Managing input C/N ratio to reduce the risk of Acute Hepatopancreatic Necrosis Disease (AHPND) outbreaks in biofloc systems – A laboratory study

Hostins, Bárbara; Wasielesky, Wilson; Decamp, Olivier; Bossier, Peter; Schryver, Peter De

doi:10.1016/j.aquaculture.2019.04.055

Cited by 47 publications

(47 citation statements)

References 44 publications

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“…The concentration in the carbon solution depended on the C/N ratio (w/w); here, the amount of glucose to be added was calculated based on the TAN concentration in the influent. The calculations were done by following methods described by Hostins [20]. Moreover, each reactor was supplemented with 1 mL trace element solution every day.…”

Section: Setup Of Reactor and Operationmentioning

confidence: 99%

“…Heterotrophic and autotrophic bacteria are involved not only in the biomass concentrations but also in nitrification and denitrification in aquaculture systems [17][18][19]. The C/N operational parameter of biofloc systems directly influences the composition of the microbial community in the bioflocs [20]. Previous reports indicated that bioflocs protected against bacterial diseases [21].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Gou

Hong

Deng

et al. 2019

Water

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Application of biofloc technology could effectively treat wastewater. However, the effect of influent carbon to nitrogen ratio (C/N ratio) on water quality and microbial community structure evolution in suspended growth bioreactors (SGBRs) through biofloc technology is still unclear. Here, we show that the total ammonia nitrogen (TAN) and nitrite nitrogen in the effluent of the C/N 10 treatment was significantly higher than that in the C/N 15, C/N 20 and C/N 25 treatments (p < 0.05). Higher TAN removal efficiency was obtained in treatments of C/N 15, C/N 20 and C/N 25, and there was no accumulation of nitrite nitrogen and nitrate nitrogen. Increasing the C/N ratio strengthened the elimination ability of total phosphorus and chemical oxygen demand (COD). The concentrations of TAN and COD first dropped to the lowest level and then increased slightly within one cycle in all treatments. The accumulation of biomass in the reactors increased with the increasing C/N ratio, indicating that a higher C/N ratio was conducive to microbial proliferation. The 16S rRNA sequencing revealed that the microbial community diversity in SGBRs was significantly higher than that in the natural wastewater (P0). The predominant phylum were Proteobacteria, Bacteroidetes and Verrucomicrobia, but Saccharibacteria occupied a dominant position in the late period of the experiment. Pathogens, such as Aeromonas, Acidovorax, Flavobacterium, and Malikia were significantly decreased after high C/N ratio simulative wastewater treating natural wastewater in the reactors. In summary, the water quality and biomass concentrations in SGBRs can be improved under the conditions of influent C/N ratio, equal to or greater than 15.

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Section: Setup Of Reactor and Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Gou

Hong

Deng

et al. 2019

Water

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“…Biofloc can also act as immunostimulants to enhance the shrimp innate immune system and provide protection against microbial pathogens including AHPND-causing V. parahaemolyticus (Crab et al, 2010a;Kim et al, 2014;Bossier and Ekasari, 2017;Sajali et al, 2019). In fact, bioflocs as such can decrease the impact of AHPND V. parahaemolyticus challenge; however, the protective potential depends on operational parameters of the biofloc system (Hostins et al, 2019). In this context, there is an urgent need to systematically unravel the protective mechanisms of a biofloc environment and develop a biofloc system that can control AHPND infection in shrimp aquaculture.…”

Section: Introductionmentioning

confidence: 99%

“…Based on observations on the one hand of V. parahaemolyticus phenotype switching in altered environmental conditions (Kumar et al, 2020) and results of Hostins et al (2019) on the other hand on protective potential of biofloc system against AHPND-causing V. parahaemolyticus, it is hypothesized that a biofloc environment is involved in setting the phenotypic status of AHPND-causing V. parahaemolyticus under both in vitro and in vivo conditions, altering its virulence. This hypothesis was verified using a biofloc-based L. vannamei and V. parahaemolyticus model.…”

