Influence of feeding habits of fish on the characteristics of their visceral alkaline proteases with special reference to detergent compatibility

Technical characteristics and detergent compatibility of visceral alkaline proteases of three freshwater fish, namely Labeo rohita, Pangasianodon hypophthalmus and Cyprinus carpio of different feeding habits, were studied. Crude enzyme extract was partially purified by (NH₄)₂SO₄ precipitation and dialysis. The molecular weight was in the range of 20–63 kDa. The enzyme purification folds post‐dialysis were found to be 1.55, 1.81 and 2.17 in case of Rohu, Pangas and Common carp respectively. The alkaline protease from Rohu, Pangas and Common carp exhibited maximum activity at pH 10.0, 9.0 and 11.0 respectively. The enzyme temperature optima observed were 60°C (Rohu and Pangas) and 70°C (Common carp). SBTI and EDTA inhibited more than 90% of the activity at conc. of 50 mM. Exposure of the proteases to non‐ionic surfactants like Tween 20–80 retained about 92%–100% and 76%–100% of their activity at conc. (v/v) of 1% and 5% respectively. Proteases were found less stable in the presence of SDS. There was moderate to lesser influence of H₂O₂ and sodium perborate on the proteolytic activity. The alkaline protease from omnivorous fish was found superior compared to the herbivore and carnivore in respect of pH and temperature optima and stability with detergents and oxidizing agents.     

Study of digestive enzyme activities and partial characterization of digestive proteases in a freshwater teleost, Labeo rohita, during early ontogeny

Digestive enzymes of freshwater fish Labeo rohita (family Cyprinidae; class Actinopterygii; infraclass Teleostei; order Cypriniformes) were studied during ontogenic development. Amylase, protease and lipase activities showed a polynomial relationship with age of rohu, whereas trypsin, chymotrypsin and lipase activities exhibited exponential trends with the age of rohu larvae. SDS‐PAGE of crude enzyme extract revealed that the proteases of higher molecular weight (MW) appeared during early ontogeny, whereas low MW proteases were observed at a later stage. Substrate SDS‐PAGE supported the quantitative study of protease activities as evidenced with the increasing number and intensity of activity bands with the age of fish. The number of protease activity bands observed in 4, 10, 12 and 24 DAH (days after hatching) larvae were 5, 7, 8 and 9, respectively. Inhibition of protease activities with soybean trypsin inhibitor (SBTI) (58.6–81.2%), phenyl methyl sulphonyl fluoride (PMSF) (55.6–70%), N‐α‐p‐tosyl‐l ‐lysine chloromethyl ketone (TLCK) (41.1–52.3%) and N‐tosyl‐l ‐phenylalanine chloromethyl ketone (TPCK) (27.9–44.5%) indicated the presence of serine proteases, trypsin‐ and chymotrypsin‐like enzymes in rohu larvae. Inhibition with SBTI and TPCK showed power, TLCK and ethylenediaminetetraacetic acid showed exponential, whereas PMSF showed polynomial relationships during the study period.     

The potential of periphyton-based culture of two Indian major carps, rohu Labeo rohita (Hamilton) and gonia Labeo gonius (Linnaeus)

The effects of periphyton, grown on bamboo substrates, on growth and production of two Indian major carps, rohu, Labeo rohita (Hamilton) and gonia, Labeo gonius (Linnaeus), were studied at the Bangladesh Agricultural University, Mymensingh. For each species, five ponds were provided with bamboo substrates and five ponds without substrate (control). Ponds were stocked at a rate of 10 000 ha^?1 in both treatments. There was no discernible difference in water quality parameters between treatments. A large number of plankton (39 genera) showed periphytic nature and colonized the bamboo substrates. Rohu grew faster, resulting in a 77% higher net production (P < 0.05) in the ponds with bamboo substrates compared with the ponds without substrate. In contrast, the growth and production of gonia did not vary significantly (P > 0.05) between the substrate and control ponds. Rohu seems to be a more suitable candidate for periphyton‐based aquaculture systems than gonia.     

