Abundance Of Vibrio Research Articles

Effects of Dietary Mannan Oligosaccharides on Non-Specific Immunity, Intestinal Health, and Antibiotic Resistance Genes in Pacific White Shrimp Litopenaeus vannamei.

This study was conducted to comprehensively investigate the beneficial effects of a mannan oligosaccharide product (hereinafter called MOS) on Litopenaeus vannamei and optimum level of MOS. Five isonitrogenous and isolipid diets were formulated by adding 0%, 0.02%, 0.04%, 0.08%, and 0.16% MOS in the basal diet. Each diet was randomly fed to one group with four replicates of shrimp in an 8-week feeding trial. The results showed that dietary MOS improved the growth performance and the ability of digestion of shrimp. Dietary MOS significantly increased the activity of total superoxide dismutase, catalase, and glutathione peroxidase and decreased the content of malondialdehyde in plasma of shrimp. Dietary MOS significantly increased the activity of alkaline phosphatase and lysozyme in plasma and the hemocyte counts. Dietary MOS significantly upregulated the expression of Toll, lysozyme, anti-lipopolysaccharide factor, Crustin, and heat shock protein 70 in the hepatopancreas. And dietary MOS significantly upregulated the expression of intestinal mucin-2, mucin-5B, and mucin-19, while it decreased the expression of intestinal mucin-1 and macrophage migration inhibitory factor. Dietary MOS improved the bacterial diversity; increased the abundance of Lactobacillus, Bifidobacterium, Blautia, and Pseudoalteromonas; and decreased the abundance of Vibrio in the intestine. Shrimp fed MOS diets showed lower mortality after being challenged by Vibrio parahaemolyticus. Notably, this study found a decrease in antibiotic resistance genes and mobile genetic elements after MOS supplementation for the first time. The present results showed that diet with MOS supplementation enhanced the organismal antioxidant capacity and immunity, improved intestinal immunity, optimized intestinal microecology, mitigated the degree of antibiotic resistance, and increased the resistance to V. parahaemolyticus in L. vannamei, especially when supplemented at 0.08% and 0.16%.

Process optimization for fermented siwu decoction by multi-index-response surface method and exploration of the effects of fermented siwu decoction on the growth, immune response and resistance to Vibrio harveyi of Pacific white shrimp (Litopenaeus vannamei)

The purpose of this study was to explore the optimal fermentation technology of Chinese herbal medicine formula-Siwu Decoction and the effects of fermented Siwu Decoction (FSW) on the growth performance, immune response, intestinal microflora and anti microbial ability of Litopenaeus vannamei. Response to surface methodology (RSM) was used to optimize the fermentation process of Siwu Decoction. The optimal fermentation conditions were obtained as follows: inoculation amount of mixed strains was 4.5%, fermentation time was 36 h, and the ratio of material to liquid was 20%. A total of 1260 shrimps were selected and divided into seven groups, three in parallel in each group. The dietary level of each group was as follows: Control （No additions）, USW1 (0.2% unfermented herbal medicine), USW2 (0.5% unfermented herbal medicine), USW3 (0.8% unfermented herbal medicine), FSW1 (0.2% fermented herbal medicine), FSW2 (0.5% fermented herbal medicine), FSW3 (0.8% fermented herbal medicine). The immune response and antioxidant defense ability of hemocytes and intestine were measured at 21 and 42 days of feeding and the intestinal flora and growth performance were measured at 42 days of feeding, after that, a 7-day challenge test against Vibrio harveyi was conducted. The results showed that fermented Siwu Decoction significantly improved the growth performance and body composition of Litopenaeus vannamei; significantly increased the total number of hemocytes, phagocytic activity, antibacterial activity and bacteriolytic activity of Litopenaeus vannamei, and improved the antioxidant activity of Litopenaeus vannamei; the addition of fermented Siwu Decoction significantly increased the gene expression level of hemocytes and intestinal tract of Litopenaeus vannamei, and improved the antioxidant activity of Litopenaeus vannamei. The abundance of Bacillus increased, while the abundance of Vibrio decreased. After Vibrio harveyi challenge, the cumulative mortality of FSW group was significantly lower than that of control group. Fermented Siwu Decoction may be a potential physiological enhancer in aquaculture, and can be widely used in aquaculture.

