Poly(β-L-malic acid) production by diverse phylogenetic clades of Aureobasidium pullulans

Abstract

Poly(β-L-malic acid) (PMA) is a natural biopolyester that has pharmaceutical applications and other potential uses. In this study, we examined PMA production by 56 strains of the fungus Aureobasidium pullulans representing genetically diverse phylogenetic clades. Thirty-six strains were isolated from various locations in Iceland and Thailand. All strains from Iceland belonged to a newly recognized clade 13, while strains from Thailand were distributed among 8 other clades, including a novel clade 14. Thirty of these isolates, along with 26 previously described strains, were examined for PMA production in medium containing 5% glucose. Most strains produced at least 4 g PMA/L, and several strains in clades 9, 11, and 13 made 9-11 g PMA/L. Strains also produced both pullulan and heavy oil, but PMA isolated by differential precipitation in ethanol exhibited up to 72% purity with no more than 12% contamination by pullulan. The molecular weight of PMA from A. pullulans ranged from 5.1 to 7.9 kDa. Results indicate that certain genetic groups of A. pullulans are promising for the production of PMA.

An aubasidan-like β-glucan produced by Aureobasidium pullulans in Thailand

“…Most of these strains produced pullulan with only a few exceptions, such as the strains NRRL 58539 and NRRL 58543. However, the structure of EPS produced from the NRRL 58539 and NRRL 58543 strains have not been characterized in previous reports 5,7 . This study is the first report of aubasidan-like β-glucan-producing strains of A. pullulans isolated in Thailand.…”

“…Previous multilocus DNA sequence analyses suggested that both strains were not A. pullulans var. pullulans because they grouped in a different clade 5,7 . However, representative strains of the three varieties of A. pullulans, (var.…”

“…(NRRL 58539 and NRRL 58543) were separately isolated from different areas in Thailand. Multilocus DNA sequence analysis suggested that these two strains were probably not A. pullulans since they were grouped together in a separate clade from the other A. pullulans strains 5,7 . In this study, the nutrient assimilation profile and the preferred nitrogen source for EPS production of these Aureobasidium strains were investigated.…”

Intensification of β-poly(l-malic acid) production by Aureobasidium pullulans ipe-1 in the late exponential growth phase

“…PMLA can be produced by either chemical synthesis [10] or microbial fermentation [17]; the latter approach has been extensively investigated. Leathers et al [17] did signiWcant work on PMLA production by strains of Aureobasidium pullulans representing genetically diverse phylogenetic clades, some of which included strains produced relatively high levels of PMLA.…”

Aureobasidium thailandense sp. nov. isolated from leaves and wooden surfaces

“…Some isolates of A. pullulans produce semiochemicals (Davis et al, 2012) that influence wasp behaviour in nature and that may be involved in dispersal of members of the genus Aureobasidium, while other isolates produce large amounts of the extracellular polysaccharide (EPS) pullulan (Manitchotpisit et al, 2009), a polysaccharide with many valuable industrial and medical uses (Leathers, 2002;Cheng et al, 2011). Still other isolates biosynthesize products that have commercial value such as laccase (Rich et al, 2011), xylanase (Manitchotpisit et al, 2009) or poly b-L-malic acid (Manitchotpisit et al, 2012).…”