β‐poly(l‐malic acid) production by fed‐batch culture of Aureobasidium pullulans ipe‐1 with mixed sugars

Abstract

Research Article β-poly(L-malic acid) production by fed-batch culture of Aureobasidium pullulans ipe-1 with mixed sugars β-poly(l-malic acid) (PMLA) is a biopolyester, which has attracted growing attention due to its potential applications in medicine and other industries. In this study, the biosynthetic pathway of PMLA and the fermentation strategies with mixed sugars were both investigated to enhance PMLA production by Aureobasidium pullulans ipe-1. Metabolic intermediates and inhibitors were used to study the biosynthetic pathway of PMLA. It showed that exogenous addition of l-malic acid, succinic acid, TFA, and avidin had negligible effect on PMLA production, while pyruvic acid and biotin were the inhibitors, indicating that PMLA biosynthesis was probably related to phosphoenolpyruvate via oxaloacetate catalyzed by phosphoenolpyruvate carboxylase. Sucrose was suitable for achieving the highest PMLA concentration, while fructose generated a higher yield of PMLA (PMLA produced per biomass). Furthermore, the fed-batch culture using fed solution with different sugar mixture for PMLA production was implemented. During the fed-batch culture with mixed solution, fructose could increase PMLA production. Compared with the batch culture, the feeding with mixed sugar (sucrose and glucose) increased PMLA concentration by 23.9%, up to 63.2 g/L, and the final volume of the broth was increased by 25%. These results provide a good reference for process development and optimization of PMLA production.

One step separation of Aureobasidium pullulans from β‐poly(L‐malic acid) fermentation broth by membranes technology

“…To measure the amount of total malic acid (including PMLA and free malic acid), 1 mL of supernatant was incubated with 1 mL of 2 mol L −1 H 2 SO 4 for 12 h at 90°C. After neutralization of the solution, L‐malic acid concentration was measured by a HPLC apparatus (Shimadzu LC20AT) as described in Cao et al , except for equipping with an Aminex HP‐X87H lon Exclusion column and H 2 SO 4 as moving phase. The process was performed at a temperature of 40°C, a flow rate of 0.6 mL min −1 , an absorbance wavelength of 210 nm and with 5 mmol L −1 H 2 SO 4 as moving phase.…”

“…The culture broth (8 mL) was centrifuged at 10 000 × g for 8 min and the resulting supernatants was used for the measurement of PMLA and glucose. For the measurement of biomass content, the cells were washed three times with 8 mL of distilled water, then dried to constant weight at 90 ∘ C. To measure the amount of total malic acid (including PMLA and free malic acid), 1 mL of supernatant was incubated with 1 mL of 2 mol L −1 H 2 SO 4 for 12 h at 90 ∘ C. After neutralization of the solution, L-malic acid concentration was measured by a HPLC apparatus (Shimadzu LC20AT) as described in Cao et al, 10…”

Effects of Corn Steep Liquor on ß-poly(L-malic Acid) Production in Aureobasidium Melanogenum

“…Moreover, the researcher speculated that the metabolic pathway of PMLA may vary in different strains. The research found that PMLA production is considerably associated with the glyoxylate pathway in Physarum polycephalum with the addition of intermediates and inhibitors (Lee et al 1999 ) , and it can also be catalyzed by nonbiotin-dependent carboxylation, which is related to the rTCA pathway in A. pullulan (Cao et al 2014). Due to the varied biosynthesis pathways for PMLA production, it is challenging to construct the genetically engineered strains.…”

Evaluation of surfactant effect on β-poly(L-malic acid) production by Aureobasidium pullulans

“…PMLA has outstanding features as biocompatibility, biodegradability, water solubility, absorbability, nonimmunogenicity and easy chemical modification [1]. Therefore, PMLA and its derivatives may have great potential for applications in the drug delivery field and the production of advanced biomaterials [1,3,4].…”

“…To meet the increasing demand for PMLA, it has become necessary to improve the efficiency of PMLA production. Numerous approaches have been developed to improve PMLA production, including screening for high-yield mutant strains, investigating improvements to fermentation modes and strategies, optimisation of carbon sources, adding exogenous substances and control of agitation speed [3,7,8]. In our study, we have focussed on developing methods to weaken the resistance of cells to the movement of substances into/out of them and to enhance PMLA production.…”