ARS | Publication request: Poly(beta-L-malic acid) from agricultural substrates by Aureobasidium pullulans

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 30, 2012
Publication Date: August 30, 2012
Citation: Leathers, T.D., Manitchotpisit, P. 2012. Poly(beta-L-malic acid) from agricultural substrates by Aureobasidium pullulans [abstract]. International Congress on Yeasts. p. 326.

Technical Abstract: We report here for the first time the production of poly(beta-L-malic acid) (PMA) from agricultural substrates by the yeastlike fungus Aureobasidium pullulans. PMA is a natural biopolyester that has primarily been studied for biomedical uses as a drug carrier. However, PMA also has potential as a platform molecule for second-generation bioplastics. PMA derivatives have been used to make solid devices, compression molded pellets, films, and nanoparticles. PMA for pharmaceutical uses is conventionally produced from the myxomycete (slime mold) Physarum polycephalum. However, higher yields have been reported from A. pullulans. Even though A. pullulans is well-known as a source of biomass-degrading enzymes, previous studies have focused on PMA production from glucose or sucrose. For bulk biomaterials applications, it would be desirable to produce PMA from low-cost biomass substrates. We recently completed a multilocus molecular phylogeny of A. pullulans. Interestingly, certain phylogenetically defined clades produced high levels of specific bioproducts, including pullulan, xylanase, and heavy oil. We subsequently surveyed 56 strains representing all known clades for production of PMA from glucose. High levels of PMA production were found in several strains, including NRRL Y 2311-1, NRRL 50382, NRRL 50383, and NRRL 50384, representing clades 8, 11, and 13. In the current study, these strains are shown to produce PMA from alkaline hydrogen peroxide-pretreated corn fiber and wheat straw. The addition of CaCO3 and supplementary hydrolytic enzymes enhanced PMA production. The utilization of abundant, low-cost agricultural byproducts should reduce the cost of PMA production for industrial uses such as bioplastics. Results also indicate that PMA could represent a new bioproduct for biorefineries of the future, replacing petroleum-based plastic feedstocks.