Environmental effects of nanoparticles on the ecological succession of gut microbiota across zebrafish development

The environmental stresses could significantly affect the structure and functions of microbial communities colonized in the gut ecosystem. However, little is known about how engineered nanoparticles (ENPs), which have recently become a common pollutant in the environment, affect the gut microbiota across fish development. Based on the high-throughput sequencing of the 16S rRNA gene amplicon, we explored the ecological succession of gut microbiota in zebrafish exposed to nanoparticles for three months. The nanoparticles used herein including titanium dioxide nanoparticles (nTiO2, 100 μg/L), zinc oxide nanoparticles (nZnO, 100 μg/L), and selenium nanoparticles (nSe, 100 μg/L). Our results showed that nanoparticles exposure reduced the alpha diversity of gut microbiota at 73–90 days post-hatching (dph), but showed no significant effects at 14–36 dph. Moreover, nTiO2 significantly (p < 0.05) altered the composition of the gut microbial communities at 73–90 dph (e.g., decreasing abundance of Cetobacterium and Vibrio). Moreover, we found that homogeneous selection was the major process (16.6–57.8%) governing the community succession of gut microbiota. Also, nanoparticles exposure caused topological alterations to microbial networks and led to increased positive interactions to destabilize the gut microbial community. This study reveals the environmental effects of nanoparticles on the ecological succession of gut microbiota across zebrafish development, which provides novel insights to understand the gut microbial responses to ENPs over the development of aquatic animals.

The links among Enterocytozoon hepatopenaei infection, growth retardation and intestinal microbiota in different sized shrimp Penaeus vannamei

Increasing evidences have showed that a tight link among pathogen infection, physiological indicators and intestinal microbiota. To investigate effects of Enterocytozoon hepatopenaei (EHP) infection to growth retardation and intestinal microbiota, different sized Pacific white shrimp (Penaeus vannamei) infecting with EHP were studied. The shrimp with big, medium and small sized groups were from same batch of postlarvae and reared in one pond under the same diet and environmental conditions. Number of EHP copies revealed that the more EHP copies the smaller size of shrimp individuals. Denaturing gradient gel electrophoresis (DGGE) profiles showed intestinal bacterial patterns of small sized shrimp were similar to the middle sized shrimp, rather than the big sized shrimp. It implied that intestinal microbiota were influenced by severity of EHP infection and suggested the different sizes of shrimp were due to the successive infection period of EHP. Among the different sized groups, the relative abundance of Vibrio of small group was the highest, suggesting EHP infection could result in higher susceptibility to pathogen invasion. Our findings provided the evidence intestinal bacterial patterns altered by infection of EHP, the more EHP copies the smaller size of shrimp, and different sized individuals due to successive infection period of EHP.

Functional characterization of arginine metabolic pathway enzymes in the antibacterial immune response of penaeid shrimp

Arginine metabolism pathway enzymes and products are important modulators of several physiological processes in animals, including immune response. Although some components of the arginine metabolic pathway have been reported in penaeid shrimps, no systematic study has explored all the key pathway enzymes involved in shrimp antimicrobial response. Here, we explored the role of the three key arginine metabolism enzymes (nitric-oxide synthase (NOS), arginase (ARG), agmatinase (AGM)) in Penaeus vannamei antimicrobial immunity. First, P. vannamei homologs of ARG and AGM (PvARG and PvAGM) were cloned and found to be evolutionally conserved with invertebrate counterparts. Transcript levels of PvARG, PvAGM, and PvNOS were ubiquitously expressed in healthy shrimp tissues and induced in hemocytes and hepatopancreas upon challenge with Gram-negative (Vibrio parahaemolyticus) and Gram-positive (Streptoccocus iniae) bacteria, suggesting their involvement in shrimp antimicrobial immune response. Besides, RNA interference knockdown and enzyme activity assay revealed an antagonistic relationship between PvARG/PvAGM and PvNOS, while this relationship was broken upon pathogen stimulation. Interestingly, knockdown of PvNOS increased Vibrio abundance in shrimp hemolymph, whereas knockdown of PvAGR reduced Vibrio abundance. Taken together, our present data shows that homologs of the key arginine metabolism pathway enzymes in penaeid shrimp (PvARG, PvAGM, and PvNOS) work synergistically and/or antagonistically to modulate antibacterial immune response.

