Off-flavour taint of aquaculture products is a global issue reducing consumer confidence in the farmed produce as they are taken up via the gills of fish,and deposited in the lipids of the animal.If the fish are not p...Off-flavour taint of aquaculture products is a global issue reducing consumer confidence in the farmed produce as they are taken up via the gills of fish,and deposited in the lipids of the animal.If the fish are not purged,resulting undesirable muddy earthy flavour taint can be tasted by consumers.These undesirable flavour and odour is caused by the terpenoid compounds namely geosmin and 2-methylisoborneol,produced as secondary metabolites by certain bacteria including the cyanobacteria and actinomycetes.Current strategies to remediate the problem rely on treating the symptoms not the cause and involve the use of time consuming purging methods and costly chemicals.Biological control using bacteriophages,specific to the problem causing bacteria,offers a natural alternative to chemical control,which might reduce further complications of copper based algaecides and its subsequent implications on water quality.In an adaptation of such biological control approach streptomycetes isolated from barramundi ponds were tested for their susceptibility to streptophages to understand whether host destruction via phage lysis would subsequently eliminate off-flavour taint productions by these isolates.Following the determination of the streptophage susceptibility of the isolates one of the most odourous streptomycete species(USC-14510)was selected to be tested further using different pond simulations resembling real-life applications.Geosmin was tested as the indicator of off-flavour taint production and as it has been previously reported that the cyanobacteria-actinomycete interactions occurring in ponds result in even greater levels of geosmin and 2-methylisoborneol,the geosmin levels for the isolate in the presence of cyanobacteria and streptophages were also tested.Findings indicated that the highly odourous Streptomyces species(USC-14510)once infected with streptophages,can lose its capacity to produce off-flavour taints.Pond simulation studies also revealed geosmin production was significantly reduced when streptophages were introduced into the pond water where streptomycete species were grown.The bacteriophage control method developed in the presented study might again confirm significant potential for the bacteriophage-mediated remediation strategy to be adapted by the aquaculture industry.展开更多
Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from ea...Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from each location) were manually segmented to extract the fish-body area (S in cm2), excluding all fins. After scaling the segmented images to 1mm per pixel, the fish mass values (M in grams) were fitted by a single-factor model (M=aS1.5, a=0.1695 )achieving the coefficient of determination (R2) and the Mean Absolute Relative Error (MARE) of R2=0.9819 and MARE=5.1%, respectively. A segmentation Convolutional Neural Network (CNN) was trained on the 200 hand-segmented images, and then applied to the rest of the available images. The CNN predicted fish-body areas were used to fit the mass-area estimation models: the single-factor model, M=aS1.5, a=0.170, R2=0.9819, MARE=5.1%;and the two-factor model, M= aSb, a=0.124, b=0.155, R2=0.9834, MARE=4.5%.展开更多
Asian seabass(Lates calcarifer)is an important foodfish species.It has been cultured in Singapore since the 1980s.A selective breeding program to improve growth,meat quality and disease resistance has been ongoing in ...Asian seabass(Lates calcarifer)is an important foodfish species.It has been cultured in Singapore since the 1980s.A selective breeding program to improve growth,meat quality and disease resistance has been ongoing in Singapore since 2004.In 2012,outbreaks of the big belly disease(BBD)occurred in two batches of offspring generated by a mass-cross among F1 brooders in a hatchery.After the outbreaks,only 437 survived in 6000 F2 juveniles.Molecular parentage analysis with 10 microsatellites revealed that four parents(F1)produced high percentage of offspring that survived the BBD outbreaks.Eighty-two BBD survivor offspring(F2)were selected based on their growth performance at 90 days post hatch(dph),family origin and allelic diversity.They were used as brooders to generate F3.In a period of five years,these F2 brooders produced six batches of offspring,where no outbreak of BBD occurred.In the same period,outbreaks of BBD occurred in 4 out of 18 batches produced by F2 brooders selected for growth,with mortality rates ranging from 85.1%to 95.4%.In F3,the average body weight(57.1±1.09 g,n=3068)of the line for BBD survival was slightly lower than that(60.6±2.29 g,n=4280)of the line for growth at 90 dph.In both lines,the body weight of F3 was much higher than that(46.90±0.19 g,n=12117)of F2.The genetic diversity in the line for BBD survival(F3)was much lower than that in F3 line for growth due to small founder population.These data indicate that the selection of BBD survival during BBD outbreaks using molecular parentage analysis is effective to reduce BBD outbreaks.Avoiding further reduction of genetic diversity is essential in the line selected for increased survival against BBD.展开更多
