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ENZYMES OF GLYCOLYTIC PATHWAYS IN BACTERIAL PATHOGENS OF SUGARCANE IN INDIA.
ENZYMES OF GLYCOLYTIC PATHWAYS IN BACTERIAL PATHOGENS OF SUGARCANE IN INDIA. NARAYAN C. MANDAL and PRIYABRATA SARKAR Department of Botany, Visva-Bharati, Santiniketan - 731235, India. Background and Objectives Although sugarcane is an important and commercial crop in India, its pathological studies has not gained importance significantly. The present paper attempts to study the metabolic behaviour of bacterial and fungal pathogens of sugarcane in presence of different carbon sources. Materials and Methods Enzymes of glycolytic pathways, tricarboxylic acid cycle and glyoxylate pathway were assayed from cell free extracts of ten strains of bacterial and ten strains of fungal pathogens of sugarcanes after growing their in vitro in different carbon sources. Bacterial strains were belonged to Xanthomonas albilineans causing leaf scald disease, Pseudomonas rubrilineans causing red stripe disease and Pseudomonas rubrilineans pv. spindulifoliens causing spindle rot disease and the fungal strains were belonged to Colletotrichum fascatum causing red rot, Fusarium auriculiformis causing wilt disease, Peronosclerospora sacchari causing downy mildew and Ustilago scitaminea causing whip smut disease of sugarcane respectively. Enzymes were assayed following published procedures of Mandal and Chakrabartty [1] and Mc Fadden [2]. Results and Conclusions Of the giycolytic pathways Embden Meyerhof Pamas and Pentose phosphate pathways are available to all the strains of bacterial as well as fungal pathogens as evidenced by high specific activity of the key enzymes (phosphofructokinase and 6-phosphogluconate dehydrogenase) in the cell free extracts of midlog cultures of these organisms grown in presence of glucose, galactose or sucrose in media. Key enzymes of Entner-Doudoroff pathway were detected only from CFE of cultures of bacterial strains as well as their isolates direct from the infected materials and were not detected from any of the fungal isolates. This enzymatic proparly of the bacterial isolates can be utilized for diagnostic purpose during isolation of a bacterial pathogens. Substantial activity of isocitrate dehydrogenase in all the strain of bacterial and fungal pathogens indicated a constitutive operation of tricarbonylic acid cycle in these organisms. All the bacterial as well as fungal isolates exhibited activity of isocitrate lyase, a key enzyme of glyoxylate pathway when grown in culture media with acetate as the sole source of carbon. But the other carbon sources tested viz., glucose, galactose or sucrose were failed to induce the activity of isocitrate lyase. This indicates the inducible nature of isocitrate lyase in sugarcane pathogens. References 1. Mandal, N.C. and Chakrabartty, P.K. (1993). Curr. Microbiol. 26: 247-251. 2. Mc Fadden, B.A. (1969). Methods Enzymol. 13: 163.