Understanding the host-microbe-environment interactions: Intestinal microbiota and transcriptomes of black tiger shrimp Penaeus monodon at different salinity levels

Disease outbreak has continued to be a major challenge for shrimp aquaculture industry. In recent years, manipulation of gut microbiota has been shown to improve the health of host shrimp and disease resistance. Therefore, understanding how various factors can shape the gut microbiota of shrimp is crucial for future utilization of gut microbiota as tools for disease controls. The salinity of the rearing environment can potentially affect shrimp gut microbiota as well as the host-microbe interactions. The effects of salinity adaptation on intestinal microbiota and transcriptomes of juvenile black tiger shrimp Penaeus monodon were examined in this experiment.Intestinal microbiota and transcriptomic profiles from juvenile black tiger shrimp of the same cohort adapted to three different salinity levels were examined using 16S rDNA amplicon sequencing and RNA sequencing, respectively. Shrimp were acclimatized from the original 20 ppt salinity to either 10 ppt or 30 ppt over a period of 10 days, and intestinal samples were collected on Day 0, Day 10, and Day 20 after reaching the target salinity. Across all salinity levels, the dominant phyla composition in the intestine of shrimp was relatively similar with Proteobacteria (83.4%), Bacteroidetes (8.1%), Planctomycetes (3.2%), Verrucomicrobia (2.5%), and Firmicutes (1.5%). The most abundant genus was Vibrio. While it can be found at all salinity levels, a relative abundance of Vibrio was lower at 10 ppt than at higher salinity. A shift toward the higher relative abundance of Vibrio ASVs belonging to the Harveyi clade was observed at higher salinity. On the other hand, the relative abundance of Shewanella was higher at 10 ppt than at higher salinity. Other dominant genera in the intestines not affected by the change in salinity were Pseudoaltermonas and Tenacibaculum. The shift in the rearing water microbiota with different salinity levels was also observed. The most abundant intestinal transcripts responding to different salinity levels based on GO classification were intracellular anatomical structure (cellular component), protein binding (molecular function), and organic substance metabolic process (biological function). Genes involved with stress and immune responses were differentially expressed, and correlations between potentially pathogenic Vibrio and genes relating to innate immunity and peritrophic matrix were observed.The results confirmed the influence of rearing water salinity on both the intestinal microbiota and transcriptomes of shrimp. Efforts to shape the microbiota of aquatic animals should take into consideration the rearing salinity to ensure its efficacy. Using multi-omic platform allowed for better understanding of the microbiota and the host-microbe interaction, which will help support the sustainability of aquaculture production.

Potential of probiotics Bacillus subtilis to reduce ammonia levels, Vibrio sp abundance, and increased production performance of Seaworm (Nereis sp) under laboratory scale

This study aims to determine the potential of Bacillus subtilis probiotic in reducing levels of ammonia, Vibrio sp, and increased production performance in seaworm cultivation (Nereis sp.) under laboratory scale. Observation of the performance of seaworms (Nereis sp.) was carried out every 10 days which included weight gain (gr), length (cm), total biomass (gr), total bacteria (CFU/mL), total Vibrio sp. (CFU/mL), and total Bacillus subtilis (CFU/mL). Water quality measurements include temperature, dissolved oxygen (DO), pH, ammonia, and total organic matter (TOM). Application of probiotics Bacillus subtilis has the potential to reduce ammonia concentration, increase growth, and reduce the abundance of Vibrio sp under laboratory-scale seaworm cultivation. P3 treatment (0.01 mL with a probiotic density of 106 CFU/mL) gave the best results by being able to reduce the ammonia concentration by 47.5%. In summary, the probiotic application using the bacteria Bacillus subtilis with different densities able to provide good results in supporting production performance, maintaining the abundance of Vibrio sp., and reducing ammonia concentration in seaworm cultivation. This is the first study to report the performance of seaworm production using probiotic agent, research is still needed to determine the digestive enzyme activity of seaworms given probiotics.

Occurrence and dynamics of potentially pathogenic vibrios in the wet-dry tropics of northern Australia

Bacteria from the Vibrio genus are a ubiquitous component of coastal and estuarine ecosystems with several pathogenic Vibrio species displaying preferences for warm tropical waters. We studied the spatial and temporal abundance of three key human potential pathogens V. parahaemolyticus, V. cholerae and V. vulnificus in northern tropical Australia, over the wet and dry seasons, to identify environmental parameters influencing their abundance. Quantitative PCR (qPCR) analysis revealed that V. parahaemolyticus occurred more frequently and in higher abundance than V. cholerae and V. vulnificus across all locations examined. All three species were more abundant during the wet season, with V. parahaemolyticus abundance correlated to temperature and conductivity, whereas nutrient concentrations and turbidity best explained V. vulnificus abundance. In addition to these targeted qPCR analyses, we assessed the composition and dynamics of the entire Vibrio community using hsp60 amplicon sequencing. Using this approach, 42 Vibrio species were identified, including a number of other pathogenic species such as V. alginolyticus, V. mimicus and V. fluvialis. The Vibrio community was more diverse in the wet season, with temperature and dissolved oxygen as the key factors governing community composition. Seasonal differences were primarily driven by a greater abundance of V. parahaemolyticus and V. vulnificus during the wet season, while spatial differences were driven by different abundances of V. harveyi, V. campbellii, V. cholerae and V. navarrensis. When we related the abundance of Vibrio to other bacterial taxa, defined using 16S rRNA gene amplicon sequencing, V. parahaemolyticus was negatively correlated to several taxa, including members of the Rickettsiales and Saccharimonadales, while V. vulnificus was negatively correlated to Rhobacteriaceae and Cyanobiaceae. In contrast, V. alginolyticus, V. harveyi and V. mediterranei were all positively correlated to Cyanobacteria. These observations highlight the dynamic nature of Vibrio communities and expands current understanding of the processes governing the occurrence of potentially pathogenic Vibrio spp. in tropical coastal ecosystems.

