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In this experiment, effect of lead (Pb) + chromium (Cr) mixture on superoxide dismutase (SOD) in the liver of Labeo rohita at a concentration of 11.1 mgL-1 was observed. The ammonium sulphate precipitation and ion exchange chromatography techniques were successfully used to purify SOD. After purification, SOD activity of control and Pb+Cr treated fish was noted as 581.00 and 645.45 UmL-1, respectively while the specific activity was 1383.33 and 1613.62 Umg-1, respectively. The fold purification value of SOD was 2.75 and 2.45 for control and stressed fish, respectively. The recovery was calculated as 77.06 and 57.43% for control and stressed fish, respectively. The results of kinetic characterization showed that SOD form control and exposed fish had maximum activity at pH 6.5 and 7.0. Temperature also had a significant effect on activity of SOD. The SOD activity was measured maximum at 30°C for both control and Pb+Cr exposed fish. The Km value of liver SOD for control and Pb+Cr treated L. rohita was calculated as 1.48 and 0.62 mM, respectively. The value of Vmax for SOD from liver of control and Pb+Cr exposed fish was 1000 and 570 U mL-1, respectively. The enthalpy of denaturation (ΔH*) for liver SOD from control and Pb+Cr exposed L. rohita was computed as 3.492 and 2.802 KJ mol-1 at 40°C, respectively and these values were dropped off with increasing the temperature until it remains 3.251 and 2.561 KJ mol-1 at 70°C, respectively. The free energy of thermal denaturation (ΔG°) of liver SOD was slightly increased with increasing temperature until 75°C which shows its resistance against heat. The values of ΔG° was observed as 58.03 and 57.95 KJ mol-1 for control and exposed fish at 40°C, respectively while the same was increased upto 62.37 and 62.00 KJ mol-1 at 70°C, respectively. It was concluded from negative value of ΔS* (entropy of inactivation) that the SOD is stable thermodynamically. [ABSTRACT FROM AUTHOR]

The aim of this research was to isolate lactic acid bacterial (LAB) strains, characterize them and classify the bacteriocin producing LAB strain from indigenous dairy sources. Antimicrobial potential of LAB strain was tested against L. monocytogens. The antimicrobial compound was also tested for maintaining the decreased colony forming unit (CFU) for minimally processed vegetables like carrots, cabbage and lettuce in second phase of the research. The initial identification was based on conventional morphological and biochemical analysis while the final confirmation was done by utilizing advanced molecular tools. Prior to all these manipulations the growth conditions were carefully optimized for the respective strains. The study finally led us to conclude that Lactococcus lactis subsp. lactis was the most abundant type of lactic acid bacteria found in indigenous dairy products (sour cream and cheese) samples studied. A bacteriocin (Lacticin SC07) produced during the growth of Lactococcus lactis subsp. lactis was purified partially by using biochemical technique ammonium sulfate precipitation in different percentages (60% and 80%). These precipitations lead to a 437-fold increase in total lacticin SC07 activity. SDS-PAGE electrophoretic pattern of lacticin showed that it is a single peptide band of 1.7 kDa. But, 3.7 kDa dimers also showing lacticin SC07 activity. The findings of my research revealed that the isolated LAB strain has good potential for bacteriocin production and antimicrobial potential that exerts in the usage of this bacteriocin (lacticinSC07) as a natural preservative in minimally processed vegetable industry. [ABSTRACT FROM AUTHOR]

A study was conducted to purify and characterize a novel protease produced from Aspergillus niger using different lignocellulosic agro-based by-products including corncobs, wheat bran, and rice bran as substrates under SSF. Maximum protease activity was recorded on wheat bran fermented culture media after the 3rd day of incubation. The optimal conditions found for protease production using wheat bran were cultivation period (3 days), substrate concentration (10 g), pH (7), incubation temperature (45°C), inoculum size (4 mL), and 3% surfactant Tween-80 (2 mL). A purification fold of 2.41 with 29 U/mg specific activity and 70.73 % recovery was achieved after purification. Purified protease from A. niger had a molecular weight of 47 kDa on SDS-PAGE. The enzyme activity profile showed that purified protease was optimally active at pH 7 and 45°C as optimum values. A. niger protease was reasonably stable in the pH range 5-8 and 35-60°C for up to 1 h incubation. Protease was activated by various metal ions/inhibitors tested, Mn2+, Cd2+, Mg2+, Cu2+, PMSF, Pepstatin and Iodoacetic acid at 1 mM, proving the enzyme as metalloprotease, whereas an inhibitory effect was shown by certain agents including EDTA and SDS. The purified protease was compatible with five local detergents with up to 25 days of shelf life at room temperature. The maximum production of protease in the presence of a cheaper substrate at low concentration and its potential as a detergent additive for improved washing makes the strain and its enzymes potentially useful for industrial purposes, especially for the detergent and laundry industry. [ABSTRACT FROM AUTHOR]