PCR-based segregation of one hybrid variety of Labeo rohita and Catla catla from their wild-types

High consumer preference together with its polyculture potential has undoubtedly driven Rohu (Labeo rohita) and Catla (Catla catla) to top the list of the most preferred fishes among the Indian major carps. Commonly found in these fishes are hybrids that can be natural or man-made. Increasing emphasis on biodiversity issues has necessitated proper stock management of these through molecular genetics techniques. Also with few morphological differences that can be used to differentiate wild types and hybrids properly, the problem demands a straightforward molecular approach. Here, we report a simple PCR-based technique that can differentiate the hybrid variety from wild types easily using three different microsatellite markers. Three sets of primers were used to amplify three different microsatellite markers from the genomic DNA isolated from pectoral fins. When the PCR products using all three primer sets were analyzed, ‘hybrid–Rohu’ could be distinguished from wild types. Whereas the hybrid–Rohu DNA yielded specific PCR products with all three primer pairs, only two PCR products were obtained either from wild-type Catla DNA (by primer sets 1 and 2) or from wild-type Rohu DNA (by primer sets 1 and 3). This study clearly demonstrates that a simple PCR-based technique will help the fish breeders and hatcheries to identify and differentiate suspected hybrid–Rohu carp from the wild types within a few hours.     

In vitro assay of plant protease inhibitors from four different sources on digestive proteases of rohu, Labeo rohita (Hamilton), fingerlings

The in vitro inhibitory effect of protease inhibitors from four seed extracts (soybean, grasspea, black gram and horse gram) on digestive proteases of rohu was assessed by enzyme inhibition assay and substrate sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. High proteolytic activity was detected in the intestinal extract of rohu (Labeo rohita) fingerlings at two different pH ranges (8–8.5 and 10–11). That protein digestion occurs mainly in the alkaline condition in this fish without a stomach is evident from very high trypsin activity (0.95±0.04 benzoyl‐dl ‐arginine‐p‐nitroanilide U mg protein⁻¹) in the intestine. In case of grass pea seed, more than 50% inhibition of alkaline protease activity was recorded when the ratio of inhibitor to enzyme was 9.41 μg U⁻¹. More than 40% inhibition of protease activity was recorded in case of horse gram seed when the ratio of inhibitor to enzyme was 5.51 μg U⁻¹. Black gram at 11.0 μg U⁻¹ and soybean seed proteins at 62.75 μg U⁻¹ resulted in 50% and more than 30% inhibition of digestive protease activity in rohu fingerlings respectively. A plot of the inhibition values obtained by changing the relative concentrations of enzyme/inhibitor resulted in different dose–response curves for different protein sources. The use of substrate gel electrophoresis allowed the visualization of the aforementioned differences in inhibition. Each seed extract produced a characteristic profile of protease inhibition. It is concluded that protease inhibitors present in plant protein sources adversely affect the digestive proteases in fish and hence there is a need to eliminate/reduce the amount of such inhibitors through proper processing before incorporation into aquafeeds.     

Inhibitory effect of <Emphasis Type="Italic">Pistia</Emphasis> tannin on digestive enzymes of Indian major carps: an in vitro study

Aquatic weeds are one of the major unconventional feed ingredients tested for aquafeed formulation. Tannin content in the water lettuce, Pistia, has been quantified (26.67 mg g⁻¹; dry weight) and graded levels of which (12.5–200 μg) have been incorporated in the reaction mixtures to evaluate any change in the in vitro activity of the principal digestive enzymes from the three Indian major carps (IMC), namely rohu (Labeo rohita), catla (Catla catla) and mrigala (Cirrhinus mrigala). Result of the experiment revealed that the Pistia tannin (PT) significantly inhibit/lower the activities of the digestive enzymes from three IMCs in a dose-dependant manner, even at very low concentration. Significant variation in the reduction of the enzyme activities was noticed between the three fish species, as well as between the three enzymes studied. Among the three species studied, digestive enzymes from L. rohita were found to be the most sensitive to the PT, whereas enzymes from C. catla were found to be comparatively least affected. On the other hand, protease and lipase activities were comparatively more affected than the amylase activity. The results of the study suggest that more stress should be given on the elimination of tannin while incorporating feed ingredients of plant origin in fish diets.     

