The importance of strong inocula in fungal cultures

Abstract

Inoculum quality as starters of industrial fermentations, as well as propagules (conidia) from entomopathogenic fungi, is an important parameter that could define the success of either fermentation or biocontrol agents. Strong quality inocula have the potential to overcome some disadvantages from industrial scale bioprocesses, compared to chemical processes, which in some cases are shared with biocontrol agents compared to chemical pesticides. Features of strong inocula include the ability to accumulate compatible solutes to withstand harsh conditions such as high temperature, and also high catalase activity to deal with reactive oxygen species generated by respiration. Some of these biochemical features are determined by the age of the inoculum, which in addition to the standardization of inoculum size, reduce the variability inherent to microbial processes, and also increase product yields. In some cases, the inoculum barriers from a single strain may be overcome by the co-culture of different microorganisms. Finally, novelty methodologies are discussed to obtain strong inocula by culturing fungi and yeast under sublethal stress conditions that induce cross-protection to resist other kind of stresses.