the innate immune system, including NADPH oxidase, superoxide dismutase, lysozyme, antimicrobial peptides, and lectins, and the promotive effect of marine PNSB was stronger than that of freshwater PNSB. The cost of PNSB was calculated to be US$ 0.003–0.005 per kg feed; thus, marine PNSB is a cost-effective and feasible probiotic for shrimp aquaculture.

KEYWORDS:

• Purple nonsulfur photosynthetic bacterium (PNSB)
• Rhodobacter sphaeroides
• Rhodovulum sulfidophilum
• Marsupenaeus japonicus
• probiotics
• next-generation sequencing

Acknowledgments

We thank the late Dr Hiro Takahashi of Graduate School of Medical Sciences, Kanazawa University, for his help in analyzing the NGS data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author Contributions

Aoi Koga performed the qRT-PCR experiments and analyzed the data. Shinsuke Takiguchi performed the RNA isolation experiment. Yusaku Tani and Ken-ichi Ozaki designed and performed the shrimp pond experiment. Takaaki Maki determined the condition of the preparation of shrimp feed containing PNSB. Hiroshi Okuhata and Satoshi Tanaka analyzed the transcriptome data. Shuhei Hayashi and Shinjiro Yamamoto partly performed the RNA experiment and edited the manuscript. Hitoshi Miyasaka designed the study and wrote the manuscript.

Supplementary material

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