Microbial production of organic acids by endophytic fungi

- Endophytic fungi are potential source for organic acids production.
- A. awamori strain was cultivated under SSF with wheat bran and sugarcane bagasse.
- Organic acids were produced using agro-industrial wastes as renewable feedstock.
- Endophytic fungi could be used to obtain building-block chemicals in biorefineries.

The microbial production of organic acids has been considered as a promising strategy to obtain building-block chemicals from renewable feedstocks such as lignocellulosic agro-industrial wastes. This approach is in accordance with the biorefinery concept where the production of biofuels is integrated to higher-value platform chemicals. However, finding a suitable microbial source and the optimum cultivation conditions remains a challenge for the implementation of such process. Endophytic microorganisms have been explored as a source of novel biochemical compounds for biotechnological applications, but the production of organic acids by endophytic fungi remains to be investigated. Here, the potential of using endophytic fungi for organic acids production has been evaluated by carrying out a screening of 35 fungal strains isolated from the leaves and branches of trees inhabiting two mangroves in the state of Sao Paulo, Brazil. The cultivation of a selected Aspergillus awamori 09 (4) strain under solid-state fermentation (SSF) using a mix of wheat bran and sugarcane bagasse (1:3) resulted in 135.5 mg/g of organic acids, which represents around 7-fold increase when compared to the use of sugarcane bagasse alone. These results indicate the potential of mangrove-associated endophytic fungi for organic acid production under SSF using agro-industrial wastes as feedstock, being compatible with the current bioeconomy demands.