Changes in the Functionality of Plasma Membrane of Rhizopus stolonifer by Addition of Chitosan

Abstract

The effect of chitosan (2 mg ⁄ ml) on the functionality of the plasma membrane of the Rhizopus stolonifer was studied. This study focuses on the changes in the integrity of the plasma membrane, external minimum medium pH, membrane potential, potassium efflux and determination of membrane phospholipids and proteins and of the H + -ATPase enzymatic kinetic activity. The results demonstrated that the membrane integrity diminishes gradually during 6 h of incubation, that there was no change in the external minimum medium pH and that the spores treated with chitosan showed the lowest membrane potential compared with the control. The results also revealed an increase of five times of potassium efflux by the addition of chitosan. There were no significant observed differences in the content of total phospholipids in both treatments. However, protein content was reduced approximately 40% and total H + -ATPase activity decreased 52% in the presence of chitosan. Chitosan treatments diminished the kinetic parameters (Vmax and Km) of the H + -ATPase activity. The damage to the plasma membrane of R. stolonifer by the presence of chitosan alters the H + -ATPase, affecting the physiological and metabolic functions of this phytopathogen fungus.

Response of Ustilago maydis against the Stress Caused by Three Polycationic Chitin Derivatives

“…As reported before, chitosan promotes has a complete inhibitory effect on Ustilago maydis as a consequence of the interaction between specific sites in the plasma membrane and protonated free amino groups, constituting the main change of the polymer [ 15 ]. The modifications in cell permeability explain the depletion of the membrane potential and are consistent with observations in Rhizopus stolonifer at a chitosan concentration of 2000 µg·mL −1 [ 15 , 30 ]. However, in a non-susceptible model, such as Candida albicans , the effect of chitosan on the plasma membrane is completely the opposite: Peña et al [ 31 ] described hyperpolarization of the cell membrane of C. albicans due to an alignment of internal charges with a subsequent increase in potential membrane when the yeast was in the presence of low chitosan concentrations [ 31 ].…”

Influence of chitosan and its derivatives on cell development and physiology of Ustilago maydis

“…After that a basal potassium flow was determined, and variable concentrations of each antifungal compound (2-100 g/mL) were added as indicated in the figure legends. The experiments were carried out at 30 • C in a 10-mL chamber with continuous magnetic stirring [17].…”

“…All other chemicals and solvents used were of analytical grade. A stock solution of chitosan (10 mg/mL) was prepared with 1 g of chitosan dissolved in 100 mL of 1% acetic acid and stirred for 24 h. The pH was adjusted to 5.6, and this solution was sterilized by autoclaving [17]. To prepare stock solutions of oligochitosan and glycol chitosan (40 mg/mL), 8 g of each was dissolved in 200 mL of distilled water and stirred for 2 h. pH of both solutions was adjusted to 7.0, and they were sterilized by filtration through 0.45-m membranes [9].…”

Quitosano y mucílago de Opuntia ficus-indica (nopal) como base de una película polimérica comestible para la protección de tomates contra Rhizopus stolonifer

“…We propose a global mechanism that includes electrostatic interactions with the plasma membrane (the most accepted model) and a series of stress conditioning elements (such as the formation of reactive oxygen species) and a complex metabolic imbalance (Olicón-Hernández et al, 2015;Olicón-Hernández, Uribe-Álvarez et al, 2017). With respect to the effect of chitosan on R. stolonifer, it was observed that the polymer modified the germination of spores, affected fungal morphology, increased glucose consumption, inhibited H + -ATPase activity in the plasma membrane and caused a high potassium efflux (Dos Santos et al, 2012;García-Rincón et al, 2010;Guerra-Sánchez, Vega-Pérez, Velázquez-del Valle & Hernández-Lauzardo, 2009;Hernández-Lauzardo et al, 2008;Hernández-Lauzardo et al, 2011). An increase in the shelf-life of different fruits using edible CS-OM films has been observed in recent years, which is in agreement with the results of the present study (Ávila-Sosa et al, 2012;Treviño-Garza et al, 2017).…”