DR. AGNIHOTRUDU MEMORIAL LECTURE-ARE THERMOPHILIC MOULDS NATURE-BORNE BIOTECHNOLOGISTS? T. Satyanarayana, Dept. of Microbiology, Univ. Of Delhi

36th Ann. Meeting of MSI & Nat. Seminar on Fungal Biodiversity & Bioprospecting….. Goa, India Oct., 29-30, 2009

DR. AGNIHOTRUDU MEMORIAL LECTURE

ARE THERMOPHILIC MOULDS NATURE-BORNE BIOTECHNOLOGISTS?

T. Satyanarayana
Department of Microbiology, University of Delhi South campus, New Delhi 110 021

Thermophilic moulds that are capable of optimal growth at or beyond 40C occur abundantly in soils, decomposing agricultural and forest residues, manures and composts. The biotechnological potential of these moulds stems from their ability to degrade organic matter acting as biodegradants and natural scavengers, to produce an array of industrially important extracellular as well as cell-bound enzymes and antibiotics, in the production of SCP and enriched feeds, and their suitability as agents of bioconversions and experimental systems for genetic manipulations. As a result of their multifarious potential applications, thermophilic moulds appear to be nature-borne biotechnologists. In this lecture, our work on the potential applications of thermophilic moulds will be presented briefly.
These moulds have been shown to play an important role in composting of paddy straw with a high colonizing ability and by secreting polysaccharide-degrading enzymes. Malbranchea pulchella var. sulfurea, Sporotrichum thermophile and Humicola lanuginosa produced xylanases for efficiently saccharifying hemicelluloses present in plant materials. In M. pulchella var. sulfurea, xylose is metabolized through xylose reductase and xylitol reductase as well as xylose isomerase. Acidic pectinases of S. thermophile have been shown to be useful in the extraction of juices from fruit pulps.
Sporotrichum thermophile produces phytase in solid state and submerged fermentations, and also by alginate-immobilized conidiospores. The purified phytase is a homopentameric glycoprotein with a molecular mass of 456 kD, and it is optimally active at pH 5.0 and 60°C with a T1/2 of 16 h at 60°C and 90 min at 80°C. It is insensitive to trypsin and pepsin, and unaffected by EDTA. The enzyme inhibition by 2, 3-butanedione suggested arginine to play a role in catalysis as in other known phytases. The enzyme efficiently degraded phytic acid from sesame oil cake, wheat flour and soymilk. It also promoted the growth of wheat seedlings, and hydrolyzed insoluble calcium, magnesium, iron and cobalt phytates to a varied extent. The supplementation of bread with phytase led to reduction of the anti-nutrient phytic acid. The enzyme has all the requisite properties for its application as a feed and food additive, and dephytinization of soymilk, wheat flour and sesame oil cake. Neutral glucoamylase of Thermomucor indicae-seudaticae hydrolyzed both soluble and raw starches into glucose. The inhibition of enzyme activity by n-bromosuccinimide suggested tryptophan to play a critical role in catalysis. It was found to be suitable in developing an ideal starch saccharification process along with thermostable alpha-amylase and amylopullulanase produced by the extremely thermophilic bacterial strains of Geobacillus thermoleovorans. The supplementation of bread and doughnut formulations with the enzyme led to improvement in loaf volume and shelf life.