Breakdown of chitin by Cytophaga johnsonii

Summary Decomposition of chitin by Cytophaga johnsonii was investigated. Unlike other chitinolytic bacteria, some strains of C. johnsonii did not liberate chitinase extracellularly; instead the cells of such strains had need for close contact with the chitin particles in order to hydrolyze them. The cell-free extract of one of these strains, viz., C. johnsonii C35 did show presence of chitinase. The remaining strains liberated an extracellular chitinase and a chitobiase. The partially purified chitinase from the culture filtrates of C. johnsonii C31 was most active at pH 6.3–6.5 and at 40°C.Metabolism of N-acetylglucosamine, a product of chitin hydrolysis, by C. johnsonii C35 and C31 was investigated. The nature of some of the products formed and the steps involved in their transformations by the resting cells and the cell-free extracts suggested that N-acetylglucosamine first gets deacetylated to glucosamine before it is further oxidized to glucosaminic acid by these strains. Both strains were also able to dehydrogenate gluconate to 2-ketogluconate, the former being in all probability the product of deamination of glucosaminic acid.