Effect of High-Fat Diet on the Intestinal Flora in Letrozole-Induced Polycystic Ovary Syndrome Rats.

Aim The aim of this study was to explore whether letrozole and high-fat diets (HFD) can induce obese insulin-resistant polycystic ovary syndrome (PCOS) with intestinal flora dysbiosis in a rat model. We compared the changes in the intestinal flora of letrozole-induced rats fed with HFD or normal chow, to explore the effects of HFD and letrozole independently and synergistically on the intestinal flora. Methods Five-week-old female Sprague Dawley (SD) rats were divided into four groups: control (C) group fed with regular diet; L1 group administered with letrozole and fed with regular diet; L2 group received letrozole and fed with HFD; and HFD group fed with HFD. At the end of the experiment, ovarian morphology, hormones, metabolism, oxidative stress, and inflammatory status of all rats were studied. 16S rDNA high-throughput sequencing was used to profile microbial communities, and various multivariate analysis approaches were used to quantitate microbial composition, abundance, and diversity. Results Compared to the C group, the increased plasma fasting insulin and glucose, HOMA-IR, triglyceride, testosterone, and malondialdehyde were significantly higher in the L2 group, while high-density lipoprotein cholesterol was significantly lower in the L1 group and L2 group. The indices of Chao1 and the Abundance-based Coverage Estimator (ACE) (α-diversity) in the L2 and HFD groups were significantly lower than that in the C group. Bray–Curtis dissimilarity based principal coordinate analysis (PCoA) plots and analysis of similarities (ANOSIM) test showed obvious separations between the L2 group and C group, between the HFD group and C group, and between the L2 and HFD groups. At the phylum level, Firmicutes and ratio of Firmicutes and Bacteroidetes (F/B ratio) were increased in the L2 group; Bacteroidetes was decreased in the L2 and HFD groups. No significant differences in bacterial abundance between the C group and L1 group were observed at the phylum level. Based on linear discriminant analysis (LDA) effect size (LEfSe) analysis, the bacterial genera (the relative abundance > 0.1%, LDA > 3, p < 0.05) were selected as candidate bacterial signatures. They showed that the abundance of Vibrio was significantly increased in the L1 group; Bacteroides and Phascolarctobacterium were enriched in the HFD group, and Bacteroides, Phascolarctobacterium, Blautia, Parabacteroides, Akkermansia [Ruminococcus]_torques_group, and Anaerotruncus were enriched in the L2 group. Conclusion The effect of letrozole on intestinal flora was not significant as HFD. HFD could destroy the balance of intestinal flora and aggravate the intestinal flora dysbiosis in PCOS. Letrozole-induced rats fed with HFD have many characteristics like human PCOS, including some metabolic disorders and intestinal flora dysbiosis. The dysbiosis was characterized by an increased Firmicutes/Bacteroidetes ratio, an expansion of Firmicutes, a contraction of Bacteroidetes, and the decreased microbial richness. Beta-diversity also showed significant differences in intestinal microflora, compared with control rats.

Viable Putative Vibrio vulnificus and parahaemolyticus in the Pensacola and Perdido Bays: Water Column, Sediments, and Invertebrate Biofilms

