High replacement of fishmeal by Chlorella meal affects intestinal microbiota and the potential metabolic function in largemouth bass (Micropterus salmoides)

Abstract

Microalgae have beneficial effects on the performance of fish as additives and they are becoming a promising alternative to fishmeal as macronutrient ingredients. However, the impact on the fish intestinal microbiome and the function, caused by microalgae as protein sources in diets, remains unclear. This study aimed to determine the composition and potential function of the intestinal microbial community of largemouth bass (Micropterus salmoides) fed diets at five replacement levels (0, 25, 50, 75 and 100%) of fishmeal by Chlorella meal in a basal diet (400 g kg−1) after 8 weeks. The results showed significant decreases in unique amplicon sequence variants in the intestine at the higher levels of fishmeal replacement. At 50% of fishmeal replacement, dietary inclusions of Chlorella meal had no impact on species richness and Shannon diversity and the community structure of the intestinal microbiota. However, high levels of fishmeal replacement (75 and 100%) significantly induced intestinal community disturbance and diversity loss in largemouth bass. Responding to the high fishmeal replacement level, the dominant genus Cetobacterium and Pleslomonas sharply increased and several taxa from Lactobacillus decreased significantly. Functional data predicted by PICRUSt revealed that nutrition-related metabolism was dominant in the intestinal microbiota of fish fed all the five diets, although some potential functions, particularly amino acid and lipid metabolisms, and energy metabolism, were upregulated firstly, and then downregulated in fish fed diets with the increase of dietary Chlorella meal. Meanwhile, certain pathways were not enriched in intestinal microbiome until up to 75% of fishmeal replacement, such as carbohydrate metabolism, and cofactors and vitamins metabolism. To conclude, this study reveals that fishmeal replacement (50%) by Chlorella meal at the level of 237 g kg−1 in diets is feasible for largemouth bass without impairing the microbiome structure and the metabolism function, providing an alternative strategy for evaluating the possibility of fishmeal replacement by microalgae in aquafeeds.

Dietary Effects of a Short-Term Administration of Microalgae Blend on Growth Performance, Tissue Fatty Acids, and Predominant Intestinal Microbiota in Sparus aurata

“…Studies considering the influence of dietary microalgae on fish intestinal microbial communities reported confounding results. According to Zhang et al [ 59 ], dietary Chlorella meal did not affect microbial diversity and richness species of largemouth bass ( Micropterus salmoides ) when the level of fishmeal replacement was less than 50%. In contrast, higher replacement levels resulted in a remarkable diversity loss, indicating different gut microbes’ responses to dietary inclusion levels.…”

Alternative proteins as fish meal substitution in diets for largemouth bass (Micropterus salmoides): a mini review

“…As one of the commercial SCP, FeedKind ® is produced by methanotroph with methane gas as the single carbon source (Sharif et al., 2021). Recently, Zhang and his team informed that 129 g kg −1 FeedKind ® can substitute 150 g kg −1 FM (33% FM was substituted by FeedKind ® ) without adverse effects on the growth performance, while replacing 100 g kg −1 FM with 86 g kg −1 FeedKind ® (22% FM was substituted by FeedKind ® ) was more beneficial to intestinal health of LMB (IBW: 5.12 ± 0.03 g; Zhang et al., 2022d). Fei et al .…”

“…Algae have also been recognised as a SCP in aquatic feeds, which contain balanced amino acid composition, high polyunsaturated fatty acid, and display good palatability, thus exhibit less negative effects on the growth performance of aquatic animals (Sagaram et al., 2021; Ahmad et al., 2022). The most studied algae protein for LMB is Chlorella meal (Xi et al., 2022; Zhang et al., 2022d). For example, Chlorella meal could replace 50% at the level of 237 g kg −1 in diets for LMB (IBW: 17.64 ± 0.03 g) without impairing the microbial community structure and the metabolism function (Zhang et al., 2022d).…”

Multi-omics approach to study the dual effects of novel proteins on the intestinal health of juvenile largemouth bass (Micropterus salmoides) under an alternate feeding strategy

“…The recent research discovered very favorable associations between SCFAs and Shannon/Simpson. These indicators were used to assess the intestinal health (9,43,44) in earlier investigations. In addition, our findings were confirmed by a study conducted on mice, which indicated that increasing a-diversity linked to higher levels of short-chain fatty acids (45).…”

“…Earlier studies have examined the impacts of these proteins on Cyprinus carpio var. specularis, Litopenaeus vannamei, and Micropterus salmoides (4,(7)(8)(9). Nonetheless, these studied mainly focus on partial substitution strategy of fishmeal, and explore their functions on muscle quality, growth performance and intestinal health.…”