Growth Response and Biochemical Composition of Rohu,Labeo rohita,Fed Salt-Incorporated Diets

Abstract

Rohu, Labeo rohita, fingerlings (av. wt. 1.6 g) were fed pelleted diets supplemented with 0,0.5,1.0,1.5 and 2.0% sodium chloride (NaCl) for 120 days in 25-m³ cement tanks. The final weight gain of fish fed 0.5 and 1.0% NaCl-incorporated diets was significantly (P < 0.05) higher than that of the control (0% NaCl). Net protein retention and carcass protein and fat contents were higher under different treatments as compared to the control. Growth indices and carcass composition indicate inclusion of 1.0% NaCl in the diet to be beneficial for growth promotion in rohu.     

Digestive proteases of three carps Catla catla, Labeo rohita and Hypophthalmichthys molitrix: partial characterization and protein hydrolysis efficiency

Characteristics and functional efficacy of digestive proteases of Catla catla, catla, Labeo rohita, rohu and Hypophthalmichthys molitrix, silver carp were studied. Total protease activity was significantly (P < 0.05) higher in rohu (1.219 ± 0.059 U mg protein⁻¹ min⁻¹) followed by silver carp (1.084 ± 0.061 U mg  protein⁻¹ min⁻¹), and catla (0.193 ± 0.006 U mg  protein⁻¹ min⁻¹). Trypsin activity of silver carp and rohu was 89–91% higher than catla. Chymotrypsin activity was significantly (P < 0.05) higher in silver carp compared with rohu and catla. The protease activity of rohu and silver carp displayed bell‐shaped curves with maximum activity at pH 9; whereas in catla, maximum activity was found between pH 8 and 11. Inhibition of protease activity with soybean trypsin inhibitor (SBTI), phenylmethylsulfonyl fluoride (PMSF) revealed the presence of serine proteases and inhibition of activity with N‐α‐p‐tosyl‐L‐lysine‐chloromethyl ketone (TLCK) and N‐tosyl‐L‐phenylalanychloromethane (TPCK) indicated the presence of trypsin‐like and chymotrypsin‐like enzymes in all these three carps. SDS‐PAGE showed the presence of several protein bands ranging from 15.3 to 121.9 kDa in enzyme extracts of catla, rohu and silver carp. The substrate SDS‐PAGE evidenced the presence of various protease activity bands ranging from 21.6–93.7, 21.6–63.8 and 26.7–98.5 kDa for catla, rohu and silver carp respectively. In pH‐stat hydrolysis of Chilean fishmeal showed significantly (P < 0.05) higher degree of hydrolysis compared with soybean meal, silver cup (a commercial fish feed of Mexico) and wheat flour, with enzyme preparations of three fishes. The rate of hydrolysis was significantly (P < 0.05) higher in silver carp compared with others.     

