A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used i...A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used include a regulatory protein gene （merR） along with operator/promoter （O/P） derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg（Ⅱ） ions in the concentration range of 100–1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different （P 0.05） for each concentration of inducing Hg（Ⅱ） ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg（Ⅱ） in water samples.展开更多
Changes in protein quality during ice storage affects the muscle structure,the textural quality,functional properties and the eating quality.Dynamic viscoelastic behaviour and gelling properties ofmeat proteinsin rela...Changes in protein quality during ice storage affects the muscle structure,the textural quality,functional properties and the eating quality.Dynamic viscoelastic behaviour and gelling properties ofmeat proteinsin relation to histological changes in white leg shrimp muscles were assessed for 14 days in ice storage.Reduction in Ca2+ATPase activity of fresh myofibrillar protein(MFP),fading of myosin banding pattern and increased gapping in myofibrils were clearly observed with progress of storage.The quality indices of the shrimp muscle were well correlated with histological and functional properties as a function of ice storage.Solubility of fresh MFP was 86.76%which decreased to 77.06%on the 14th day of storage period.Emulsion capacity found to increase during storage period.Gel strength of white leg shrimp meat was low(81±14 g cm)and further,reduced nearly 60%compared to fresh sample at the end of storage.The considerable reductions(from 535.77 kPa to 246.56 kPa)in storage modulus values were evident of diminishing elasticity and gelling ability of the meat due to ice storage.Therefore,this study usherd that the histological deterioration in myofibrils may be used as an indication of diminishing biochemical quality and gelling behaviour of the proteins.展开更多
Effect of ethanol extracts of green tea(Camellia sinensis L.)and amla(Phyllanthus emblica Linn)were investigated on quality and melanosis of chilled stored Indian white prawn(Fenneropenaeus indicus)during 28 days.Extr...Effect of ethanol extracts of green tea(Camellia sinensis L.)and amla(Phyllanthus emblica Linn)were investigated on quality and melanosis of chilled stored Indian white prawn(Fenneropenaeus indicus)during 28 days.Extracts were subjected to antioxidant assays viz.1,1-diphenyl-2-picryl hydrazyl radical reducing power methods(DPPH),total antioxidant capacity(TAC),total phenolic content(TPC)and ferric reducing antioxidant power(FRAP)to evaluate antioxidant potentiality and fourier-transform infrared spectroscopy(FT-IR)to identify organic constituents.Polyphenol oxidase(PPO)inhibition was assessed to check the efficacy of the extracts as anti-melanogenic agents.Biochemical(total volatile nitrogen,free fatty acid and peroxide values),bacteriological(aerobic counts),melanosis inhibition and sensory quality of chilled stored shrimp were addressed to investigate the efficacy of extracts as preservative and anti-melanogenic remedy.Free reducing power of green tea-and amla extracts were in a range of 28.72-65.67%and 17.38-66.95%,respectively.Phenolic content level was almost same for green tea and amla extract(2.46±0.002 and 2.51±0.036 mg GAE/gram).Total antioxidant capacity of green tea(210.33±4.63 mg EqAsc/g)was slightly higher than that of amla extracts(145.56±1.98 mg EqAsc/g).FRAP value revealed that green tea(477.49±3.25 mgE Fe(II)/g)had more ferric reducing power than amla(324.39±5.85 mgE Fe(II)/g).FT-IR analysis revealed the presence of essential organic bioactive compounds,which play an important role in reducing lipid oxidation and quality loss,and both extracts possess an encouraging PPO inhibition ability.Treatment by green tea-and amla extracts on chilled stored shrimp showed promising effects on biochemical and microbiological parameters followed by melanosis inhibition and enhanced sensory attributes.Treated Indian white prawn with green tea-and amla extract revealed significantly(P<0.05)lower value of biochemical indices and microbial load during chilled storage compared to untreated sample.展开更多
基金Director, Central Institute of Fisheries Education, Mumbaifor providing facility and financial assistance in the form of Masters’ Fellowship during the research period
文摘A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λ phage. The genetic elements used include a regulatory protein gene （merR） along with operator/promoter （O/P） derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg（Ⅱ） ions in the concentration range of 100–1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different （P 0.05） for each concentration of inducing Hg（Ⅱ） ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg（Ⅱ） in water samples.
文摘Changes in protein quality during ice storage affects the muscle structure,the textural quality,functional properties and the eating quality.Dynamic viscoelastic behaviour and gelling properties ofmeat proteinsin relation to histological changes in white leg shrimp muscles were assessed for 14 days in ice storage.Reduction in Ca2+ATPase activity of fresh myofibrillar protein(MFP),fading of myosin banding pattern and increased gapping in myofibrils were clearly observed with progress of storage.The quality indices of the shrimp muscle were well correlated with histological and functional properties as a function of ice storage.Solubility of fresh MFP was 86.76%which decreased to 77.06%on the 14th day of storage period.Emulsion capacity found to increase during storage period.Gel strength of white leg shrimp meat was low(81±14 g cm)and further,reduced nearly 60%compared to fresh sample at the end of storage.The considerable reductions(from 535.77 kPa to 246.56 kPa)in storage modulus values were evident of diminishing elasticity and gelling ability of the meat due to ice storage.Therefore,this study usherd that the histological deterioration in myofibrils may be used as an indication of diminishing biochemical quality and gelling behaviour of the proteins.
文摘Effect of ethanol extracts of green tea(Camellia sinensis L.)and amla(Phyllanthus emblica Linn)were investigated on quality and melanosis of chilled stored Indian white prawn(Fenneropenaeus indicus)during 28 days.Extracts were subjected to antioxidant assays viz.1,1-diphenyl-2-picryl hydrazyl radical reducing power methods(DPPH),total antioxidant capacity(TAC),total phenolic content(TPC)and ferric reducing antioxidant power(FRAP)to evaluate antioxidant potentiality and fourier-transform infrared spectroscopy(FT-IR)to identify organic constituents.Polyphenol oxidase(PPO)inhibition was assessed to check the efficacy of the extracts as anti-melanogenic agents.Biochemical(total volatile nitrogen,free fatty acid and peroxide values),bacteriological(aerobic counts),melanosis inhibition and sensory quality of chilled stored shrimp were addressed to investigate the efficacy of extracts as preservative and anti-melanogenic remedy.Free reducing power of green tea-and amla extracts were in a range of 28.72-65.67%and 17.38-66.95%,respectively.Phenolic content level was almost same for green tea and amla extract(2.46±0.002 and 2.51±0.036 mg GAE/gram).Total antioxidant capacity of green tea(210.33±4.63 mg EqAsc/g)was slightly higher than that of amla extracts(145.56±1.98 mg EqAsc/g).FRAP value revealed that green tea(477.49±3.25 mgE Fe(II)/g)had more ferric reducing power than amla(324.39±5.85 mgE Fe(II)/g).FT-IR analysis revealed the presence of essential organic bioactive compounds,which play an important role in reducing lipid oxidation and quality loss,and both extracts possess an encouraging PPO inhibition ability.Treatment by green tea-and amla extracts on chilled stored shrimp showed promising effects on biochemical and microbiological parameters followed by melanosis inhibition and enhanced sensory attributes.Treated Indian white prawn with green tea-and amla extract revealed significantly(P<0.05)lower value of biochemical indices and microbial load during chilled storage compared to untreated sample.
