Dysbiosis of Gut Microbiota and Lipidomics of Content Induced by Dietary Methionine Restriction in Rice Field Eel (Monopterus albus)

Abstract

An 8-week feeding trial was conducted using the rice field eel (Monopterus albus) with six isonitrogenous and isoenergetic experimental diets of basic feed supplemented with different levels of methionine (0, 2, 4, 6, 8, or 10 g/kg). This study built upon previous research findings that showed dietary methionine restriction (M0, 0 g/kg) inhibited hepatic fatty acid metabolism and intestinal fatty acid transportation, but both are improved by dietary supplementation with a suitable level of methionine (M8, 8 g/kg). Hence, M0 and M8 were selected to investigate how methionine regulates the gut microbiota and lipidomics of M. albus. Compared with M0, values for gut bacterial Sobs, Shannon, ACE, and Chao1 indices of M8 were remarkably increased (p < 0.05), with Fusobacteria, Firmicutes, and Proteobacteria the dominant phyla and Cetobacterium, Plesiomonas, and Bacillus the main genera in the community under the M0 vs. M8 treatments. However, compared with M0, the proportion of phyla consisting of Fusobacteria decreased in M8, as did the Cetobacterium and Lactococcus at the genus level; conversely, the proportions corresponding to Firmicutes, Proteobacteria, and Chioroflexi phyla increased in M8, as did the Clostridium and Streptococcus genera. Many edges appeared in the circus and networks, demonstrating the interspecies interactions among different operational taxonomic units (OTUs). In addition, various OTUs within the same phylum were clustered within one module. Cooperative interactions were predominant in the two networks, while competitive interactions were prevalent in their submodules. Gut microbiota mainly played roles in nutrition (lipid, amino acid, and carbohydrate) transport and metabolism under the M0 vs. M8 treatments. The PLS-DA scores indicated a significant difference in the main lipidomic components between the M0 and M8 treatment groups. Namely, the TG(26:0/16:0/17:0), TG(28:0/16:0/16:0), TG(26:0/16:0/16:0), and TG(30:0/16:0/16:0)—among others—comprising the gut content were reduced under the M8 treatment (p < 0.001). The genus Clostridium was positively correlated with TG(18:1/18:1/22:5), TG(16:0/17:0/18:1), TG(18:0/18:1/20:3), and other compounds, yet negatively correlated with TG(18:0/17:0/20:0), TG(16:0/17:0/24:0), and TG(16:0/16:0/24:0), among others as well. According to the lipidomics analysis, the predicted KEGG pathways mainly included lipid and glycan biosynthesis and metabolism, and digestive, sensory, and immune systems. In conclusion, methionine restriction disturbed the microbial community balance and induced microbial dysfunctions, whereas methionine supplementation improved the homeostasis of gut microbiota and lipid metabolism of the rice eel.

Exploring the modulatory effects of brown seaweed meal and extracts on intestinal microbiota and morphology of broiler chickens challenged with heat stress

“…The metabolism of methionine through the transmethylation pathway generates S-adenosylmethionine, which is important for the methylation of lipids, and proteins ( Dash et al, 2016 ). Hu et al (2022) found that methionine restriction altered the microbial community balance and functions, while methionine supplementation enhanced the stability of gut microbiota and lipid metabolism of fish. According to Lee et al (2021) , heat-stressed chicks fed with L-Methionine had reduced intestinal blood vessel formation and maintained normal glucose and lipid metabolism.…”

“…Seaweed extract at 2 ml/L inclusion increased the pathway of gluconeogenesis, TCA and peptidoglycan among heat-stressed birds in our study. Metabolic pathways such as gluconeogenesis and TCA have inhibition potential against pathogenic bacteria ( Hu et al, 2022 ). Enhanced biosynthesis of peptidoglycan may increase the abundance of lactic acid bacteria populations in the gut, partially facilitating the growth benefits.…”

Broad bean (Vicia faba L.) caused abnormal lipid metabolism in grass carp (Ctenopharyngodon idellus) liver: Insight from the gut microbiota–liver axis

“…Although broad bean is rich in a wide range of nutrients, the amino acid composition of broad bean is unbalanced, especially lacking in methionine (Meng et al, 2021). Methionine is one of the essential amino acids for aquatic animals, and its deficiency caused intestinal flora disorders and liver fat accumulation (Hu et al, 2022;Yang et al, 2024). We also observed this phenomenon in the livers of grass carp fed a single broad bean diet, suggesting that methionine deficiency in broad bean may be one of the key factors causing liver steatosis in grass carp.…”

Characterization and Dynamics of the Gut Microbiota in Rice Fishes at Different Developmental Stages in Rice-Fish Coculture Systems

“…The rice-fish system (RFS), a "globally important agricultural heritage system" [1], is an integrated agri-aquaculture system (IAAS) that combines rice cultivation with aquaculture [2,3]. Compared to rice monoculture, a wide range of aquatic species (i.e., fish, carp, crabs, eel, and softshell turtles) are used in the RFS [4,5]. Rice and various animal species raised in the same system influence each other to balance the role of the rice-field ecosystem [6,7].…”

“…Most studies on rice-fish systems have focused on the ecology of aquatic animals [15][16][17], biodiversity conservation [1,5,18], and economic value [3,9]. In addition, an increasing number of studies on the gut microbial community of aquaculture animals raised in the RFS have been conducted using both DGGE technology and 16S rRNA sequencing, such as in the rice field eel (Monopterus albus) [4,19], carp [13,20], loach [21], and yellow catfish [22].…”