Vibriosis is the general term for human illnesses caused by infection of pathogenicVibriospecies.Vibrio vulnificus(Vv) andparahaemolyticus(Vp) are two problematic waterborne pathogens that have yet to be enumerated in northwest Florida coastal Gulf of Mexico estuaries. In this regionally novel study, we surveyed 43 locations in two subtropical estuarine systems, Perdido Bay and Pensacola Bay, over seven dates in winter 2020. Sampling included three substrate types: surface waters, sediments, and invertebrate biofilms. We determined baseline abundances of presumptive viableVvandVpappearing as colonies on CHROMagar (Vv, blue;Vp, purple).Vvwas detected in 37 out of 43 water samples, with maximum levels of 3,556 CFU/mL.Vpwas only detected in 15 water samples, with a maximum concentration of 8,919 CFU/mL. Sediments containedVvin all but one sample, with concentrations ranging from 121 to 607,222 CFU/mL. In contrast,Vpwere only detected in 33 sediment samples, where concentrations ranged from 28 to 77,333 CFU/mL. Opportunistically-sampled surface swabs (biofilms), collected from shells (either oyster or barnacle) and polychaete worms found in sediment samples, contained on average 7,735 and 1,490 CFU/mL ofVvandVp, respectively. Surface waterVvabundances covaried with bottom water pH, maximum prior cumulative wind speeds, and tidal coefficient on the day of sampling.Vpsurface water abundances negatively correlated with surface water salinity, surface water pH, and bottom water pH and positively correlated with total surface dissolved inorganic and total Kjeldahl nitrogen concentrations, and wind. Spatially, there was large variation inVibriodensities in surface waters; abundances of both species were strongly correlated with wind, suggesting resuspension was important. Sedimentary abundances of both putativeVvandVpshared a correlation with one parameter: salinity stratification. Due to the length of this study, temperature was not considered a major factor. This short-term (1 month) study was designed not to enumerate pathogenicVvorVp, but rather to establish the first winter baseline ofVibrioabundances for this region. Determination of these baseline winter cultivable putativeVibrioabundances will be valuable in predicting relative risk factors in each waterbody of interest.

Distinct bacterial communities in the environmental water, sediment and intestine between two crayfish-plant coculture ecosystems.

Microorganisms are an important part of productivity, water quality, and biogeochemical cycles in an aquaculture ecosystems and play a key role in determining the growth and fitness of aquaculture animals. Coculture ecosystems are widely applied with great significance in agricultural production worldwide. The crayfish-rice coculture ecosystem (CRCE) and crayfish-waterweed coculture ecosystem (CWCE) are two high-profile artificial ecosystems for crayfish culture. However, the bacterial communities of the environmental water, sediment, and intestine in the CRCE and CWCE remain elusive. In this study, we investigated the diversity, composition, and function of bacterial communities in water, sediment, and intestine samples from the CRCE to CWCE. The physicochemical factors of water [such as ORP (oxidation-reduction potential), TC (total carbon), TOC (total oxygen carbon), and NO3--N] and sediment [such as TC, TOC, TN (total nitrogen), and TP (total phosphate)] were significantly different in the CRCE and CWCE. The abundances of Proteobacteria, Actinobacteria, Verrucomicrobia, Cyanobacteria, Chlorobi, Chloroflexi, and Firmicutes were significantly different in the water bacterial communities of the CRCE and CWCE. The abundance of Vibrio in the crayfish intestine was higher in the CRCE than in the CWCE. The most abundant phyla in the CRCE and CWCE sediment were Proteobacteria and Bacteroidetes. The abundances of genes involved in transporters and ABC transporters were different in water of CRCE and CWCE. The abundances of genes involved in oxidative phosphorylation were significantly higher in the crayfish intestine of the CRCE than in that of the CWCE. Furthermore, the functional genes associated with carbon metabolism were significantly more abundant in the sediment of the CRCE than in that of the CWCE. Spearman correlation analysis and redundancy analysis (RDA) showed that the bacterial communities of the water and sediment in the CRCE and CWCE were correlated with environmental factors (pH, total carbon (TC), total oxygen carbon (TOC), total nitrogen (TN), and total phosphorus (TP)). Our findings showed that the composition, diversity and function of the bacterial communities were distinct in the environmental water, sediment, and intestine of the CRCE and CWCE crayfish coculture ecosystems due to their different ecological patterns. These results can help guide healthy farming practices and deepen the understanding of bacterial communities in crayfish-plant coculture ecosystems from the perspective of bacterial ecology. KEY POINTS: • The composition of bacterial communities in the environmental water, sediment, and intestine of the CRCE and CWCE were distinct. ̉• The abundances of genes involved in transporters and ABC transporters were different in the water of the CRCE and CWCE. • The bacterial communities of the water and sediment in the CRCE and CWCE were correlated with some environmental factors.

Effect of mangrove restoration on sediment properties and bacterial community.

