Actinobacteria hydrolase producer in solid-state fermentation using licuri

Abstract

In recent times, green technologies have gained space and interest in many industrial sectors. Examples of this are enzymes, which can be obtained by solid-state fermentation using microorganisms and agro-industrial residues as substrates. In this context, this study aimed to verify the production of hydrolases leading to Arthrobacter polychromogenes and Streptomyces violaceoruber strains as producers and the influence of moisture and residues of licuri [Syagrus coronata (Martius) Beccari] and wheat as substrates. The solid-state fermentation was performed at 28 °C/12 days, with different ratios of wheat bran/degreased almond licuri cake: 0/70%, 10/60%, 35/35%, 60/10% and 70/0%; and licuri peel, set at 30%. The medium moisture ranged from 29 to 67%. Licuri peel was added to facilitate aeration of the medium; wheat bran is commonly used to produce lipases and pectinases; and degreased almond licuri cake is the substrate of interest in this work, since it was inspired by the extractive production of licuri in the semiarid region of Brazil. The wheat bran/degreased almond licuri cake ratio did not affect enzyme production by A. polychromogenes; however, with S. violaceoruber, the ratio value was significant for lipase production but not for pectinases. The medium prepared with 67% moisture and equal ratios of wheat bran and degreased almond licuri cake (35/35%) presented the highest enzymatic activities for both enzymes, 840.46 U/gds for lipases and 15.53 U/gds for pectinases, during Composite Central Design assays. With validation experiments, it was verified that licuri residues can be used as substrates for the production of hydrolases by solid-state fermentation and that actinobacteria evaluated are suitable microorganisms.