A new single-cell protein from Clostridium autoethanogenum as a functional protein for largemouth bass (Micropterus salmoides)

Shifeng Ma; Xiaofang Liang; Pei Chen; Jie Wang; Xu Gu; Yuchang Qin; Christophe Blecker; Min Xue

doi:10.1016/j.aninu.2022.04.005

A new single-cell protein from Clostridium autoethanogenum as a functional protein for largemouth bass (Micropterus salmoides)

Anim Nutr. 2022 Apr 21:10:99-110. doi: 10.1016/j.aninu.2022.04.005. eCollection 2022 Sep.

Authors

Shifeng Ma^{1

2}, Xiaofang Liang¹, Pei Chen¹, Jie Wang¹, Xu Gu¹, Yuchang Qin³, Christophe Blecker², Min Xue¹

Affiliations

¹ National Aquafeed Safety Assessment Center, Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
² Food Science and Formulation, University of Liège, Gembloux Agro-Bio Tech, Avenue de la Faculté d' Agronomie, 2B, B-5030, Gembloux, Belgium.
³ Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.

Abstract

Clostridium autoethanogenum protein (CAP) is a new single-cell protein source originating from inactivated bacteria. An in vitro digestion experiment and an 8-wk growth experiment were conducted to evaluate the molecular weight distribution of the CAP hydrolysate, and the effects of dietary CAP levels on the growth performance, plasma parameters, hepatic and intestinal health, and the diversity of gut-adherent microbiota of largemouth bass (Micropterus salmoides). The fish (initial body weight of 47.99 ± 0.01 g) were fed diets where CAP gradually replaced 0% (CAP0), 12.5% (CAP12.5), 25% (CAP25), 37.5% (CAP37.5) and 50% (CAP50) of low-temperature steam dried anchovy fish meal (LTFM) in the diet. Results showed that the content of peptides below 1,000 Da in the CAP hydrolysate (0.56 mg/mL) was higher than that of the LTFM hydrolysate (0.48 mg/mL). Dietary CAP inclusion had no negative effect on growth performance, while whole-body lipid content significantly reduced in the CAP25 and CAP50 groups (P < 0.05). The plasma alanine aminotransferase activities and triglyceride concentrations in the CAP inclusion groups were significantly lower than those in the CAP0 group (P < 0.05). The plasma aspartate aminotransferase activity was significantly reduced in the CAP37.5 group (P < 0.05). The richness and diversity of the gut-adhesive microbiota and the proportion of Clostridium sensu stricto 12 in the CAP50 group were significantly higher than those in the CAP0 group (P < 0.05). Dietary CAP inclusion inhibited inflammatory responses by down-regulating the mRNA levels of interleukin 1β (IL1β), IL10 and transforming growth factor β1 (P < 0.05) in the liver. The mRNA levels of acetyl-CoA carboxylase 1 were significantly down-regulated in the CAP12.5, CAP25 and CAP37.5 groups (P < 0.05), while that of fatty acid synthase was significantly down-regulated in the CAP50 group (P < 0.05). These results demonstrate that dietary CAP inclusion could improve the hepatic and intestinal health of largemouth bass, and can be helpful to further develop CAP as a functional feed ingredient.

Keywords: Clostridium autoethanogenum protein; Growth; Gut-adherent microbiota; Hepatic and intestinal health; Lipid metabolism; Micropterus salmoides.