Bioprocessing strategies for cost-effective large-scale production of bacterial laccase from Lysinibacillus macroides LSO using bio-waste

Abstract

Investment in green chemistry to convert agro-industrial residues into value-added products could be economically feasible. The present study proved the utility of sugarcane bagasse as an inexpensive and easily available raw material for large-scale production of extracellular laccase from a newfound bacterial strain Lysinibacillus macroides LSO isolated from Alexandria paper and pulp industry effluents. To maximize the efficiency of laccases, a sequential optimization strategy focused on computational experimental designs accompanied by a bench-scale bioreactor batch cultivation strategy was adopted. Among the twelve variables analysed, sugarcane bagasse, NH4Cl, CuSO4·5H2O, and MnSO4·H2O were chosen based on their high positive significant impact on laccase productivity via the 2-level Plackett–Burman design (PBD). Rotatable Central Composite Design (RCCD) was exploited to create a polynomial quadratic model correlating the relationship between the four variables and the productivity of laccase. The highest extracellular laccase productivity and specific growth rate (µ) were achieved at the early period of the incubation time through cultivation Lysinibacillus macroides LSO in a 10-L stirred tank bioreactor under batch operation conditions. Laccase yield 7653.2 U L−1 min−1 and µ = 0.024 h−1, respectively, were obtained after 28 h that increased more than 70.861-, 4.181-, and 1.934-fold compared to basal media, PBD, and RCCD, respectively. Utilization of bio-waste for scaling up the production of extracellular bacterial laccase from Lysinibacillus macroides strain LSO via bioreactor scale