Efficacy of chitosan synthesized from shrimp (Penaeus notialis) shell against Aspergillus flavus of groundnut and wheat

Abstract

Chitosan is a natural safe biopolymer that has received great attention in agriculture, food, biomedical, pharmaceutical and environmental industries because of their biocompatible, biodegradable and non-toxic. Chitosan used in this study was synthesized using shrimp shell through chemical processes viz. demineralization, deproteinization, decolourization and deacetylation. Antifungal activity of Chitosan Synthesized from Shrimp Shells (CSSS) was evaluated at different concentrations of 0.25mgml-1, 0.50 mgml-1, 0.75 mgml-1 and 1.0 mgml-1 against Aspergillus flavus. Shrimp shell synthesized chitosan gave off-white to light brownish semi-crystallized product. The protocol for the synthesis yield chitosan with 98.9% degree of deacetylation and Ultra Violet-visible spectra (UV-vis) at a wavelength of 232 nm. There were variations in mean mycelia growth of A. flavus at different concentrations of CSSS and incubation days. With increasing incubation days there was accompanying increase in mean mycelial growth of A. flavus. At day one mean mycelia growth were 0.75±.05, 1.40±.10, 1.55±.15 and 1.60±.10cm whilst at the fifth day of incubation, mycelia radial growth were 7.55±.55 3.10±2.4 , 6.45±.15 and 6.95±.95cm respectively at concentrations of 0.25, 0.50, 0.75 and 1.0 (mgml-1) of CSSS. Control had highest mycelia radial growth (8.05) as compared to the different concentrations of treated samples. Highest Percentage Inhibition of A. flavus (61.7%) by CSSS was recorded in 0.5mgml-1, however 6.80%, 20.4%, 14.2% inhibition were recorded in 0.25, 0.75 and 1.0mgml-1 concentrations respectively which were significantly different. It is evident from the study that shrimp shell synthesized chitosan are likely biocontrol agent capable of preventing A. flavus growth and toxin production.