Studies on the carbohydrate metabolism of the liver fluke Fasciola hepatica

Abstract

Fasciola hepatica utilizes carbohydrate anaerobically at a high rate. When glucose is omitted from the medium, the amount of glycogen utilized varies from 84–97 μmoles of glucose units/g wet wt./6 h. The rate of glucose utilization from the outside medium varies from 110–180 μmoles/g wet wt./6 h. Production of volatile fatty acids accounts for almost all of the carbohydrate utilized anaerobically. These acids were identified as propionic and acetic acids in an approximate ratio of 3:1. Only 4–9% of the metabolized carbohydrate is converted to lactic acid. The rates of glucose utilization, lactic acid and volatile fatty acid production are only slightly decreased in the presence of atmospheric oxygen. Oxygen is utilized by these organisms when available. The respiratory quotient varies from 1.56–2.2. Anaerobic metabolism of flukes with ligatured oral openings is identical with intact organisms. This indicates that neither the absorption of glucose from outside medium, nor the excretion of the metabolic products are carried out through the gut of the organism.