Glucosidase Activity in Acanthamoeba (Mayorella) palestinensis. The Effect of Glucose and Natural Glucosides on α‐ and β‐Glucosidases

Abstract

SYNOPSIS. Acanthamoeba (Mayorella) palestinensis produces high basal levels of α‐ and β‐glucosidases, the latter being much more active than the former. Glucose, an essential growth substance, has a dual effect on the glucosidase activity. Growth concentrations (1%) of glucose inhibit, while low levels elevate the activity of both enzymes. Natural α‐glucosides support growth in the same manner as glucose and raise the activity of both enzymes to the same extent. β‐glucosides, on the other hand, are weak growth substrates, but stronger inducers, especially for β‐glucosidase activity. The role of the glucosidases in the over‐all metabolism of the ameba is discussed.

Stimulation of Acanthamoeba castellanii excystment by enzyme treatment and consequences on trophozoite growth

“…Moreover, as empty cyst walls are no longer visible in culture following A. castellanii excystment in the absence of cellulase, it is conceivable that trophozoites would secrete their own cellulase during this cellular process allowing cyst wall degradation and amoebae proliferation, but with a much lower efficiency than in the presence of an additional cellulase. These data are in agreement with the studies previously describing the release of cellulase as well as proteases during Acanthamoeba culbertsoni excystment ( Lasman 1975 ; Kaushal and Shukla, 1978a ; Kaushal and Shukla, 1978b ; Krishna-Murti and Shukla, 1984 ; Kaushal and Shukla, 1976 ). Moreover, as the monosaccharide composition of Acanthamoeba cyst wall is mainly constituted of glucose and galactose ( Anwar et al, 2019 ), these carbohydrates could be released after cyst wall digestion during excystment and further used as an energy source or to synthesize glycoconjugates within the trophozoite.…”

“…As a cysticidal effect was previously observed with cellulase at concentrations of 500 U/mL and 1500 U/mL on Acanthamoeba sp. (Ortilles et al, 2017;Lazuana et al, 2019), we treated A. castellanii cysts with a range of lower concentrations, from 5 U/mL to 50 U/mL, in order to avoid cyst death. Different conditions of temperatures, from 27 to 37 °C, and incubation times, from 24 to 72 h, were also evaluated in order to determine optimal conditions of treatment (Figure 1).…”

“…In order to avoid any toxic effect of enzyme treatment, cellulase was used with a range from 5 U/mL to 50 U/mL, much lower than the concentrations of 250 U/mL and 1500 U/mL previously described to cause less than 20% and less than 50% of cyst death, respectively (Lazuana et al, 2019), and proteases were used with a similar range, from 5 U/mL to 100 U/mL. As a result, in comparison to untreated A. castellanii cysts which need 11 days to completely excyst at 27 °C, only 48 h were sufficient to give more than 96% of excystment at the same temperature in the presence of 50 U/mL of collagenase, 100 U/ mL pepsin or 25 U/mL cellulase.…”

“…Some studies have reported a cysticidal effect of cellulase and a subtilisin-like serine protease treatment on Acanthamoeba sp. and Vermamoeba vermiformis, respectively (Fouque et al, 2015a;Ortilles et al, 2017;Lazuana et al, 2019). Moreover, in several Acanthamoeba species, treatments by cellulase and pancreatic protease can hydrolyze more than half of cyst wall carbohydrates and proteins, respectively (Barrett and Alexander, 1977).…”

Exocellular Carbohydrase Formation by Rumen Holotrich Ciliates

“…Besides invertase, several other glycosidases and p-nitrophenyl acid hydrolases were detected extracellularly. Such enzymes are widely distributed among microorganisms and, like Tetrahymena pyriformis (7) and Acantharnoeba palestinensis (20), may occur extracellularly. The activity of many of the exocellular enzymes was low, although the exocellular activity represented -2-3% of the total activity of that enzyme in the microorganisms.…”