Effect of fed dietary yeast (Rhodotorula paludigena CM33) on shrimp growth, gene expression, intestinal microbial, disease resistance, and meat composition of Litopenaeus vannamei.

Yeast is a health-promoting and bio-therapeutic probiotic that is commonly used in aquaculture. Rhodotorula paludigena CM33 can accumulate amounts of intracellular carotenoids and lipid, which are regarded as nutritionally beneficial compounds in various aspects. The aim of this study was to evaluate the impact of different levels of R. paludigena CM33 (RD) incorporated in a dietary composition at 0% (control), 1% (1% RD), 2% (2% RD), and 5% (5% RD) on the growth of shrimp (Litopenaeus vannamei), their immune-related gene expression, intestinal health, resistance to Vibrio parahaemolyticus (VPAHPND) infection, and meat composition. The results showed significant improvements in the specific growth rate, weight gain, and survival of shrimp fed with 1% RD, 2% RD, and 5% RD, which were higher than the control group after 4 weeks of administration. The administration of 5% RD group resulted in a decrease in cumulative mortality upon VPAHPND challenge when compared to the control group. Furthermore, the expression levels of immune-responsive genes, including proPO system (prophenoloxidase-2: PO2), antioxidant enzyme (superoxide dismutase: SOD, glutathione peroxidase: GPX, and catalase: CAT), JAK/STAT pathway (signal transducer and activator of transcription: STAT, gamma interferon inducible lysosomal thiol reductase: GILT), IMD pathway (inhibitor of nuclear factor kappa-B kinase subunit beta and epsilon: IKKb and IKKe), and Toll pathway (Lysozyme) genes, were up-regulated in the 5% RD group. In the context of microbiota, microbiome analysis revealed that the main phyla in shrimp intestines were Proteobacteria, Firmicutes, Bacteroidota, Campilobacterota, Actinobacteriota, and Verrucomicrobiota. At the genus level, Vibrio was found to be reduced in the 5% RD group, whereas the abundance of potentially beneficial bacteria Bifidobacterium was increased. The 5% RD group showed a significant increase in the levels of crude protein and crude lipid, both of which are essential nutritious components. Our results show the capability of R. paludigena CM33 as a probiotic supplement in shrimp feed in improving growth, antimicrobial responses against VPAHPND, and meat quality by increasing protein and lipid content in shrimp.

Sriphuttha C ，Limkul S ，Pongsetkul J ，Phiwthong T ，Massu A ，Sumniangyen N ，Boontawan P ，Ketudat-Cairns M ，Boontawan A ，Boonchuen P ... -  《-》

A comparative study on effects of dietary three strains of lactic acid bacteria on the growth performance, immune responses, disease resistance and intestinal microbiota of Pacific white shrimp, Penaeus vannamei.

The present study evaluated the growth performance, immune responses, disease resistance and intestinal microbiota in Penaeus vannamei fed diets supplemented with three strains of lactic acid bacteria (LAB). The basal diet (control, CO) supplemented with Lactobacillus plantarum W2 (LA), Pediococcus acidilactici Nj (PE), Enterococcus faecium LYB (EN) and florfenicol (FL), respectively, formed three LAB diets (1 × 1010 cfu kg-1) and a florfenicol diet (15 mg kg-1, positive control), were fed to shrimp for 42 days. Results indicated that specific growth rate, feed efficiency rate, and disease resistance of shrimp against Vibrio parahaemolyticus in the treatment groups were significantly improved versus the control (P < 0.05). Compared with the control, acid phosphatase, alkaline phosphatase, phenonoloxidase, total nitric oxide synthase, peroxidase, superoxide dismutase activities, total antioxidant capacity, and lysozyme content in the serum and the relative expression levels of SOD, LZM, proPO, LGBP, HSP70, Imd, Toll, Relish, TOR, 4E-BP, eIF4E1α and eIF4E2 genes in the hepatopancreas of LAB groups were enhanced to various extents. Intestinal microbiota analysis showed that the LA and EN groups significantly improved microbial diversity and richness, and LAB groups significantly altered intestinal microbial structure of shrimp. At the phylum level, the Verrucomicrobiota in the LA and PE groups, the Firmicutes in the EN group, and the Actinobacteriota in the PE and EN groups were enriched. Moreover, the CO group increased the proportion of potential pathogens (Vibrionaceae and Flavobacteriaceae). The potential pathogen (Vibrio) was reduced, and potential beneficial bacteria (Tenacibaculum, Ruegeria and Bdellovibrio) were enriched in response to dietary three strains of LAB. When the intestinal microbiota homeostasis of shrimp is considered, L. plantarum and E. faecium showed better effects than P. acidilactici. However, due to the concerns on the possible potential risks of E. faecium strains to human health, L. plantarum W2 is more suitable for application in aquaculture than E. faecium LYB. Considering collectively the above, Lactobacillus plantarum W2 could be applied as better probiotic to improve the growth performance, non-specific immunity, disease resistance and promote intestinal health of P. vannamei.

