Probiotics, Prebiotics, and Synbiotics Utilization in Crayfish Aquaculture and Factors Affecting Gut Microbiota

Effects of dietary supplementation with heat-killed Lactobacillus acidophilus on growth performance, digestive enzyme activity, antioxidant capacity, and inflammatory response of juvenile large yellow croaker (Larimichthys crocea)

A ten-week culture trial in juvenile large yellow croaker (Larimichthys crocea) (10.80 ± 0.10 g) was conducted to assess the impact of supplementing heat-killed Lactobacillus acidophilus (HLA) on growth performance, intestinal digestive enzyme activity, antioxidant capacity and inflammatory response. Five iso-nitrogenous (42 % crude protein) and iso-lipidic (12 % crude lipid) experimental feeds with different levels of HLA (0.0 %, 0.1 %, 0.2 %, 0.4 %, or 0.8 %) were prepared. They were named FO (control group), HLA0.1, HLA0.2, HLA0.4 and HLA0.8, respectively. The results indicated that HLA addition had no impact on survival (P > 0.05). In this experiment, the final body weight, weight gain rate and specific growth rate showed a quadratic regression trend, initially increasing and subsequently decreasing with the increasing in HLA levels, and attained the peak value at 0.2 % HLA supplemental level (P < 0.05). In contrast to the control group, in terms of digestive ability, amylase, lipase and trypsin exhibited a notable linear and quadratic pattern, demonstrating a substantial increase when 0.1% 0.2 % HLA was added in the diets (P < 0.05). Notably, elevated levels of catalase (CAT) activity, superoxide dismutase (SOD) activity, and total antioxidant capacity (T-AOC) were observed in the liver when adding 0.1%-0.2 % HLA, and the level of malondialdehyde (MDA) was significantly decreased and the liver exhibited a notable upregulation in the mRNA expression levels of nrf2, cat, sod2, and sod3 (P < 0.05). Additionally, the mRNA levels of genes associated with tight junctions in the intestines (zo-1, zo-2 and occludin) exhibited a significant upregulation when 0.2 % HLA was added in the feed (P < 0.05). Furthermore, the levels of mRNA expression for proinflammatory genes in the intestines including tnf-α, il-1β, il-6 and il-8 exhibited a quadratic regression trend, characterized by an initial decline followed by subsequent growth (P < 0.05). Meanwhile, the levels of mRNA expression for genes linked to anti-inflammatory responses in the intestines (including il-10, tgf-β, and arg1) exhibited a quadratic regression pattern, initially increasing and subsequently decreasing (P < 0.05). Compare with the control group, the levels of tnf-α, il-1β and il-8 expression were notably downregulated in all HLA addition groups (P < 0.05). When 0.2 % HLA was added, the expression levels of il-10, tgf-β and arg1 in the intestinal tract were markedly increased (P < 0.05). Overall, the supplementation of 0.2 % HLA in the feed has been shown to enhance the growth performance. The enhancement was attributed to HLA's capacity to improve antioxidant function, intestinal barrier integrity, and mitigate inflammatory responses. This research offers a scientific foundation for the utilization of HLA in aquaculture.

A comprehensive review on the utilization of probiotics in aquaculture towards sustainable shrimp farming

Probiotics in shrimp aquaculture have gained considerable attention as a potential solution to enhance production efficiency, disease management, and overall sustainability. Probiotics, beneficial microorganisms, have shown promising effects when administered to shrimp as dietary supplements or water additives. Their inclusion has been linked to improved gut health, nutrient absorption, and disease resistance in shrimp. Probiotics also play a crucial role in maintaining a balanced microbial community within the shrimp pond environment, enhancing water quality and reducing pathogen prevalence. This article briefly summarizes the many ways that probiotics are used in shrimp farming and the advantages that come with them. Despite the promising results, challenges such as strain selection, dosage optimization, and environmental conditions are carefully addressed for successful probiotic integration in shrimp aquaculture. The potential of probiotics as a sustainable and ecologically friendly method of promoting shrimp development and health while advancing environmentally friendly shrimp farming techniques is highlighted in this analysis. Further research is required to fully exploit probiotics' benefits and develop practical guidelines for their effective implementation in shrimp aquaculture.

Host-related traits influence the microbial diversity of the invasive signal crayfish Pacifastacus leniusculus

The microbiome influences a variety of host-environment interactions, and there is mounting evidence of its significant role in biological invasions. During invasion, shifts in microbial diversity and function can occur due to both changing characteristics of the novel environment and physiological condition of the host. The signal crayfish (Pacifastacus leniusculus) is one of the most successful crayfish invaders in Europe. During range expansion, its populations often exhibit differences in many traits along the invasion range, including sex-composition, size-structure and aggressiveness, but to date it was not studied whether crayfish traits can also drive changes in the host microbiome. Thus, we used 16S rRNA gene amplicon sequencing to examine the effects of host-related traits, namely total length (TL), body condition index (FCF), hepatosomatic index (HSI) and sex on the microbial diversity of the signal crayfish. We examined both external (exoskeletal) and internal (intestinal, hepatopancreatic, hemolymph) microbiomes of 110 signal crayfish individuals from four sites along its invasion range in the Korana River, Croatia. While sex did not exhibit a significant effect on the microbial diversity in any of the examined tissues, exoskeletal, intestinal and hemolymph microbial diversity significantly decreased with increasing crayfish size. Additionally, significant effects of signal crayfish condition (FCF, HSI) on microbial diversity were recorded in the hepatopancreas, a main energy storage organ in crayfish that supports reproduction and growth and also regulates immune response. Our findings provide a baseline for evaluating the contribution of microbiome to an invader's overall health, fitness and subsequent invasion success.