Immobilised Phytase Production from Aspergillus foetidus MTCC 11682 Using an Optimized Media

Aim: Immobilised fungal phytase production from the novel strain Aspergillus foetidus MTTC 11682 and optimisation of cultural conditions for a better and continuous economic yield. Study Design: The study was designed based on the classical method of changing one independent variable while fixing all other at a certain level- one factor at a time, a close ended system for the optimisation of fermentation process. Methodology: Physical and nutritional parameters were optimised for phytase production and subjected to statistical analysis. Adsorption and Entrapment techniques were employed to immobilise the production strain. Results: The optimum physical conditions for augmenting the yield up to 6 days incubation period were as follows: pH of 3.5, 30ºC temperatures and 5% inoculum size. Amongst the nutritional parameters, lactose and sodium nitrate were found to be the best carbon and nitrogen sources. K++, Mg++, Mn++ and Fe++ ions supported the phytase production. TritonX 100 and tween 80 showed an inducing effect on the secretion of phytase enzyme. Immobilised fungal phytase production resulted in an increased yield of 32.5% with poly urethane foam (PUF) as the matrix. A scale up fermentation resulted in an activity of 52.7 FTU/mL for immobilised cells as compared to 25.5 FTU/mL by its free counterpart. Conclusion: Phytase produced in an optimised media employing immobilised Aspergillus foetidus 11682 on poly urethane foam cubes exhibited better phytase activity, improved stability and long shelf life.

Value addition of corn husks through enzymatic production of xylooligosaccharides

ABSTRACT Corn husks are the major wastes of corn industries with meagre economic significance. The present study was planned for value addition of corn husk through extraction of xylan, followed by its enzymatic hydrolysis into xylooligosaccharides, a pentose based prebiotic. Compositional analysis of corn husks revealed neutral detergent fibre 68.87%, acid detergent fibre 31.48%, hemicelluloses 37.39%, cellulose 29.07% and crude protein 2.68%. Irrespective of the extraction conditions, sodium hydroxide was found to be more effective in maximizing the yield of xylan from corn husks than potassium hydroxide (84% vs. 66%). Application of xylanase over the xylan of corn husks resulted into production of xylooligosaccharides with different degree of polymerization namely, xylobiose and xylotriose in addition to xylose monomer. On the basis of response surface model analysis, the maximum yield of xylobiose (1.9 mg/ml) was achieved with the enzymatic hydrolysis conditions of pH 5.8, temperature 44°C, enzyme dose 5.7U/ml and hydrolysis time of 17.5h. Therefore, the corn husks could be used as raw material for xylan extraction vis a vis its translation into prebiotic xylooligosaccharides.

Modelling epidemiology of leprosy.

A simulation model for leprosy transmission and control has been developed with specific objectives. Several sensitivity experiments have been carried out by altering the various inputs based on empirical data combined with intelligent guessing. The outputs generated through these exercises were on the expected lines. While incremental exercises would improve the model, it can be used even at the existing stage as a tool for programme managers.

Efficacy of a Bacillus sphaericus formulation as influenced by the quality of Culex quinquefasciatus breeding waters.

To understand the physico-chemical factors that influence the efficacy of B. sphaericus formulation in the breeding sites of Culex quinquefasciatus, a study was carried out in Mayiladuturai area of Tamil Nadu (India). The factors studied were hydrogen ion concentration (pH), acidity, alkalinity, chlorides, phosphates, total hardness, sulphates, total solids, dissolved solids, suspended solids, nitrate nitrogen, ammoniacal nitrogen, dissolved oxygen, biological oxygen demand (BOD) and chemical oxygen demand (COD). Efficacy of the formulation was assessed in terms of reduction in larval population in the treated habitats. pH of water in the treated sites was around neutral range (mean +/- SD 7.65 +/- 0.23). Phosphate content was low (2.27 +/- 1.34 ppm) whereas chlorides (326.1 +/- 55.8 ppm) and sulphates (38.9 +/- 23.8 ppm) were high. Total hardness ranged from 206 to 462.5 ppm with a mean of 312.1 +/- 80.5 ppm. The chlorides and sulphates, though present in considerable quantity, did not have any influence on the efficacy of B. sphaericus formulation. However, the proportion of insoluble chlorides and sulphates which contribute to total hardness seemed to influence the formulation adversely.

Efficacy of Bacillus sphaericus in different breeding habitats of Culex quinquefasciatus.

'Spherifix', an alginate based slow release formulation of Bacillus sphaericus was field tested in different types of breeding habitats of Culex quinquefasciatus at the dose of 15 kg ai/ha at bimonthly interval. The efficacy of the formulation was higher in most of the months except in rainy and post-rainy months. The mean percentage reduction +/-SD during the treatment phase of one year was 31.2 +/- 17.9, 50 +/- 29.4, 28.3 +/- 17.6, 30.3 +/- 21.1, 66 +/- 22.5 and 53 +/- 20.4 in larval density and 49 +/- 20.8, 65.1 +/- 26.1, 30.3 +/- 21.9, 59.8 +/- 22.6, 63.1 +/- 21.9 and 47.7 +/- 24.2 in pupal density respectively in cement tanks, cesspools, cesspits, disused wells, unlined drains and cement lined drains. The reduction in immature density was relatively higher in undisturbed, debris free and shallow habitats such as cesspools, unlined drains and cement lined drains. After withdrawal of treatment, the effect of the formulation could be seen for a period of four months.