This study aimed to evaluate the influence of microalgae addition on the physical and functionality of bioflocs and the growth and health performance of giant prawn (Macrobrachium rosenbergii). Three ...biofloc‐based giant prawn culture systems were compared that is biofloc system without microalgae addition as a control, biofloc system with Chlorella sp. addition and biofloc system with Ankistrodesmus sp. addition. Giant prawn juveniles (2.00 ± 0.10 g) were randomly distributed into 12 units of outdoor fibre tanks (500 L in capacity) at a density of 40 juvenile per tank and maintained for 60 days. Molasses was added at an estimated C/N ratio of 6, and each microalga was added once a week at a density of about 105 cell/mL. The addition of microalgae in biofloc systems did not affect the prawn's survival and immune parameters as well as its robustness against hypoxia stress (p > 0.05). Alkalinity in the microalgae‐added biofloc systems was significantly higher (p < 0.05) than that of the control, whereas total ammonia nitrogen (TAN), nitrite, nitrate, total phosphate and dissolved phosphate were not significantly different amongst the treatments. The addition of Chlorella sp. and Ankistrodesmus sp. resulted in 11% and 18% higher size of biofloc particles, respectively, and altered the fatty acid profile of bioflocs, but did not affect the protein content. In conclusion, Chlorella sp. and Ankistrodesmus sp. addition could increase the particle size and alter the fatty acid profile of bioflocs, but did not affect the water quality and the growth performance of giant prawn in biofloc systems.
The blue mussel (Mytilus edulis) is known as a robust bivalve species, although its larviculture appears to be highly susceptible to diseases. In this study, we isolated 17 strains from induced ...mortality events in healthy wild-caught blue mussel adults and demonstrated that they caused between 17% and 98% mortality in blue mussel larvae in a newly developed, highly controlled immersion challenge test model. Eight of the isolates belong to the Splendidus clade of vibrios, while the other isolates belong to the genus Photobacterium. The genomes of the most virulent Vibrio isolate and the most virulent Photobacterium isolate were sequenced and contained several genes encoding factors that have previously been linked to virulence towards bivalves. In vitro tests confirmed that all 17 isolates were positive for these virulence factors. The sequenced genomes also contained a remarkably high number of multidrug resistance genes. We therefore assessed the sensitivity of all isolates to a broad range of antibiotics and found that there were indeed many strong positive correlations between the sensitivities of the isolates to different antibiotics. Our data provide an ecological insight into mass mortality in blue mussels as they indicate that wild mussels contain a reservoir of pathogenic bacteria.
The packaging of abalone (
H. squamata
) (39.65 ± 0.24 mm TL) for long-term transportation (>8 hours) requires the addition of substances that provide an anesthetic effect so that it could reduce ...stress and maintain survival rate post transportation without having to repack. The objective was to investigate the expression pattern of HSP70 and HSP90 genes of abalone during transport with the addition of 2-phenoxyethanol. Abalone was packed using a styrofoam box with dimensions (42.5 x 75.5 x 27.5 cm3), containing 2 pcs of 10L Polyethylene (PE) plastic bags. The plastic bag consisted of 2 pcs of 25cm, 4-inch Polyvinyl Chloride (PVC) pipe for abalone attached. Both ends line enclosed with screen net and tied with rubber bands. Abalone density was 50 heads/pipe. Transportation tests were carried out using a dry system and wet system with and without the addition of 2-phenoxyethanol (PK, KK). Data analysis was done by paired sample ttest and ANOVA with a 95% confidence interval. The results showed that the best abalone survival (85%) was obtained in wet transport + 2-phenoxyethanol (PB) (
p
<0.05) within 24 hours of transportation.