Mangrove reconstruction is an efficient approach for mangrove conservation and restoration. The present study aimed to explore the effects of mangrove reconstruction on sediment properties and bacterial community. The results showed that mangrove restoration greatly promoted sediment fertility, whereas the improvements were more obvious induced by Kandelia obovata when compared to Avicennia marina. In all the samples, the dominant top5 bacterial group were Proteobacteria (48.31-54.52%), Planctomycetes (5.98-8.48%), Bacteroidetes (4.49-11.14%) and Acidobacteria (5.69-8.16%). As for the differences among the groups, the relative abundance of Chloroflexi was higher in the sediments of K. obovata, while Bacteroidetes was more abundant in A. marina group. Furthermore, the two bacterial genera (Rhodoplanes and Novosphingobium) were more dominant in the sediments of K. obovata, while the sediments of A. marina contained higher abundance of Vibrio and Marinobacterium. Besides, bacterial community was highly correlated with mangrove species and sediment property and nutrient status. The results of this study would provide a better understanding of the ecological benefits of mangroves and highlighted the information on biogeochemical processes driven by mangrove restoration and microorganisms.

Dietary glycerol monolaurate improved the growth, activity of digestive enzymes and gut microbiota in zebrafish (Danio rerio)

Microbial recurrent infections and antimicrobial resistance have motivated the researchers to explore bioactive compounds as safe alternative antimicrobials to target pathogenic microorganisms. Interest in finding new biologically active substances to replace conventional antibiotics in aquatic feed has rapidly increased, since the misuse or overuse of antibiotics produced antibiotic resistance. Glycerol monolaurate (GML), has attracted attention of researchers due to its growth-promoting and immunomodulatory potential by exerting beneficial effects on the gut microbiota and host health. This study aimed to evaluate the effects of dietary GML using as a feed additive on the growth performance, blood lipid profile, hepatic lipid deposition, body composition, digestive enzymes, serum anti-inflammatory activities, and gut microbiota of zebrafish. The study’s findings showed that diet supplemented with 750 mg kg−1 of GML, significantly improved the growth performance, feed utilization and intestinal lipase activity, as well as body crude lipid content without inducing hepatic fat accumulation. GML supplementation also promoted the serum anti-inflammatory potential by elevating the level of TGF-β1 and IL-10. Moreover, dietary supplementation of GML positively restructured the intestinal microbial ecology by improving the relative abundance of several favorable bacteria, including Cetobacterium, Shewanella, and Vibrio at the genus level. Conclusively, study’s findings suggest that GML supplementation contributes in improving the growth, digestive enzymes activities, anti-inflammatory potential, and gut microbiota, indicating GML promising potential as a feed additive in aquaculture nutrition.

Characteristics of soil bacterial and fungal communities on interval seawater covering Linchang Island, China.

Characterization of microbial communities is important for understanding the soil biodiversity distribution affected by environmental factors. Here, we combined high-throughput sequencing of 16S rDNA and ITS to investigate the composition of bacterial and fungal communities in interval seawater covering Linchang Island, China. We compared the microbial communities in the soil of three sample points from the southern part to the northern part. No difference was observed in microbial abundance, richness and diversity in those three different locations. In addition, weighted and unweighted UniFrac distances revealed that three soil samples could not be separated from each other, even if the LCNS sample had significantly lower organic matter (OM), sodium and sulfate contents than the LCSS and LCMS samples. This result indicated that the microbial community of the soil may be influenced more strongly by interval seawater than by soil chemical characteristics. The bacterial phyla Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes were the four most abundant phyla in all samples, accounting for 83.22% of the microbial community. Escherichia-Shigella and Vibrio were abundant in the samples and accounted for 1.17% and 0.27%, respectively. Fungal structure, phylogenetic diversity, richness, and bacterial structure had a significant negative relationship with Vibrio abundance. In addition, Vibrio showed negative correlations with the genera Simiduia, Microbulbifer and Haliangium. The results reveal that the re-shaped microbiome and introduced typical microbes could be strategies for inhibiting Vibrio in the soil of Linchang Island.

Supplementation of tuna hydrolysate and insect larvae improves fishmeal replacement efficacy of poultry by-product in Lates calcarifer (Bloch, 1790) juveniles

