A total of 25 strains were isolated from the intestinal tract of Mystus macropterus. The inhibitory effects of extracellular enzyme activity to common aquat- ic pathogenic bacteria were screened. A probiotic DQHY -7 s...A total of 25 strains were isolated from the intestinal tract of Mystus macropterus. The inhibitory effects of extracellular enzyme activity to common aquat- ic pathogenic bacteria were screened. A probiotic DQHY -7 strain was isolated, and its safety was detected. DQHY -7 strain was preliminarily identified by mor- phological observation, and physiological and biochemical test. Research results showed that DQHY -7 strain had relatively strong production capacities of amylase, cellulase and protease, and could restrict the growth of Escherichia coli, Aeromonas hydrophila and Pseudomonas fluorescens. Results of acute toxicity test showed that 1. 0 × 108 CFU/mL DQHY -7 bacterial suspension showed no pathogenicity to M. macropterus. According to the colony growth pattern and physiological-bio- chemical characteristics of DQHY -7, the strain was identified to be Bacillus subtilis. Research results showed that DQHY -7 strain could be used as a new candi- date strain for feeding microecologicalagent.展开更多
In this study,thirty-six individuals of Acheilognathus macropterus were collected from the Heilongjiang River,the Yangtze River,and the Nandujiang River.Partial mitochondrial cytochrome b gene region(636 base pair)was...In this study,thirty-six individuals of Acheilognathus macropterus were collected from the Heilongjiang River,the Yangtze River,and the Nandujiang River.Partial mitochondrial cytochrome b gene region(636 base pair)was sequenced to these samples and 22 haplo-types were found.With A.chankaensis and A.tokinensis as outgroups,their relationships were analyzed.The p-distances were calculated with Mega software and a molecular phylogenetic tree was constructed using the neighbor-joining(NJ)method.The proportions of main morphological characters were compared as well.P-distances showed that the genetic differences in A.macropterus samples were far smaller than those between these samples and the outgroups.The molecular phylogenetic tree shows that samples with barbels and those without barbels were intermingled.There was no distinctive difference in proportions of morphological characteristics among them.These results suggested that samples with barbels and those without barbels(formally identified as A.taenianalis)are the same species;A.taenianalis is synonymous with A.macropterus.The thirty-six individuals were grouped into five clades and the positions of the samples in the clades were correspondingly grouped within their geographical distributions.Among the five clades,clades 1 and 5 included samples from the Heilongjiang River and Nandujiang River respectively.The samples from the Yangtze River scattered into clades 2,3,and 4.There were distinctive genetic differences(>5%)among them.Interestingly,the distributions of the 21 samples in these three clades were not correlated to their geographical distributions.It is postulated that these genetic differences were due to the bitterlings’mating choice mechanism,the prozygotic isolation.The genetic differences between the fish from Nandujiang River and those from the mainland indicated that they were separated early.However,the small genetic differences among the samples and the positions of the fish from the Heilonjiang River in the molecular phylogenetic tree indicate that fish in Heilongjiang River might have dispersed from the Yangtze River to that area much later.展开更多
基金Supported by the Planning Project of Basic Scientific Research Funds of Chongqing(2012-esfc-jbky-00405)
文摘A total of 25 strains were isolated from the intestinal tract of Mystus macropterus. The inhibitory effects of extracellular enzyme activity to common aquat- ic pathogenic bacteria were screened. A probiotic DQHY -7 strain was isolated, and its safety was detected. DQHY -7 strain was preliminarily identified by mor- phological observation, and physiological and biochemical test. Research results showed that DQHY -7 strain had relatively strong production capacities of amylase, cellulase and protease, and could restrict the growth of Escherichia coli, Aeromonas hydrophila and Pseudomonas fluorescens. Results of acute toxicity test showed that 1. 0 × 108 CFU/mL DQHY -7 bacterial suspension showed no pathogenicity to M. macropterus. According to the colony growth pattern and physiological-bio- chemical characteristics of DQHY -7, the strain was identified to be Bacillus subtilis. Research results showed that DQHY -7 strain could be used as a new candi- date strain for feeding microecologicalagent.
文摘In this study,thirty-six individuals of Acheilognathus macropterus were collected from the Heilongjiang River,the Yangtze River,and the Nandujiang River.Partial mitochondrial cytochrome b gene region(636 base pair)was sequenced to these samples and 22 haplo-types were found.With A.chankaensis and A.tokinensis as outgroups,their relationships were analyzed.The p-distances were calculated with Mega software and a molecular phylogenetic tree was constructed using the neighbor-joining(NJ)method.The proportions of main morphological characters were compared as well.P-distances showed that the genetic differences in A.macropterus samples were far smaller than those between these samples and the outgroups.The molecular phylogenetic tree shows that samples with barbels and those without barbels were intermingled.There was no distinctive difference in proportions of morphological characteristics among them.These results suggested that samples with barbels and those without barbels(formally identified as A.taenianalis)are the same species;A.taenianalis is synonymous with A.macropterus.The thirty-six individuals were grouped into five clades and the positions of the samples in the clades were correspondingly grouped within their geographical distributions.Among the five clades,clades 1 and 5 included samples from the Heilongjiang River and Nandujiang River respectively.The samples from the Yangtze River scattered into clades 2,3,and 4.There were distinctive genetic differences(>5%)among them.Interestingly,the distributions of the 21 samples in these three clades were not correlated to their geographical distributions.It is postulated that these genetic differences were due to the bitterlings’mating choice mechanism,the prozygotic isolation.The genetic differences between the fish from Nandujiang River and those from the mainland indicated that they were separated early.However,the small genetic differences among the samples and the positions of the fish from the Heilonjiang River in the molecular phylogenetic tree indicate that fish in Heilongjiang River might have dispersed from the Yangtze River to that area much later.
