Summary
Many antibiotics and other high-value compounds are produced industrially by growing filamentous Streptomyces bacteria in liquid culture, but in submerged fermentation these microbes tend to clump into dense pellets that limit productivity. Immobilising the cells on a porous support can prevent this clumping and boost biosynthesis. Here the authors electrospin poly(lactic acid) (PLA) into nanofibrous membranes and treat their surface with oxygen plasma. The plasma step adds polar carboxyl and hydroxyl groups that make the normally hydrophobic PLA far more wettable, while leaving the nanofibre morphology intact — as confirmed by contact-angle and X-ray photoelectron measurements. Used as a growth support for Streptomyces coelicolor in submerged culture, the plasma-treated PLA membranes raised the yield of the antibiotic actinorhodin roughly ten-fold compared with free-cell cultivation.