The effects of feeding different levels of poultry by-product meal (PBM) replacing fishmeal (FM) protein, supplemented with tuna hydrolysate (TH) and Hermetia illucens (HI) larvae, on the growth, fillet quality, histological traits, immune status, oxidative biomarker levels and gut microbiota of juvenile barramundi, Lates calcarifer were investigated for six weeks. Barramundi were fed four isonitrogenous and isolipidic diets in which a FM based diet was used as the Control diet (Diet1) and compared with other non-FM diets containing 80%, 85% and 90% PBM along with the concurrent supplementation of 5% and/or 10% TH and HI larvae meal. These treatment diets were designated as 80PBM10TH+10HI (Diet2), 85PBM5TH+10HI (Diet3) and 90PBM5TH+5HI (Diet4). The growth and condition factor of fish fed 80PBM10TH+10HI and 85PBM5TH+10HI were significantly higher than the Control. Total saturated, monounsaturated and polyunsaturated fatty acid retention in the fish muscle increased in fish fed PBM-based diets, supplemented with TH and HI larvae meal, with no adverse effect on post-harvest characteristics such as texture and colour of fish fillets. Improvement in serum total bilirubin and total protein content was found in all fish fed TH and HI larvae supplemented PBM. Similarly, immune response showed a significant increase in fish fed non-FM test diets than the Control. In the distal intestine, supplementation of any quantities of TH and HI larvae to PBM led to an increase in the microvilli density and neutral mucins while the number of goblet cells in the skin were unchanged. Liver, kidney, and spleen histology demonstrated a normal structure with no obvious changes in response to all test diets. Bacterial diversity increased in fish fed Diets 2 and 3 with a high abundance of Proteobacteria in Diets 1 and 4 and Firmicutes in Diets 2 and 3. The fish on test diets showed a lower abundance of genus Vibrio. Fish fed TH and HI larvae supplemented PBM diets showed lower infection rate to V. harveyi than the Control. Collectively, concurrent supplementation of TH and HI larvae could improve the quality of PBM diets with positive effects on growth, fillet quality, intestinal health, immunity, and disease resistance.

Evaluation of different dietary n ‐3 lc‐pufa on the growth, intestinal health and microbiota profile of golden pompano ( Trachinotus ovatus )

The omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are essential fatty acids for marine fish. This study aimed to evaluate different dietary n-3 LC-PUFA on the growth, intestinal health and microbiome in carnivorous marine fish Trachinotus ovatus. Three diets, respectively, supplemented with fish oil, EPA-enriched oil and DHA-enriched oil were fed juvenile T. ovatus for 10 weeks. The results showed that the three groups showed no difference in the growth, histology and digestive enzyme activities of anterior intestine. Moreover, the intestinal ACP and ALP activities and tnfɑ mRNA level were increased in the EPA-enriched group, whereas the serum diamine oxidase activity and intestinal lysozyme activity and malondialdehyde content were decreased in both EPA- and DHA-enriched groups. Meanwhile, these two diets also down-regulated the mRNA expression of Mucin 2, Mucin 13, hes1-b, Krueppel-like factor 4 and Occludin, and up-regulated the zonula occludens-1 mRNA levels in intestine. Moreover, the two groups significantly decreased the intestinal Vibrio abundance and increased the probiotic proportions, especially in the EPA-enriched group. These results indicate dietary n-3 LC-PUFA would facilitate normal intestinal function and probiotics profiles of T. ovatus, and the EPA-enriched group appears to be more positive.

Microbiome Analyses Demonstrate Specific Communities Within Five Shark Species.

Profiles of symbiotic microbial communities (“microbiomes”) can provide insight into the natural history and ecology of their hosts. Using high throughput DNA sequencing of the 16S rRNA V4 region, microbiomes of five shark species in South Florida (nurse, lemon, sandbar, Caribbean reef, and tiger) have been characterized for the first time. The microbiomes show species specific microbiome composition, distinct from surrounding seawater. Shark anatomical location (gills, teeth, skin, cloaca) affected the diversity of microbiomes. An in-depth analysis of teeth communities revealed species specific microbial communities. For example, the genus Haemophilus, explained 7.0% of the differences of the teeth microbiomes of lemon and Caribbean reef sharks. Lemon shark teeth communities (n = 11) contained a high abundance of both Vibrio (10.8 ± 26.0%) and Corynebacterium (1.6 ± 5.1%), genera that can include human pathogenic taxa. The Vibrio (2.8 ± 6.34%) and Kordia (3.1 ± 6.0%) genera and Salmonella enterica (2.6 ± 6.4%) were the most abundant members of nurse shark teeth microbial communities. The Vibrio genus was highly represented in the sandbar shark (54.0 ± 46.0%) and tiger shark (5.8 ± 12.3%) teeth microbiomes. The prevalence of genera containing potential human pathogens could be informative in shark bite treatment protocols and future research to confirm or deny human pathogenicity. We conclude that South Florida sharks host species specific microbiomes that are distinct from their surrounding environment and vary due to differences in microbial community composition among shark species and diversity and composition among anatomical locations. Additionally, when considering the confounding effects of both species and location, microbial community diversity and composition varies.