This study aimed to evaluate and unveil the positive impact of biofloc culture on Vibrio parahaemolyticus infection of Pacific white shrimp by reducing quorum sensing (QS) and virulence gene ...expression and enhancing shrimp's immunity. The shrimp with an average body weight of 0.50 ± 0.09 g were reared in containers with a volume of 2.5 L, 21 units, and a density of 20 shrimp L
. The shrimp were cultured for 5 days, with each treatment including biofloc system maintenance with a C/N ratio of 10 and a control treatment without biofloc, followed by a challenge test through immersion using V. parahaemolyticus at densities of 10
, 10
, and 10
CFU mL
initially. The results of the in vitro experiment showed that biofloc suspension can inhibit and disperse biofilm formation, as well as reduce the exo-enzyme activity (amylase, protease, and chitinase) of V. parahaemolyticus. Furthermore, the biofloc treatment significantly reduced the expression of the QS regulatory gene OpaR, the PirB toxin gene, and the virulence factor genes T6SS1 and T6SS2 in both in vitro and in vivo. The biofloc system also increased the expression of shrimp immunity-related genes (LGBP, proPO, SP, and PE) and the survival rate of white shrimp challenged with V. parahaemolyticus.
Inactivation of quorum sensing (QS) signal molecules, such as acylhomoserine lactones (AHLs) of pathogenic bacteria, has been proposed as a novel method to combat bacterial diseases in aquaculture. ...Despite the importance of micro-algae for aquaculture, AHL degradation by bacteria associated with micro-algal cultures has thus far not been investigated. In this study, we isolated
Pseudomonas
sp. NFMI-T and
Bacillus
sp. NFMI-C from open cultures of the micro-algae
Tetraselmis suecica
and
Chaetoceros muelleri
, respectively. An AHL degradation assay showed that either monocultures or co-cultures of the isolates were able to degrade the AHL
N
-hexanoyl-
l
-homoserine lactone. In contrast, only
Bacillus
sp. NFMI-C was able to inactivate
N
-hydroxybutanoyl-
l
-homoserine lactone, the AHL produced by
Vibrio campbellii
. The isolated bacteria were able to persist for up to 3 weeks in conventionalized micro-algal cultures, indicating that they were able to establish and maintain themselves within open algal cultures. Using gnotobiotic algal cultures, we found that the isolates did not affect growth of the micro-algae from which they were isolated, whereas a mixture of both isolates increased the growth of
Tetraselmis
and decreased the growth of
Chaetoceros
. Finally, addition of
Bacillus
sp. NFMI-C to the rearing water of giant river prawn (
Macrobrachium rosenbergii
) larvae significantly improved survival of the larvae when challenged with pathogenic
V. campbellii
, whereas it had no effect on larval growth.
This research aimed to elucidate the effect of
Chlorella
sp. addition on biofloc quality and growth of
Macrobrachium rosenbergii
juveniles in biofloc systems. Four treatments of freshwater prawn ...nursery culture systems were tested, i.e., control system with clear water system at a regular water exchange at about 50% every 2 weeks; control system with
Chlorella
sp. addition with regular water exchange and weekly addition of
Chlorella
sp.; biofloc system without
Chlorella
sp. addition; and biofloc system with
Chlorella
sp. addition. Freshwater prawn juvenile at an average initial body weight of 0.25 g was randomly distributed into 16 units of aquarium with a working volume of 100 L at a density of 20 prawn/aquarium (50 prawn/m
2
). Molasses was added every day into biofloc treatments at an estimated C/N ratio of 6.25.
Chlorella
sp. was added into the microalgae treatments at the initiation of the experiment and every 2 weeks at 10% of the total volume to reach an estimated final density of about 10
5
/mL. Microbial aggregation was inhibited by vanillin (a quorum sensing inhibitor) addition regardless the presence of
Chlorella
sp. The microalgae addition resulted in biofloc with higher density, larger particle size, and higher protein content. Different amino acid and fatty acid profiles of biofloc were observed between the biofloc treatments. Essential amino acid index of biofloc with the addition of
Chlorella
sp. was about 39% higher compared to that of biofloc without
Chlorella
sp. addition. The growth of freshwater prawn in biofloc systems was generally higher than those of the control with and without
Chlorella
sp. addition. In conclusion, the addition of
Chlorella
sp. could improve biofloc quality and the growth performance of freshwater prawn juveniles.
