K. C. Dora

Supplementation of prebiotics in fish feed: a review

Aquaculture is one of the fastest growing industries in the world. There is a need for enhanced disease resistance, feed efficiency and growth performance of cultured fish species. The cost of production are likely to be reduced if growth performance and feed efficiency are increased in commercial aquaculture. Also if the survivility of the fishes increase, then their overall production cost would be remarkably reduced. Dietary supplementation of different feed additives e.g. immunostimulants, probiotics and prebiotics usually in small quantities for the purpose of fortifying it with certain nutrients have been found to be beneficial for improving immune status, feed efficiency and growth performance of crustaceans and finfishes. The present article was constructed to highlight the effect of dietary prebiotics on different body growth parameters of fish. However, the application of prebiotics and supplementary enzymes in fish feed is now gradually gaining importance in commercial aquaculture practices, the article stresses on the effect of prebiotics on live body weight gain, dressing percentage, weight of vital organs and muscles and mean villus lengths in digestive tract of fish along with their application as growth promoters in commercial aquafeed (Gatesoupe in Aqua Feeds Formul Beyond 2(3):3–5, 2005; Ganguly et al. in Israeli J Aquac Bamidgeh 62(3):130–138, 2010a, Fish Chimes 30(7):64, 2010b).

Effect of sodium lactate as cryostabilizer on physico-chemical attributes of croaker (Johnius gangeticus) muscle protein.

Effect of sodium lactate as cryostabilizer on physico-chemical attributes of croaker (Johnius gangeticus) fish muscle protein was studied during freezing and frozen (−20 ± 2°C) storage for 3 months. Minced meat was mixed with 4% sucrose, 4% sorbitol, and 0.3% sodium tri poly phosphate (STPP) (T1), minced meat was mixed with 6% (w/v) sodium lactate and 0.3% STPP (T2) and control (C) was without any additive. The decreasing rate of Ca2+ ATPase activity, thaw drip, water holding capacity and relative viscosity in T1 and T2 samples from that of C was significantly lower, indicating higher protective effect of additives. In case of cryoprotectant treated samples, the degradation of myosin heavy chain was much lower than that of C which prevents the aggregation and subsequent insolubilization of myosin during frozen storage. The sodium lactate prevented Ca2+ATPase activity more than that of sucrose/sorbitol during isothermal storage at −20 ± 2°C for 3 months. This inferred that sodium lactate can effectively be used as an alternative cryostabilizer to sucrose/sorbitol for stabilization of croaker muscle protein native structure.

Isolation and Characterization of Bacteriocin Producing Lactobacillus plantarum from Shidal-A Traditional Fermented Fish Product of Assam

Presence of Lactobacillus group of bacteria has long being explored and documented for their presence in different kinds of fermented food products. In the present study, lactic acid bacteria (LAB) were selectively isolated from shidal, a traditional fermented fish product of Assam. Lactobacillus spp. constitutes a diverse group of bacteria widely distributed in the fermented products. In the context, Lactobacillus plantarum was isolated from shidal. The isolate was found to be bacteriocin positive possessing promising antibacterial property.

Efficacy of Biofermenter on Shrimp Head Waste Using Lactobacillus brevis (MTCC 1750)

The shellfish processing industry in India generates about 8.5 million tonnes of waste per year which is rich in protein (40.37±0.74) with excellent amount of amino acid and can effectively be substituted in fish meal for feed preparation. The utilization of available protein in shrimp head meal by fishes is limited due to the presence of crude fibre (chitin). Fermentation can reduce this crude fibre by the breakdown of glycosidic bond between protein and chitin converting the product easily digestible. Fermentation of shrimp head waste in biofermenter reduces the fermentation time substantially as compared to conventional method.

Influence of Chemical Preservatives on the Quality and Shelf-Life of Dried Bombay Duck ( Harpodon nehereus )

Dry fish is the low cost dietary protein source in India. Sometimes dry fishes are kept for a longer period that is the key factor of the deterioration of nutritional value of dry fishes, as they absorb moisture from the surrounding air. In the present study Bombay duck ( Harpodon nehereus ) were treated separately with saturated brine (Control, C), dry salt with 0.25 per cent potassium sorbate ( T 1 ) and saturated brine with 0.3 per cent sodium benzoate (T 2 ) and kept at ambient temperature for storage study after drying in open sun. The general purpose of this study is to determine the proximate composition of dry fishes treated with chemical preservatives and to investigate the quality changes of dried fishes with the increasing of storing period. The values for protein, fat, ash and moisture of dry fish for three different treatments were found in a range of 53.91 to 56.33 per cent, 5.94 to 11.77per cent, 14.78 to 21.96 per cent and 6.9 to 7.42 per cent, respectively. The results of biochemical parameters revealed that during storage period, TVBN, TMA and PV content of T 2 was better than C and T 1 whereas TBA of C was better than T 1 and T 2 . The microbial parameters revealed that the quality of the dry fishes of both the samples (T 1 and T 2 ), treated with preservatives, were of good quality and remain acceptable for longer duration than the control (C). Depending upon the sensory evaluation the overall acceptability of the dried fishes (T 1 , T 2 and C) was significantly declined during storage. The findings of this study showed that nutritional value of dry fishes treated with chemical preservatives give a better storage life than control.

Detection and Characterisation of Antimicrobial Peptide Produced by Bacillus subtilis FPTB23 Isolated from Curd

The growing consumer demand for finding natural but effective food preservation free of potential health risks has stimulated research in the field of biopreservation to find an attractive and alternative approach to chemical preservatives. Among the 51 colonies that displayed antibacterial activity against the indicator lawn of Staphylococcus aureus ATCC 25923, one colony isolated from curd, showed strong antimicrobial activity against the indicators tested, viz., Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (MTCC 2729), Vibrio cholera and Vibrio parahaemolyticus . The isolate was identified as Bacillus subtilis by 16S rRNA gene sequencing and NCBI BLAST Analysis, having the Accession number KF556680. The neutralized cell free supernatant (NCFS) of isolate B. subtilis FPTB23 was able to inhibit the growth of S. aurus (ATCC 25923), E. faecalis (MTCC 2729), V. cholerae and V. parahaemolyticus inferring that the NCFS contains metabolites which is either a bacteriocin or bacteriocin like inhibitory substance. The strong antagonism against a number of serious and challenging foodborne pathogens/spoilage-causing micro-organisms advocated the high possibility of using this isolate as an effective preservative in food. The minimum inhibitory concentration (MIC) for the NCFS of Bacillus subtilis FPTB23 against Enterococcus faecalis (MTCC 2729) was found to be 200 AU/ml. The antimicrobial substance produced by B. subtilis FPTB23 was moderately heat stable, showed maximum activity at pH 7. The NCFS was completely inactivated after treatment with proteolytic enzymes such as, proteinase K and protease, which reveals the proteinaceous nature of the active substance. Exposure to Triton x-100, Tween 80, chloroform and butanol significantly decrease inhibition action. The molecular mass of the active form was found 21.5kDa by SDS-PAGE. The isolated species or its NCFS, therefore, can be used as food preservative reducing the requirement of intense heat treatments for foods to extend the shelf lives, thus, helping to maintain the freshness or unique texture of foods.