Phytic Acid‐Induced Inhibition of Digestive Protease and α‐Amylase in Three Indian Major Carps: An in vitro Study

Antinutritional effects of phytic acid (myoinositol hexaphosphate, IP6) on growth and digestibility in fish have been reported. However, specific effect of IP6 on the digestive enzymes in fish has not been addressed. In this study, inhibitory effect of synthetic IP6 (Phytic acid sodium salt, 90% purity) on the activity of the digestive protease and α‐amylase in rohu, Labeo rohita; catla, Catla catla; and mrigal, Cirrhinus mrigala has been investigated in vitro. Graded levels (12.5, 25, 50, 100, 150, and 200 µg/mL) of IP6 were added to the reaction mixtures containing enzyme extracts and substrate solution in triplicate to detect any change in enzyme activity. Results of the experiment revealed that IP6 significantly inhibit/lower activities of the digestive enzymes in a dose‐dependent manner, as evident from the regression equations (F values significant at P < 0.001 level). Apparently, irrespective of the fish species studied IP6‐induced inhibition of α‐amylase activity was greater than protease activity. Among the three fish species studied, C. mrigala appeared to be more sensitive to IP6 for both α‐amylase and protease activity. Enzyme activity was least affected in C. catla. Results of the study might raise concern while incorporating IP6 rich plant‐derived feed ingredients in aqua feed preparation.     

Differential inhibition of digestive proteases by tannin in two size groups of rohu (Labeo rohita,Hamilton): A biochemical and zymography study

This study was intended to evaluate tannin mediated inhibition of digestive proteases in two different size groups (fingerlings, F, 4.5 ± 0.7 cm; advanced fingerlings, AF, 18.2 ± 1.6 cm) of rohu, Labeo rohita. Graded levels (50, 100, 150 and 200 nM) of tannin (Gallotannin, 99% purity) were added to the enzyme extracts (30°C, 1 hr) prior to determination of enzyme activities. Changes in the activity of trypsin, chymotrypsin and total protease in relation to the control sets were determined through biochemical assay of enzymes and SDS‐PAGE zymography. The study revealed that tannin significantly inhibited trypsin, chymotrypsin and total protease activities in a dose dependent manner as evident from the regression equations. The degree of the inhibition appeared to be significantly higher for the F in contrast to the AF (F_5,66 = 282.311; p < 0.0001). Trypsin activities were reduced by 8.04 ± 0.19% to 52.68 ± 0.72% and 5.61 ± 0.22% to 39.46 ± 0.19% in F and AF, respectively. The reduction in Chymotrypsin activities ranged between 16.11 ± 0.03% to 38.02 ± 0.27% in F and 6.31 ± 0.07% to 22.80 ± 0.32% in AF. Total protease activities were reduced by 10.9 ± 0.07% to 49.60 ± 0.32% in L. rohitaF, whereas, it ranged between 5.19 ± 0.06% to 32.60 ± 0.13% in AF. On a comparative scale, the difference in tannin induced inhibition in F and AF were more prominent for trypsin and chymotrypsin than total protease. Further, nine protease activity bands (15.9–69 kD) with different electromobility were noticed in both the size groups. Subsequent densitometry analysis revealed that the average densities of the protease activity bands were gradually decreased with increasing level of tannin exposure (50–200 nM). The study might indicate adaptive tolerance to tannin in larger size groups and emphasizes the need for removal of tannin in the plant feedstuffs, especially for feeding the fingerlings of L. rohita.     

Effects of day and night on swimming,grazing and social behaviours of rohu Labeo rohita (Hamilton) and common carp Cyprinus carpio (L.) in simulated ponds

Diel rhythmicity of grazing, swimming, resting and social interactions of rohu (Labeo rohita) (weight 66.5–68.3 g) and common carp (Cyprinus carpio) (79.9–82.0 g) were observed in 1 m² simulated ponds using video images. Fish behaviour was monitored during a full 24‐h period, starting at 08:00 hours with a 15‐min recording, which was repeated every 3 h. Rohu spent more time grazing during the day than at night. Grazing activity peaked at the beginning and at the end of the day. Grazing and resting of rohu were negatively correlated. Common carp grazed day and night, showing no distinct grazing peak. Considering the grazing time of rohu and common carp, a feeding schedule with two feeding times at 07:30 and 16:30 hours might be appropriate for better food intake and conversion in rohu–common carp polyculture system.     

Purification and characterization of stomach protease from the turbot (Scophthalmus maximus L.)

