Optimization of laccase production and its application in delignification of biomass

Abstract

Purpose Current research focuses on the biological delignification of biomass by microbial laccase which is an environmentally friendly process. Methods Various statistical approaches were designed for optimization of laccase production like Plackett-Burman design as well as response surface methodology (RSM). A laccase mediator system was designed for the delignification of saw dust which was molecularly characterized by high-performance liquid chromatography (HPLC), Fourier transformation infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Results The present study reveals wheat bran is a potential substrate for the production of laccase (63 U/g and 9.6 mg/ g protein) under solid-state fermentation by Trichoderma harzianum strain HZN10. Statistical optimization by RSM using central composite design (CCD) revealed that wheat bran contributed maximally to the overall laccase production followed by yeast extract. Laccase production under optimized conditions yielded 510 U/g with 8.09-fold increase. HPLC peaks representing 4-hydroxy-3-methoxybenzoic (vanillic) acid and 4-hydroxy-3,5-dimethoxybenzoic (syringic) acid showed drastic reduction in laccasetreated saw dust sample indicating the elimination of toxic inhibitors, thereby signifying the detoxification of sample.The laccase-treated saw dust showed 1.6-fold increase in reducing sugars after enzymatic (cellulase) hydrolysis. The FTIR analysis revealed the structural alterations occurring during the delignification process. SEM of biologically treated saw dust revealed the morphological alterations during the delignification process targeting the fiber cell walls rich in lignin. Conclusion The delignification of saw dust was effective by laccase mediator system and was evidenced by HPLC, FTIR and SEM analysis. Hence, laccase can be a powerful tool in biomass to biofuel conversions.

Response surface methodology-based optimization of biosurfactant production from isolated Bacillus aryabhattai strain ZDY2

“…FTIR (PerkinElmer, FTIR1760) analysis was carried out to explore the presence of chemical functional groups in biosurfactant according to previous report (Bagewadi et al 2017). The extracted biosurfactant was freeze-dried by 3.0 (− 1) 0.7 (+ 1) 2.0 (− 1) 1.20 1.86 4 5.0 (+ 1) 0.7 (+ 1) 2.0 (− 1) 4.20 4.27 5…”

Cultivation of straw mushroom (Volvariella volvacea) on oil palm empty fruit bunch growth medium

“…Some methods, such as using supplemental micronutrients (Thiribhuvanamala et al2012), adequate fertilizers (Reyes 2000), mixed materials with low C-N ratios (Zakhary et al 1984), better aeration and drainage (Apetorgbor et al 2015), can be potentially used to improve EFB composting techniques. Usage of laccase-producing Trichoderma to breakdown lignin during the substrate fermentation as reported by Bagewadi and Mulla (2017) was also a potential option to apply.…”

Utilization of wheat straw for fungal phytase production

“…(Bhavsar et al 2011;Moreira et al 2014), Mucor racemosus (Bogar et al 2003b), and Sporotrichum thermophile (Singh andSatyanarayana 2006b, Maurya et al 2017), Thermomyces lanuginosus (Makolomakwa et al 2017), and Rhizopus oryzae (Arora et al 2017) have been reported to produce phytase. Several filamentous fungi and their enzyme products are used to break down the bond between the polysaccharides (cellulose and hemicellulose) and lignin in wheat straw to improve its digestibility through the process referred to as biological-pretreatment (Sindhu et al 2016, Choudhary et al 2016, Bagewadi et al 2017. Many previous studies have also reported the ability of filamentous fungi to produce various commercial enzymes from wheat straw (Table 1).…”