Luo K ，Liu Y ，Qin G ，Wang S ，Wei C ，Pan M ，Guo Z ，Liu Q ，Tian X ... -  《-》

Dietary SYNSEA probiotic improves the growth of white shrimp, Litopenaeus vannamei and reduces the risk of Vibrio infection via improving immunity and intestinal microbiota of shrimp.

The growth performance, immunological status, and intestinal microbiology of white shrimp, Litopenaeus vannamei, were evaluated after dietary administration of the commercial probiotic SYNSEA. Shrimp were fed a control diet (without probiotic supplement) and two levels of SYNSEA probiotic, a low concentration of SYNSEA (LSL) containing 105 CFU (g diet)-1Bacillus subtilis and 105 CFU (g diet)-1 lactic acid bacteria (LAB), and a high concentration of SYNSEA (LSH) containing 106 CFU (g diet)-1B. subtilis and 106 CFU (g diet)-1 LAB, for 12 weeks. Shrimp fed with the LSL diet significantly increased growth performance as well as final weight and feed efficiency compared to the control, but not the LSH diet. After being orally challenged with Vibrio parahaemolyticus, shrimp fed with LSL diet prior to the challenge or fed with LSL and pathogen simultaneously showed significantly lower mortality compared to the control. SYNSEA probiotic significantly improved shrimp immune response, including lysozyme activity in LSL and LSH groups, and phagocytic activity in the LSL group in comparison to the control. In addition, the gene expressions of anti-lipopolysaccharide factor 2 in LSL and LSH groups, and penaeidin 4 in LSL were also up-regulated. Although there was no significant difference among groups for hepatopancreas and intestinal morphology, the muscular layer thickness and villi height were slightly improved in the intestines of shrimp fed SYNSEA. The 16S rDNA gene amplicon sequence analysis using next-generation sequencing revealed a significant decrease in α-diversity (Margalef's species richness) after oral administration of SYNSEA due to an increase in the relative abundance of beneficial bacteria in the gut flora of shrimp, such as Lactobacillus, Shewanella, and Bradymonadales and a decrease in harmful bacteria, such as Vibrio, Candidatus_Berkiella, and Acinetobacter baumannii. Together the data suggest that the provision of SYNSEA probiotic at 105 CFU (g diet)-1B. subtilis and 105 CFU (g diet)-1 LAB can improve shrimp growth, enhance immunity, and disease resistance status of the host. In addition, these findings conclude that SYNSEA probiotic has great preventive and therapeutic potential for Vibrio infection in shrimp aquaculture.

Lee JW ，Chiu ST ，Wang ST ，Liao YC ，Chang HT ，Ballantyne R ，Lin JS ，Liu CH ... -  《-》

Dietary supplementation of probiotic Bacillus coagulans ATCC 7050, improves the growth performance, intestinal morphology, microflora, immune response, and disease confrontation of Pacific white shrimp, Litopenaeus vannamei.

