The carbohydrase activity of Aeromonas hydrophila on 25 carbohydrate substrates was examined for: acid production, gas production, hydrolysis, oxidation, and degradation. Quantitative evaluations included zone ratio(R), rate of substrate degradation, and quantity of substrate by-products produced. All 164 A. hydrophila complex strains produced acid from fructose, galactose, maltose, mannitol, trehalose, dextrin, and glycogen; 99.4% of the strains produced acid from glucose, 98.8% from mannose, and 98.2% from glycerol. Acid production from other carbohydrates(arabinose, salicin, cellobiose, sucrose, and lactose)varied. Acid production from cellobiose and lactose was slow and weak, implying a catabolitic repression. Reactions of gas production from carbohydrates were intercorrelated, and correlated positively with gas production from formic acid. Gas production from glucose was observed in 86.6% of the strains. Gas production from other carbohydrates was observed in fewer percent. In polysaccharide utilization tests, starch and chitin were hydrolyzed by 100% and 96.3% of the strains, respectively; No strains utilized algin, pectin, or cellulose; chondrointin sulfate and hyaluronic acid were degraded by 5.5% of the strains, suggesting a chondroitinase similar to that of Proteus or Elavobacteria. Other carbohydrase reactions included esculin hydrolysis, 85.9%; gluconic acid oxidation, 78.0%; and ONPG hydrolysis, 97.5%. Correlation and Chi-square independence analysis indicated relationships among these carbohydrase reactions and showed that carbohydrase reactions were associated with isolate origin.
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