Efficient itaconic acid production from glycerol with Ustilago vetiveriae TZ1

Abstract

BackgroundThe family of Ustilaginaceae is known for their capability to naturally produce industrially valuable chemicals from different carbon sources. Recently, several Ustilaginaceae were reported to produce organic acids from glycerol, which is the main side stream in biodiesel production.ResultsIn this study, we present Ustilago vetiveriae as new production organism for itaconate synthesis from glycerol. In a screening of 126 Ustilaginaceae, this organism reached one of the highest titers for itaconate combined with a high-glycerol uptake rate. By adaptive laboratory evolution, the production characteristics of this strain could be improved. Further medium optimization with the best single colony, U. vetiveriae TZ1, in 24-deep well plates resulted in a maximal itaconate titer of 34.7 ± 2.5 g L−1 produced at a rate of 0.09 ± 0.01 g L−1 h−1 from 196 g L−1 glycerol. Simultaneously, this strain produced 46.2 ± 1.4 g L−1 malate at a rate of 0.12 ± 0.00 g L−1 h−1. Due to product inhibition, the itaconate titer in NaOH-titrated bioreactor cultivations was lower (24 g L−1). Notably, an acidic pH value of 5.5 resulted in decreased itaconate production, however, completely abolishing malate production. Overexpression of ria1 or mtt1, encoding a transcriptional regulator and mitochondrial transporter, respectively, from the itaconate cluster of U. maydis resulted in a 2.0-fold (ria1) and 1.5-fold (mtt1) higher itaconate titer in comparison to the wild-type strain, simultaneously reducing malate production by 75 and 41%, respectively.ConclusionsThe observed production properties of U. vetiveriae TZ1 make this strain a promising candidate for microbial itaconate production. The outcome of the overexpression experiments, which resulted in reduced malate production in favor of an increased itaconate titer, clearly strengthens its potential for industrial itaconate production from glycerol as major side stream of biodiesel production.

Mitochondrial carriers of Ustilago maydis and Aspergillus terreus involved in itaconate production: same physiological role but different biochemical features

“…So far, it was assumed that Um_Mtt1 catalyzes the export of mitochondrial cis‐aconitate, probably in exchange with cytosolic malate. However, this assumption is only supported by indirect physiological evidence, such as the secretion of malate in an mtt1 deletion strain of U. vetiveriae .…”

“…So far, it was assumed that Um_Mtt1 catalyzes the export of mitochondrial cis-aconitate, probably in exchange with cytosolic malate. However, this assumption is only supported by indirect physiological evidence, such as the secretion of malate in an mtt1 deletion strain of U. vetiveriae [29]. In order to experimentally verify this hypothesis, we carried out transport assays on the purified bacterially recombinant protein reconstituted into liposomes.…”

Ustilago Rabenhorstiana—An Alternative Natural Itaconic Acid Producer

“…All in all, detailed examinations are available for itaconic acid production of U. maydis, but also other wildtype strains of the family Ustilaginaceae could offer advantages of less sensibility or a yeast-like morphology for using second-generation feedstocks. This family is well-known for organic acid production [16,18,28,29], but the level of knowledge about alternative itaconic acid producer, like U. cynodontis or U. rabenhorstiana, are low.This study considers the cultivation of Ustilago rabenhorstiana for itaconic acid production and its potential as alternative natural producer. Although the used strain is known as natural itaconic acid producer [18,30], the microorganism was not examined in literature more precisely.…”

“…Although the used strain is known as natural itaconic acid producer [18,30], the microorganism was not examined in literature more precisely. Only the growth of the organism with glycerol as substrate was described, whereby non-formation of organic acids was detected [28]. Concerning itaconic acid production based on renewable resources, usability of different sugar monomers and robustness towards influence of sugar degradation products were examined in this study.…”

“…All in all, detailed examinations are available for itaconic acid production of U. maydis, but also other wildtype strains of the family Ustilaginaceae could offer advantages of less sensibility or a yeast-like morphology for using second-generation feedstocks. This family is well-known for organic acid production [16,18,28,29], but the level of knowledge about alternative itaconic acid producer, like U. cynodontis or U. rabenhorstiana, are low.…”