Section: Introductionmentioning

confidence: 99%

Biofloc-Based Enhanced Survival of Litopenaeus vannamei Upon AHPND-Causing Vibrio parahaemolyticus Challenge Is Partially Mediated by Reduced Expression of Its Virulence Genes

et al. 2020

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The biofloc system is a relatively new aquaculture technology that offers practical solution to maintain culture water quality by recycling nutrients and improves the health status and resistance of shrimps against microbial infection, yet the mode of action involved remains unclear. This study aimed to unravel the underlying mechanism behind the protective effect of a biofloc system using Litopenaeus vannamei and acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus M0904 strain as a host-pathogen model. The results showed that a biofloc system maintained at a C/N ratio of 15, improves the water quality and contributes to the nutrition of cultured animals as bioflocs might serve as an additional protein source. Furthermore, the study demonstrated that the biofloc system enhances the survival of L. vannamei upon challenge with a V. parahaemolyticus AHPND strain. Remarkably, the results highlight that in the biofloc system, AHPND-causing V. parahaemolyticus possibly switch from free-living virulent planktonic phenotype to a non-virulent biofilm phenotype, as demonstrated by a decreased transcription of flagella-related motility genes (flaA, CheR, and fliS), Pir toxin (PirB VP), and AHPND plasmid genes (ORF14) and increased expression of the phenotype switching marker AlkPhoX gene in both in vitro and in vivo conditions. Taken together, results suggest that biofloc steer phenotype switching, contributing to the decreased virulence of V. parahaemolyticus AHPND strain toward shrimp postlarvae. This information reinforces our understanding about AHPND in a biofloc setting and opens the possibility to combat AHPND not only by trying to eliminate the AHPND-causing V. parahaemolyticus from the system but rather to steer the phenotypic switch.

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“…2018a, 2018b; Hostins et al. ). Studies have demonstrated that the addition of a carbon source effectively facilitated the growth of whiteleg shrimp.…”

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confidence: 99%

Effects of Addition of Sucrose and Probiotics on Whiteleg Shrimp Litopenaeus vannamei Postlarvae Performance, Water Quality, and Microbial Community

et al. 2019

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It has been reported that supplying a carbon source and probiotics improves water quality and animals in aquaculture systems. Most studies used molasses as a carbon source, which is a mixture of carbohydrate, fat, and protein. In the present study, sucrose and probiotics (Bacillus licheniformis; hereafter referred to by only the genus name “Bacillus”) were added in the culture media of 5‐d‐old postlarvae of whiteleg shrimp Litopenaeus vannamei and then cultured for 20 d. The results showed that compared with the control concentrations of NH4+‐N, NO2−‐N, and NO3−‐N, values were lower in treatments with sucrose and Bacillus, suggesting that water quality was improved and material circulation was promoted. Values of dissolved oxygen decreased, probably due to oxygen consumption during microbial growth and oxidation processes. Body length growth rate of whiteleg shrimp was significantly higher in treatments with sucrose and Bacillus compared with the control, which might result from an increased energy uptake from ingesting microorganisms. In comparison to the control, treatments with sucrose and Bacillus greatly influenced bacterial community structure. Among them, the proportion of Actinobacteria increased and that of Proteobacteria decreased. Actinomycetes can degrade organic compounds and produce a wide variety of antibiotics, vitamins, and enzymes, inhibiting growth of some pathogenic microorganisms. Proteobacteria includes many pathogenic bacteria. Changes in these two phyla suggest that the immunity of whiteleg shrimp might be enhanced in response to treatments. These results indicate that microorganism composition might be important to biofloc systems. Further investigations in this area would help guide aquaculture production.

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Managing input C/N ratio to reduce the risk of Acute Hepatopancreatic Necrosis Disease (AHPND) outbreaks in biofloc systems – A laboratory study

Cited by 47 publications

References 44 publications

Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Biofloc-Based Enhanced Survival of Litopenaeus vannamei Upon AHPND-Causing Vibrio parahaemolyticus Challenge Is Partially Mediated by Reduced Expression of Its Virulence Genes

Effects of Addition of Sucrose and Probiotics on Whiteleg Shrimp Litopenaeus vannamei Postlarvae Performance, Water Quality, and Microbial Community

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