Proteolytic activity in the different parts of the digestive tract of the turbot (Scophthalmus maximus L.) were studied in this work. One pure protease was isolated from turbot stomach and its behavior was studied. Results showed the optimum pH for proteases in the different parts of the digestive tract of the turbot were pH 2.0 for the stomach, pH 8.0 for the pylorus cecum, pH 8.0 for the foregut, pH 8.5 for the midgut, and pH 8.0 for the hindgut. The activity of proteases in the different parts of the digestive tract were in the sequence pylorus cecum protease > stomach protease > foregut protease > midgut protease > hindgut protease. The stomach protease was purified by ammonium sulfate precipitation and column chromatography on DEAE-Sepharose F.F. and Sephadex G-100. The purified enzyme gave a single band in SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Its molecular weight was found to be approximately 42,000 Da. The enzyme is stable at pH 1.0–9.0 and at temperatures below 40°C. Its activity was maximum at pH 2.0 and 40°C. When reaction time was prolonged the optimum temperature of the enzyme tended to decline. The enzyme was activated by Mn²⁺ and Cu²⁺ and inactivated by Fe³⁺. It was fully inhibited by pepstatin and partially inhibited by PMSF, TPCK, PCMB, and NBS. These results imply the enzyme is a pepsin.     

Identification of gut‐associated amylase,cellulase and protease‐producing bacteria in three species of Indian major carps

Isolation and enumeration of amylase, cellulase and protease‐producing autochthonous bacteria in the proximal intestine (PI) and distal intestine (DI) of three species of Indian major carps, catla (Catla catla), mrigal (Cirrhinus mrigala) and rohu (Labeo rohita), were investigated using the conventional culture‐based technique. Population levels of amylolytic strains were the highest in the PI of catla and the lowest in the DI of rohu. The highest viable count of cellulase and protease‐producing bacteria was recorded in the DI and PI of mrigal respectively. Among the bacteria isolated, 10 strains (five from PI and five from DI) were selected as potent enzyme producers according to a quantitative enzyme assay. The chosen strains were further identified by 16S rRNA gene sequence analysis. The five strains isolated from catla showed high similarity to Citrobacter sp. clone W2, Enterobacter sp. JA24, Bacillus coagulans strain TR, uncultured bacterial clone Hel3bc04 and Bacillus cereus strain UST2006‐BC004. The four strains isolated from mrigal were most closely related to Bacillus sp. KCd2, uncultured bacterial clone Hel3bd09, B. cereus strain BU040901‐020 and Citrobacter freundii strain YRL11, while the strain isolated from rohu probably belonged to Bacillus sp. GV.     

DNA fingerprinting in Indian major carps and tilapia by Bkm 2(8) and M13 probes

DNA fingerprints were obtained in three species of commercially important freshwater fishes, Labeo rohita (Hamilton). Catla catla (Hamilton) and Oreachromis mossambicus (Peters), using Bkm 2(8) and M13 multilocus probes. Bkm 2(8) gave a higher number of bands when compared with M13. However, the number of bands obtained by each probe in O. mossambicus was similar. The higher band-sharing coefficient observed in this species may be attributed to inbreeding as it arose from a small founder population. In L rohita and C. catla, the Bkm 2(8) detected similar DNA fingerprints when two enzymes Hinfi and Taqi were used. The M13 probe also gave similar fingerprints with three restriction enzymes (Hinfi, Taqi, Alui). Comparison of the DNA fingerprints obtained by Bkm 2(8) and Ml 3 showed that these two probes detected different alleles. The overall similarity of the DNA fingerprint patterns in L. rohita and C. catla may be due to their genetic closeness as indicated by their same chromosome number, C-value and their ability to produce fertile hybrids. A similar argument also holds true for the Oreochromis species where interspecies hybridization results in fertile offspring.     

