Screening of spontaneous mutants of Streptomyces SP. CAAT 7-52 aiming a high albocycline production

Abstract

Actinobacteria have attracted the attention of researchers in the most diverse fields of research. In particular, in the agricultural area, these bacteria stand out due to their potential as biological control agents and as producers of compounds with fungicidal and herbicidal properties. In fact, more than 65% of all compounds of microbial origin come from the phylum Actinobacteria. However, the rate of discovery of new chemical molecules has been declining and some compounds of interest are produced in small quantities, making it difficult to analyze chemistry further. Since 2002 when the first genome of an actinobacterium was published, there has been a growing use of genomic tools in an attempt to increase the rate of discovery of new bioactive compounds. In practice, these studies have revealed that some secondary metabolites, encoded in genomes, remain to be discovered, probably because these genes are not transcribed under conditions of conventional fermentations in the laboratory, and therefore these genes were determinated as "silenced genes". As an alternative, several strategies have been applied for the activation of silenced microbial pathways or overproduction of target compounds, such as modifications of the culture medium, heterologous and homologous expression, co-culture and ribosomal engineering. Among them, ribosomal engineering seems to be more viable due to the simplicity of the method and the fact that it does not require the global knowledge of the bacterial genome. In this sense, the objective of this project is to apply the ribosomal engineering strategy to activate or induce the expression of genes that may be involved in the synthesis of antibiotics. For this purpose, a candidate strain to one new species, Streptomyces sp. CAAT 7-52, which presents a discrete albocycline production that is effective to control several phytopathogenic fungi, will be used as a model to obtain mutant strains that are superproducers of antibiotics.