间歇性饥饿对南美白对虾生物絮团养殖系统中微生物群落结构、水质和生长的影响OACSTPCD

Diet restriction has been used as a strategy to reduce the feed and labor cost in the aquaculture.The compensatory growth is widely present in mammals,fish and crustaceans.Based on full compensatory growth ability of Litopenaeus vannamei,the biofloc technology combined with diet restriction were applied to L.vannamei breeding.The effects of intermittent fasting on the microflora structure,water quality and growth parameters of L.vannamei in a biofloc system were investigated.The L.vannamei were randomly assigned into 4 groups(each with 3 replicates):Group 1 was the control group,normally fed with basal L.vannamei feed.Group 2 was the biological floc group,fed with L.vannamei feed and brown sugar(70%of the feed),and the C/N ratio was 12 in water.Group 3 was the probiotic and biological floc group,besides feed and brown sugar,Bacillus licheniformis(concentration was 1.2×105 CFU/mL in water)was also added;Group 4 was the intermittent starved group,starved for 2 d and re-feeding for 5 d.The results indicated the biological floc sedimentation in water showed an increasing trend.At the 4th week,the formation of biological floc in group 2,3 and 4 were significantly higher than that in group 1(P＜0.05),respectively.The operational taxonomic units(OTU)of microflora in group 1,group 2,group 3 and group 4 were 3501,6386,5387 and 6577,with high throughput sequencing,respectively.The unique OTU numbers were 165,463,362 and 592,respectively,and 173 OTUs were shared by these 4 groups.The α diversity order of the bacterial community from high to low was:Group 4＞group 2＞group 3＞group 1.The abundance analysis at genus level showed that the most dominant flora of group 1 was Georgenia(20.2%),followed by Hydrogenophaga(13.5%)and Pseudomonas(13.2%).In group 2,the highest abundance was Pseudomonas(39%),followed by Georgenia(9.1%)and Brevundimonas(7.0%).In group 3,the highest abundance was Brevundimonas(38.4%),followed by Microbacterium(5.7%)and Methyloversatilis(5.7%).In group 4,the highest abundance was Alishewanella(21.0%),followed by Pseudomonas(15.5%)and Exiguobacterium(6.8%).The concentration of ammonia nitrogen and nitrite nitrogen significantly decreased in groups 2,3 and 4(P＜0.05).The feed conversion rate(FCR)of group 4 was significantly higher than 3 other groups(P＜0.05).The results showed the biofloc technology based on compensatory growth could effectively increase the richness and diversity of microflora,optimize the composition of the microbial community,reduce the concentration of ammonia nitrogen and nitrite nitrogen in aquaculture water of L.vannamei,thereby to optimize aquaculture water quality,and effectively increase the feed conversion rate.The results were conducive to elucidating the mechanism of biofloc optimizing water quality,and provide experiental data for the application of the biofloc technology based on compensatory growth in L.vannamei culture.