Achyranthes aspera (Prickly chaff flower) leaves- and seeds-supplemented diets regulate growth,innate immunity,and oxidative stress in Aeromonas hydrophila-challenged Labeo rohita

ABSTRACT

The immunostimulatory and disease-resistance properties of Achyranthes aspera were evaluated in rohu (Labeo rohita) challenged with Aeromonas hydrophila. Experimental diets were enriched with leaves at 0.25% (D1) and 0.5% (D2) and seeds at 0.5% (D3); the control diet (D4) was without any enrichment. Rohu (2.02 ± 0.23 g) were cultured for 75 days and then challenged with bacteria. The highest average weight was observed in the D3 diet-fed fish. The cumulative mortality rates were 70%, 60%, 40%, and 30% in the D4, D1, D2, and D3 diets fed to rohu respectively. Enriched diets significantly increased myeloperoxidase, nitric oxide synthase, and serum lysozyme levels and decreased malondialdehyde and carbonyl protein content. Expressions of lysozyme C and lysozyme G were significantly (P < .05) higher in the D3 diet-fed fish. In the kidney, IL-1β and TLR 4 were up-regulated in enriched-diet-fed fish. Supplementation of seeds and leaves at 0.5% showed a positive impact in fish.     

Viscera of Labeo rohita: A Potential Source of Trypsin for Industrial Application

ABSTRACT

The serine protease trypsin was isolated and purified from the digestive system of carp Labeo rohita rohu by ammonium sulphate precipitation, ion exchange, and affinity chromatography. The purified enzyme showed high activity between pH 7.0 and 9.0. The activity was maximum at 40°C. Incubation of the purified enzyme with CaCl₂ (2 mM) stabilized the enzyme activity for 8 h. The enzyme showed stability at 30 and 40°C for 1 h, but above 40°C, enzyme activity was reduced. The kinetic constants were recorded as K_m (0.104 mM), k_cat (44.25 s^?1), and catalytic efficiency (427.54 s^?1 mM^?1). Monovalent, bivalent, and trivalent ions (Li⁺, K⁺, Hg²⁺, Al³⁺, Mg^2+, Cd^2+, Co^2+, Zn²⁺, and Al³⁺) influenced the enzyme activity. Phenylmethylsulfonylflouride, soybean trypsin inhibitor, and N-α-p-tosyl-_L-lysine chloromethyl ketone completely inhibited the enzyme activity, while ethylenediaminetetraacetate caused partial inhibition. Molecular mass of the purified enzyme was 22.46 kDa. The pH and temperature stability of enzyme may be useful for its industrial applications.     

Anaesthetic efficacy of MS‐222 and AQUI‐S® in advanced size fry of rohu,Labeo rohita, (Hamilton‐Buchanan)

Anaesthetic agents are very useful for reducing the stress caused by handling, sorting, transportation, artificial reproduction, tagging, administration of vaccines and surgical procedures in fish. The efficacy of two anaesthetics: MS‐222 and AQUI‐S^® were tested on rohu, Labeo rohita advanced size fry. The lowest effective doses that produced induction in 3 min or less and recovery times 5 min or less and meet the most criteria of good anaesthetic characteristics were 125 mg L^?1 of MS‐222, and 30 mg L^?1 of AQUI‐S^® in rohu, Labeo rohita advanced size fry. Induction times were significantly decreased with increased in the concentrations of any of the two tested anaesthetic agents. The lowest doses suitable for transportation of rohu advanced size fry observed were: 10–15 mg L^?1 of MS‐222 and 2.5 mg L^?1 AQUI‐S^®. Both anaesthetics showed promising to be used as anaesthetics for handling and transportation in rohu (Labeo rohita) advanced fry.     

