Controlling the simultaneous production of laccase and lignin peroxidase from Streptomyces cinnamomensis by medium formulation

The activities of laccase and LiP from S. cinnamomensis cultured with the optimal medium formulations were improved to be five to eight folders of their initial activities, and the measured laccase:LiP activity ratios reached 0.1, 0.4 and 1.7 when cultured on medium with formulations designed to produce laccase:LiP complexes with theoretical laccase:LiP activity ratios of 0.05 to 0.1, 0.5 to 1 and 1.1 to 2.Both the laccase and LiP activities and also the activity ratio of laccase to LiP could be controlled by the medium formulation as designed. Using a crude laccase-LiP complex with a specially designed laccase:LiP activity ratio has the potential to improve the degradation of various plant lignins composed of diverse monolignols with different abundance levels.Lignocellulose degradation is the central process for carbon recycling in land ecosystems [1]. As the key step in lignocellulose decay, lignin degradation, removal or modification is the rate-limiting step of carbon recycling [1,2], and also the central issue for industrial utilization of plant biomass (for example, biofuel production from abundant and renewable lignocellulosic material) [3,4]. Compared with the lignocellulosic biomass degradation by fungi, in vitro treatment of such biomass by lignin-degrading enzymes has a number of advantages, such as shorter incubation period without bacterial growth, reduced possibility of infection during large-scale microbe culture, lack of inhibitory effect of toxic byproducts (such as furfural) on bacterial or fungal mycelial growth, and improved reaction efficiency of bacterial enzymes at higher temperatures [1,5]. However, lack of commercially available, robust, and inexpensive enzymes is a major barrier for the widespread application of ligninolytic enzymes in various industrial sectors [5,6]. To avoid the high costs associated with enzyme purification procedures, one of the most promising ways to promote lignin biodegradation is to use crude enzymes [5-8].Lignin