Host-associated probiotics(HAPs)are bacteria originally isolated from rearing water or the host's gastrointestinal tract in order to enhance the host's growth and health.This study investigated the HAP potenti...Host-associated probiotics(HAPs)are bacteria originally isolated from rearing water or the host's gastrointestinal tract in order to enhance the host's growth and health.This study investigated the HAP potential of Bacillus sp.PM8313,isolated from wild red sea bream(Pagrus major),through characterization and feeding trials.Results based on in vitro tests showed that PM8313 is safe,confirming its hemolytic,cytotoxic,and antibiotic resistance.In addition,PM8313 showed advantages as a probiotic with high viability in the gastrointestinal model and a high cell adhesion rate.Whole-genome sequencing demonstrated that PM8313 has a 4,615,871 bp single circular chromosome and a guaninecytosine content of 45.25%.It also showed the absence of genes encoding virulence factors,such as cytotoxin,enterotoxin,hemolysin,sphingomyelinase,and phospholipase.In the feeding trial,a supplemental diet of 1×10^(8)CFU/g PM8313 positively altered the weight gain,digestive enzyme activity,and intestinal microbiota composition of red sea bream.Analysis of nonspecific immune parameters and immune-related gene expression,and a challenge test showed that PM8313 supplementation increases immunity and pathogenic bacteria resistance.Our findings suggest that PM8313 should be considered for application as a novel HAP to red sea bream aquaculture.展开更多
An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder.Five semi-purified test diets were formulated to contain different protein levels(CP)including 42.7%,4...An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder.Five semi-purified test diets were formulated to contain different protein levels(CP)including 42.7%,47.4%,53.3%,58.8%,and 64.5%(dry matter),named as CP42.7,CP47.4,CP53.3,CP58.8,and CP64.5,respectively.Five hundred and twenty-five juveniles(6.0±0.1 g)were randomly distributed into 15 tanks(300 L tanks),resulting in 35 fish per tank(n-3 tanks).Fish were fed the test diets 5 times per day until satiation.The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels(P<0.05).Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets(P<0.05).Fish fed the CP53.3,CP58.8,and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets(P<0.05).The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%.Taken together,it is suggested that the dietary protein level of 58.8%is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder.展开更多
基金financially supported by the grant (R2022016) from the National Institute of Fisheries Science,Republic of Koreathe National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2022R1A2C1012655).
文摘Host-associated probiotics(HAPs)are bacteria originally isolated from rearing water or the host's gastrointestinal tract in order to enhance the host's growth and health.This study investigated the HAP potential of Bacillus sp.PM8313,isolated from wild red sea bream(Pagrus major),through characterization and feeding trials.Results based on in vitro tests showed that PM8313 is safe,confirming its hemolytic,cytotoxic,and antibiotic resistance.In addition,PM8313 showed advantages as a probiotic with high viability in the gastrointestinal model and a high cell adhesion rate.Whole-genome sequencing demonstrated that PM8313 has a 4,615,871 bp single circular chromosome and a guaninecytosine content of 45.25%.It also showed the absence of genes encoding virulence factors,such as cytotoxin,enterotoxin,hemolysin,sphingomyelinase,and phospholipase.In the feeding trial,a supplemental diet of 1×10^(8)CFU/g PM8313 positively altered the weight gain,digestive enzyme activity,and intestinal microbiota composition of red sea bream.Analysis of nonspecific immune parameters and immune-related gene expression,and a challenge test showed that PM8313 supplementation increases immunity and pathogenic bacteria resistance.Our findings suggest that PM8313 should be considered for application as a novel HAP to red sea bream aquaculture.
基金This work was supported by a grant from the National Institute of Fisheries Science(R2021040).
文摘An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder.Five semi-purified test diets were formulated to contain different protein levels(CP)including 42.7%,47.4%,53.3%,58.8%,and 64.5%(dry matter),named as CP42.7,CP47.4,CP53.3,CP58.8,and CP64.5,respectively.Five hundred and twenty-five juveniles(6.0±0.1 g)were randomly distributed into 15 tanks(300 L tanks),resulting in 35 fish per tank(n-3 tanks).Fish were fed the test diets 5 times per day until satiation.The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels(P<0.05).Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets(P<0.05).Fish fed the CP53.3,CP58.8,and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets(P<0.05).The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%.Taken together,it is suggested that the dietary protein level of 58.8%is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder.