Fermentative Properties of Proteolytic Pediococcus Strains Isolated from Salt Fermented Fish Hydrolysate Prepared Using Freshwater Fish Rohu (Labeo rohita)

Salt fermented fish hydrolysate (SFFH) was prepared from freshwater fish Rohu (Labeo rohita), an Indian major carp, using salt at room temperature for 50 days. Total lactic acid bacteria (LAB) counts of SFFH prepared using 20% and 30% NaCl (w/w) were found to be in the range of 5.83–7.25 log cfu/ml and 3.93–5.46 log cfu/ml, respectively, whereas the log cfu/ml values for the halotolerant LAB counts varied from 2.09 to 7.17 and 2.02 to 4.77, respectively. Out of 96 isolates from SFFH, 21 isolates were screened based on their pH reducing ability, total titratable acidity, and proteolytic properties. Morphological, biochemical, and molecular characterization of four selected LAB strains were carried out. The isolates FSAP3-3 (Pediococcus pentosaceus), FSBP4-40 (Pediococcus pentosaceus), FSBP16-40 (Pediococcus pentosaceus), and FSBP28-50 (Pediococcus acidilactici) showed both halotolerant and proteolytic properties. The identified LAB isolates showed antagonistic properties against several human pathogens and exhibited sensitivity toward a broad spectrum of antibiotics. All the identified LAB isolates showed excellent proteolytic activity and phosphohydrolase activity. These halotolerant LAB isolates that had both proteolytic properties and acidifying ability have the potential for application in an acceleration of fermentation to produce salted fish products (i.e., fish sauce, fish paste, fish mince, etc.).     

Comparative evaluation of fermented and non-fermented de-oiled rice bran with or without exogenous enzymes supplementation in the diet of <Emphasis Type="Italic">Labeo rohita</Emphasis> (Hamilton, 1822)

A 60-day feeding trial was conducted to study the effect of exogenous enzymes (xylanase and phytase) supplementation in the non-fermented and fermented de-oiled rice bran (DORB)-based diet of Labeo rohita. Four test diets (T1-DORB-based diet, T2-fermented DORB-based diet, T3-phytase and xylanase supplemented DORB-based diet, and T4-phytase and xylanase supplemented fermented DORB-based diet) were formulated and fed to the respective groups. Test diets T3 and T4 were supplemented with 0.01% xylanase (16,000 U kg^?1) and 0.01% phytase (500 U kg^?1) enzymes. One hundred twenty juveniles of L. rohita, with an average weight 5.01?±?0.02 g, were stocked in 12 uniform size plastic rectangular tanks in triplicate with 10 fishes per tank following a completely randomized design (CRD). Exogenous enzyme supplementation to the T3 group significantly improved the growth performance of L. rohita (p?<?0.05). Fermented DORB fed groups registered significantly lower growth irrespective of the supplementation of exogenous enzymes. The carcass composition (except CP %), enzyme activities (except amylase activity), globulin, and A/G ratio did not vary significantly (p?>?0.05). Based on the results of the present study, it is concluded that exogenous enzyme supplementation significantly increases the growth of fish fed with DORB-based diet.     

Golden Grey Mullet (Liza aurata) Alkaline Proteases: Biochemical Characterization,Application in the Shrimp Wastes Deproteinization,Laundry Commercial Detergents,and Preparation of Antioxidant Protein Hydrolysate

Digestive alkaline proteinases from golden grey mullet (Liza aurata) were extracted and characterized. The crude alkaline protease showed optimum activity at pH 8.0 and 60°C, and it was highly stable over a wide range of pH from 4.0 to 10.0, retaining more than 80% activity after incubation for 1 h at 4°C. The alkaline proteases showed extreme stability toward nonionic and anionic surfactants after preincubation for 1 h at 25°C and relative stability toward oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various solid and liquid detergents. Further, proteases from golden grey mullet viscera were found to be effective in the deproteinization of shrimp wastes. The protein removal after 3 h at 45°C with an enzyme/substrate (E/S) ratio of 10 U/mg protein was about 76%. The golden grey mullet proteases were also shown to be efficient in the production of antioxidant protein hydrolysate.