The present study assessed the effects of probiotic bacterium Bacillus coagulans ATCC 7050 (BC) fed at different inclusion levels (0 (BO), 1 × 106 (BC1), 1 × 107 (BC2) and 1 × 108 (BC3) CFU g-1 feed) on growth, feed utilization, body composition, intestinal morphology, microflora, immune response, and resistance to Vibrio parahaemolyticus infection in Litopenaeus vannamei. After 56 days of the feeding trial, the survival rate ranged from 83.33 to 94.17% with no significant difference between dietary treatments (P > 0.05). Dietary probiotic supplementation also affected the intestinal microflora composition. At the phylum level, Proteobacteria accounted for the majority of bacteria followed by Bacteroidetes irrespective of the group. At the genus level, the abundance of opportunistic pathogenic bacteria, such as Vibrio, Tenacibaculum, and Photobacterium significantly decreased (P < 0.05) with an increasing probiotic concentration, and BC3 group experiencing the least. Additionally, increasing probiotic inclusion in diet downregulated the abundance of Muricauda, Kangiella, and Shewanella in shrimps, with the least, observed in the BC3 group. However, beneficial bacteria Pseudoalteromonas significantly increased (P < 0.05) in the intestines of shrimp fed BC3 diet (P < 0.05) compared to other groups including the control. Compared to the control, a significant increase (P < 0.05) of the probiotic treated groups in the final weight, weight gain rate (WGR), specific growth rate (SGR), condition factor (K), activity of lysozyme (LYZ), acid phosphatase (ACP), superoxide dismutase (SOD), total protein (TP), albumin (ALB) in serum, glutathione peroxidase (GSH-Px) in serum and liver, and a significant decrease (P < 0.05) in feed conversion ratio (FCR), triglyceride (TG) in serum, and Malondialdehyde (MDA) in serum and liver were achieved. Increasing probiotic treatment again improved the digestive ability, thus; a significant increase in the activities of lipase, amylase, trypsin, and an enhancement in the villus height, villus width, and muscle thickness of the intestines of the shrimps which correspondingly alleviated intestinal injury. Furthermore, the supplementation of probiotics in challenge test significantly (P < 0.05) enhanced the resistance of shrimp against V. parahaemolyticus infection recording BC3 to receive the highest relative percentage survival (RPS) value of 76%. In conclusion, higher inclusion levels of probiotic BC at 1 × 108 CFU g-1 feed (BC3) in diets can be considered to enhance the growth, intestinal morphology and microflora, immune response and resistance to Vibrio parahaemolyticus of L. vannamei.

Amoah K ，Huang QC ，Tan BP ，Zhang S ，Chi SY ，Yang QH ，Liu HY ，Dong XH ... -  《-》

Two host gut-derived lactic acid bacteria activate the proPO system and increase resistance to an AHPND-causing strain of Vibrio parahaemolyticus in the shrimp Litopenaeus vannamei.

Lactic acid bacteria (LAB) are group of beneficial bacteria that have been proposed as relevant probiotics with immunomodulatory functions. In this study, we initially isolated and identified host-derived LAB from the gut of the Pacific white shrimp Litopenaeus vannamei. Analysis of the bacterial 16S rRNA gene sequence revealed two candidate LAB, the Lactobacillus plantarum strain SGLAB01 and the Lactococcus lactis strain SGLAB02, which exhibited 99% identity to the L. plantarum strain LB1-2 and the L. lactis strain R-53658, which were isolated from bee gut, respectively. The two LAB displayed antimicrobial activities against gram-positive and gram-negative bacteria, including the virulent acute hepatopancreatic necrosis disease (AHPND)-causing strain of Vibrio parahaemolyticus (VPAHPND). Viable colony count and SEM analysis showed that the two candidate LAB, administered via oral route as feed supplement, could reside and adhere in the shrimp gut. Double-stranded RNA-mediated gene silencing of LvproPO1 and LvproPO2 revealed a significant role of two LvproPOs in the proPO system as well as in the immune response against VPAHPND infection in L. vannamei shrimp. The effect of LAB supplementation on modulation of the shrimp proPO system was investigated in vivo, and the results showed that administration of the two candidate LAB significantly increased hemolymph PO activity, the relative mRNA expression of LvproPO1 and LvproPO2, and resistance to VPAHPND infection. These findings suggest that administration of L. plantarum and L. lactis could modulate the immune system and increase shrimp resistance to VPAHPND infection presumably via upregulation of the two LvproPO transcripts.

Chomwong S ，Charoensapsri W ，Amparyup P ，Tassanakajon A ... -  《-》