Development of a Cytosensor for the Detection of Fusarium Oxysporum - A Functional Approach Towards Bioanalytical Applications

Abstract

The development of bio-analytical methods for monitoring microorganisms have created opportunities for applications in biosensors, bioprocess monitoring, assessment of cell signalling, analysis of drug responses, among several others. The voltammetric sensing system employed for studying the electrode behavior of the fungus Fusarium oxysporum comprised working (gold) electrode (0.2 cm2 ) platinum as counter electrode (0.2 cm2 ) and a saturated calomel as the reference, where the electrochemical response corresponded to the growth phases (lag, log, stationary and decline) of the fungus. The electrochemical method based on voltammetric response matched well with the response obtained through conventional methodology, where the dry weight of the fungus is estimated against time. The peak potential is a function of scan rate, which is one of the characteristic features of a totally irreversible electrode process. It is important to mention here that this dependence is true regardless of reversibility for any diffusing redoxactive species. The proposed electrochemical method is less cumbersome and more accurate. Furthermore, the proposed electrochemical method captures the decline phase of fungal growth, which is generally difficult using the conventional method of assessment of the growth curve. Further experiments confirm that the anodic peaks were not due to the biomass or the fungal spores and only due to the extracellular metabolites. However, at this stage it is difficult to exactly determine the metabolite or the group of metabolites that are responsible for the anodic peak. In conclusion this cytosensor is capable of accurately and rapidly quantifying fungi with Fusarium oxysporum as a model organism.