文摘Off-flavour taint of aquaculture products is a global issue reducing consumer confidence in the farmed produce as they are taken up via the gills of fish,and deposited in the lipids of the animal.If the fish are not purged,resulting undesirable muddy earthy flavour taint can be tasted by consumers.These undesirable flavour and odour is caused by the terpenoid compounds namely geosmin and 2-methylisoborneol,produced as secondary metabolites by certain bacteria including the cyanobacteria and actinomycetes.Current strategies to remediate the problem rely on treating the symptoms not the cause and involve the use of time consuming purging methods and costly chemicals.Biological control using bacteriophages,specific to the problem causing bacteria,offers a natural alternative to chemical control,which might reduce further complications of copper based algaecides and its subsequent implications on water quality.In an adaptation of such biological control approach streptomycetes isolated from barramundi ponds were tested for their susceptibility to streptophages to understand whether host destruction via phage lysis would subsequently eliminate off-flavour taint productions by these isolates.Following the determination of the streptophage susceptibility of the isolates one of the most odourous streptomycete species(USC-14510)was selected to be tested further using different pond simulations resembling real-life applications.Geosmin was tested as the indicator of off-flavour taint production and as it has been previously reported that the cyanobacteria-actinomycete interactions occurring in ponds result in even greater levels of geosmin and 2-methylisoborneol,the geosmin levels for the isolate in the presence of cyanobacteria and streptophages were also tested.Findings indicated that the highly odourous Streptomyces species(USC-14510)once infected with streptophages,can lose its capacity to produce off-flavour taints.Pond simulation studies also revealed geosmin production was significantly reduced when streptophages were introduced into the pond water where streptomycete species were grown.The bacteriophage control method developed in the presented study might again confirm significant potential for the bacteriophage-mediated remediation strategy to be adapted by the aquaculture industry.
文摘Total of 1072 Asian seabass or barramundi (Lates calcarifer) were harvested at two different locations in Queensland, Australia. Each fish was digitally photographed and weighed. A subsample of 200 images (100 from each location) were manually segmented to extract the fish-body area (S in cm2), excluding all fins. After scaling the segmented images to 1mm per pixel, the fish mass values (M in grams) were fitted by a single-factor model (M=aS1.5, a=0.1695 )achieving the coefficient of determination (R2) and the Mean Absolute Relative Error (MARE) of R2=0.9819 and MARE=5.1%, respectively. A segmentation Convolutional Neural Network (CNN) was trained on the 200 hand-segmented images, and then applied to the rest of the available images. The CNN predicted fish-body areas were used to fit the mass-area estimation models: the single-factor model, M=aS1.5, a=0.170, R2=0.9819, MARE=5.1%;and the two-factor model, M= aSb, a=0.124, b=0.155, R2=0.9834, MARE=4.5%.
文摘Asian seabass(Lates calcarifer)is an important foodfish species.It has been cultured in Singapore since the 1980s.A selective breeding program to improve growth,meat quality and disease resistance has been ongoing in Singapore since 2004.In 2012,outbreaks of the big belly disease(BBD)occurred in two batches of offspring generated by a mass-cross among F1 brooders in a hatchery.After the outbreaks,only 437 survived in 6000 F2 juveniles.Molecular parentage analysis with 10 microsatellites revealed that four parents(F1)produced high percentage of offspring that survived the BBD outbreaks.Eighty-two BBD survivor offspring(F2)were selected based on their growth performance at 90 days post hatch(dph),family origin and allelic diversity.They were used as brooders to generate F3.In a period of five years,these F2 brooders produced six batches of offspring,where no outbreak of BBD occurred.In the same period,outbreaks of BBD occurred in 4 out of 18 batches produced by F2 brooders selected for growth,with mortality rates ranging from 85.1%to 95.4%.In F3,the average body weight(57.1±1.09 g,n=3068)of the line for BBD survival was slightly lower than that(60.6±2.29 g,n=4280)of the line for growth at 90 dph.In both lines,the body weight of F3 was much higher than that(46.90±0.19 g,n=12117)of F2.The genetic diversity in the line for BBD survival(F3)was much lower than that in F3 line for growth due to small founder population.These data indicate that the selection of BBD survival during BBD outbreaks using molecular parentage analysis is effective to reduce BBD outbreaks.Avoiding further reduction of genetic diversity is essential in the line selected for increased survival against BBD.
