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Abstract: In the present study, the influence of volumetric airflow rate and rice husk as a bulking agent were evaluated in packed bed bioreactors to the production of lipopeptide iturin A. The iturin A is a powerful antifungal composed by seven α-amino acid rings linked to a β-amino fatty acid chain with an alkyl chain that can be linear or branched. The solid state fermentations (SSF) were carried out using a new strain Bacillus iso 1 as ferment and wheat bran and soybean meal as substrates at 30°C for 96h. It was found that the concentration of rice husk and volumetric airflow rate in the range of 20–40% (w/w) and 0.4–0.8L/min are important operational parameters for the production of iturin A in packed bed bioreactors. The highest iturin A production (6.88g/kg of dry substrate) was achieved when SSF was carried out with a 22.9% (w/w) of rice husk and a volumetric airflow rate of 0.46L/min. These promising results show the potential of the new strain Bacillus iso 1 to produce high concentrations of lipopeptide iturin A using cheap agro-industrial substrates in packed bed bioreactors with forced aeration, in order to develop an industrial production processes. [Copyright &y& Elsevier]

Succinic acid is a four-carbon dicarboxylic acid used as a building-block in the synthesis of valuable commodities and specialty chemicals. Succinic acid is produced petrochemically by hydrogenation of maleic anhydride and a "greener" alternative route is microbial fermentation. In this study, a 25−1 fractional factorial design (FFD) and a subsequent central composite rotatable design (CCRD) were used to investigate the influence of process parameters on succinic acid and biomass concentration during fermentation by Actinobacillus succinogenes. The independent factors were glucose concentration (19.29–42.45 g/L), yeast extract concentration (5–11 g/L), temperature (33–41 °C), pH (6–8), and agitation speed (100–300 rpm). Results showed that the main factors that influenced the succinic acid production were pH, yeast extract concentration and temperature. According to the CCRD results, the optimum conditions for succinic acid production were 37–41 °C, 13 g/L yeast extract concentration and pH 7. The maximum succinic acid concentration obtained was 17.5 g/L. • Microbial fermentation is a cleaner alternative to produce succinic acid. • Process parameters were optimized to enhance succinic acid and biomass content. • Succinic acid productivity was increased 1.5 times through optimization. [ABSTRACT FROM AUTHOR]