Vibriosis outbreaks caused by Vibrio harveyi and related species are amongst the major obstacles for the further expansion of giant freshwater prawn (Macrobrachium rosenbergii) larviculture. Vibrio ...harveyi regulates virulence gene expression through quorum sensing, bacterial cell-to-cell communication, and consequently, quorum sensing disruption has been suggested as an alternative strategy to control infections caused by these bacteria. Previous studies have shown that quorum sensing-disrupting compounds are able to disrupt quorum sensing in Vibrio harveyi. In this study, we demonstrated that the quorum sensing-disrupting compounds cinnamaldehyde, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone and (Z)-4-((5-(bromomethylene)-2-oxo-2,5-dihydrothiophen-3-yl)metoxy)-4-oxobutanoic acid increased the survival of giant freshwater prawn larvae when challenged to pathogenic Vibrio harveyi. Our in vivo challenge test showed that cinnamaldehyde and the thiophenone can protect the larvae from Vibrio harveyi infection when dosed to the culture water at 1μM and 10μM, whereas the brominated furanone offered protection at 1μM but resulted in complete mortality at 10μM. Although there were significant differences in survival between challenged larvae with and without addition of quorum sensing-disrupting compounds, there were no differences in growth (as determined by the larval stage index).
•Alternatives to antibiotics to treat bacterial infections in aquaculture are needed.•Quorum sensing regulates virulence of many pathogenic bacteria.•Quorum sensing inhibitors increase survival of prawn larvae challenged to V. harveyi.
The aim of this study was to quantify and identify metabolites of Ice Nucleation Active (INA) bacteria as an anti-biofilm agent against biofilms of fish pathogens such as Aeromonas hydrophila and ...Streptococcus agalactiae. Ice nucleation active bacteria, which have the ability to catalyze ice nucleation, isolated from rainwater in previous studies, were used. All INA isolates were tested in several assays, including the antimicrobial test, which uses streptomycin as the positive control and none of the isolates were found positive in the antimicrobial test. As for the quorum quenching assay, it was found that four out of ten isolates were able to disturb the communication system in Chromobacterium violaceum wild type, which was used as the indicator bacteria. On the next assay, all ten isolates were tested for Biofilm Inhibition and Destruction and showed anti-biofilm activity with the highest percentage inhibition of 33.49% by isolate A40 against A. hydrophila and 77.26% by isolate A19 against S. agalactiae. C1 performed the highest destruction against A. hydrophila and S. agalactiae, with percentages of 32.11% and 51.88%, respectively. As for the GC-MS analysis, supernatants of INA bacteria contain bioactive compounds such as sarcosine and fatty acids, which are known to have antibiofilm activity against several biofilm-forming bacteria. Through 16s rRNA sequencing, identified bacteria are from the Pantoea, Enterobacter, and Acinetobacter genera. As for the conclusion, ice nucleation active bacteria metabolites tested showed positive results against pathogenic bacteria Aeromonas hydrophila and Streptococcus agalactiae in destructing and inhibiting biofilm growth.
This research aims to quantify antiquorum sensing and antibiofilm activity of f phyllosphere bacteria against biofilm formed by pathogenic fish bacteria such as Aeromonas hydrophila, Streptococcus ...agalactiae, and Vibrio harveyi.
Antiquorum sensing assay using Chromobacter violaceum as indicator bacteria and antibiofilm assay showed six phyllosphere bacteria have antiquorum sensing and antibiofilm activities against tested bacteria. The highest inhibition and destruction activity was showed by metabolite of JB 3B and EJB 5 F against A. hydrophila, respectively. Determination using light microscope and scanning electron microscope performed decreaing in biomass of biofilm observed after treated with metabolite from phyllosphere bacteria.
Nutrient supplementations are often added to aquaponic systems to optimize plant production, and black soldier fly larvae frass is a promising organic fertilizer. However, the mineral composition of ...the frass is substantially influenced by the initial substrate. In an 8-week study, sweetpotato slips were cultured at commercial stocking densities in an aquaponic system which received weekly additions of either BSFL frass made from high-nitrogen expired fish diets or low-nitrogen fruits/vegetables. The sweetpotato slips (≥8 nodes) were harvested weekly. Despite differences in the mineral composition between the frass types, the water quality as well as slip production/sugar content were unaffected by frass type. The results indicate that a wide array of substrates may be suitable for producing black soldier fly larvae frass as a fertilizer in aquaponic systems. Lastly, aquaponics is a viable system to commercially produce sweetpotato slips.
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