Effects of dietary hydrolyzable tannins on growth performance, antioxidant capacity, intestinal microflora and resistance against Vibrio parahaemolyticus of juvenile Pacific white shrimp, Litopenaeus vannamei (Boone, 1931)

Tannins have great potential as an alternative to in-feed antibiotics. However, no study has investigated the effects of tannins on shrimp. The present study assessed the eff ;ects of hydrolyzable tannins (HTs) fed at different inclusion levels (F0: control, F0.5: 0.05 %, F1: 0.1 %, F1.5: 0.15 % and F2: 0.2 % (g−1 feed) on the growth performance, antioxidant capacity, immune response, intestinal microflora and resistance to Vibrio parahaemolyticus of juvenile Pacific white shrimp (Litopenaeus vannamei). After 60 days of the feeding trial, a significant increase (P < 0.05) of weight gain rate (WGR), specific growth rate (SGR), activities of alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD) and trypsin in serum and hepatopancreas, and the expression level of catalase (CAT), Cu/Zn superoxide dismutase (Cu/Zn-SOD) and glutathione peroxidase (GPx) gene in the hepatopancreas of 0.15 % HT treated groups were achieved. The dietary supplementation of HTs also changed the composition of intestinal microflora. At the phylum level, Proteobacteria accounted for the majority of bacteria, followed by Firmicutes, Bacteroidetes and Actinobacteria. At the genus level, Stenotrophomonas, Ruegeria, and Photobacterium were dominant in the F0.5, F1, and F1.5 groups, respectively. The relative abundance of Vibrio and Carboxylicivirga decreased in the intestines of shrimp fed with HTs diets. Furthermore, F1.5 group showed the highest relative percent survival value (80 %) (P < 0.05), which indicates that the supplementation of 0.15 % HTs in challenge test significantly enhanced the resistance of shrimp against V. parahaemolyticus infection after 24 h. These results indicated that 0.15 % HTs could remarkably improve the growth performance, antioxidant capacity, intestinal microflora, and resistance against V. parahaemolyticus of L. vannamei, and can be a potential feed additive for shrimp in aquaculture. According to our study, the optimal dietary supplementation dosage of HTs is 0.15 % feed in diets.

Disentangling the abundance and structure of Vibrio communities in a semi-enclosed Bay with mariculture (Dongshan Bay, Southern China)

The genus Vibrio contains a diverse group of heterotrophic bacteria, which are members of ubiquitous and abundant microbial communities in coastal ecosystems. Vibrio has been frequently found in a wide range of marine environments either by employing Vibrio-specific 16S rRNA sequencing or culturing methods. A combination of molecular and cultivation-dependent methods was developed to more precisely discriminate between different members of the genus Vibrio in seawater. This newly developed assay was subsequently applied to characterize Vibrio community composition in surface water at 18 mariculture sites. It Substantially improved the taxonomic resolution of Vibrio species when compared to traditional 16S rRNA analysis. Our qPCR and cultivation analyses revealed that average Vibrio abundance (Vibrio 16S rRNA gene copy numbers: 3.46 × 106 to 6.70 × 106 copies L−1) and live cell numbers (5.65 × 104–5.75 × 105 cfu mL−1) are significantly related to pH. Total bacteria and Vibrio-specific 16S rRNA metabarcode sequenceing resulted in a total of 10 and 32 operational taxonomic units (OTUs), respectively, and 15 Vibrio species were identified by targeted cultivation of Vibrio strains, with Vibrio fortis and V. brasiliensis dominating in the mariculture areas. The purpose of this study was to combine several analytical methods to improve current sequence-based Vibrio community surveys, and to prove for the effectiveness of this methodological approach comprehensively testing for Vibrio dynamics in different coastal environments.

Vibrio Colonization Is Highly Dynamic in Early Microplastic-Associated Biofilms as Well as on Field-Collected Microplastics.

Microplastics are ubiquitous in aquatic ecosystems and provide a habitat for biofilm-forming bacteria. The genus Vibrio, which includes potential pathogens, was detected irregularly on microplastics. Since then, the potential of microplastics to enrich (and serve as a vector for) Vibrio has been widely discussed. We investigated Vibrio abundance and operational taxonomic unit (OTU) composition on polyethylene and polystyrene within the first 10 h of colonization during an in situ incubation experiment, along with those found on particles collected from the Baltic Sea. We used 16S rRNA gene amplicon sequencing and co-occurrence networks to elaborate the role of Vibrio within biofilms. Colonization of plastics with Vibrio was detectable after one hour of incubation; however, Vibrio numbers and composition were very dynamic, with a more stable population at the site with highest nutrients and lowest salinity. Likewise, Vibrio abundances on field-collected particles were variable but correlated with proximity to major cities. Vibrio was poorly connected within biofilm networks. Taken together, this indicates that Vibrio is an early colonizer of plastics, but that the process is undirected and independent of the specific surface. Still, higher nutrients could enhance a faster establishment of Vibrio populations. These parameters should be considered when planning studies investigating Vibrio on microplastics.