Insights into the mechanism of mycelium transformation of Streptomyces toxytricini into pellet

Abstract

Formation of the mycelial pellet in submerged culti v ation of Streptomycetes is unwanted in industrial fermentation processes as it imposes mass transfer limitations, changes in the rheology of a medium, and affects the production of secondary metabolites. Though detailed information is not av aila b le a bout the factors inv olv ed in r e gulating m ycelial morphology, it is studied that culture conditions and the genetic information of strain play a crucial r ole. Mor eov er, the pr oteomic study has r ev ealed the inv olv ement of low molecular w eight proteins suc h as; DivIVA, F ilP, P arA, Sc y, and SsgA proteins in apical growth and br anc hing of hyphae , whic h results in the esta b lishment of the m ycelial netw ork. The present study proposes the mechanism of pellet formation of Str eptom yces toxytricini (NRRL B-5426) with the help of microscopic and proteomic analysis. The microscopic analysis revealed that growing hyphae contain a bud- like structure behind the apical tip, which follows a certain organized path of growth and br anc hing, whic h was further converted into the pellet when shake flask to the shake flask inoculation was performed. Proteomic analysis revealed the production of low molecular weight proteins ranging between 20 and 95 kDa, which ar e inv olv ed in apical growth and hyphae br anc hing and can possib l y participate in the regulation of pellet morphology.