Analysis of feeding mechanism in a pitcher ofNepenthes hybrida
The process of digestion of captured feeds in a pitcher, an insect-trapping organ, ofNepenthes was studied. Changes in bacterial population, pH and NH4+ concentrations in pitcher juice were examined. Strong activities of both acid- and alkaline phosphatase, phosphoamidase, esterase C4 and esterase C8 were found in the pitcher juice. Optimum pH of proteases in the juice and those secreted from bacteria showed pH 3.0 and pH 8.0–9.0, respectively. Twenty six strains of bacteria were isolated from 4 pitchers: 10 strains were gram positive, 16 strains were gram negative (10 strains had casein hydrolase activity). A proton excretion was induced by NH4+ released from the added solutions, and accordingly, the pH of the solutions fell. As a simulation model of the digestion process of feeds in pitcher juice and polypeptone solution was added into the washed pitcher. A good correlation was found among the NH4+ concentration, pH and bacterial cell titer.
Key wordsBacterial titer Feeding mechanism Nepenthes Pitcher juice Proteases
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