**1. Introduction**

Chitin, which can be easily isolated from crab and shrimp shell waste, is the second most abundant biopolymer on earth. At least 10 gigatons (1 × 1013 kg) of chitin are synthesized and degraded each year in the biosphere. *N*-Acetylchitooligosaccharides (GlcNAc) and chitooligosaccharides (GlcN), which are hydrolyzed products of chitin and chitosan, have various biological roles and many possible future applications [1–3]. GlcNAc and glucosamine are ordinarily utilized for symptom relief in osteoarthritis patients [4]. Hyaluronic acid as heterogeneous polysaccharides contained GlcNAc, and addition of GlcNAc to cultured keratinocytes facilitates the production of hyaluronic acid in a dose-dependent manner [5].

Biotechnological tools for generating enzymes are required for environmentally sustainable production of chitin oligosaccharide, GlcNAc, or both. Multiple chitinases have been characterized and are categorized into four enzyme families, namely, families 18, 19, 23, and 48 [6, 7]. The glycoside hydrolase (GH) families 18 and 19 chitinases have almost no amino acid sequence similarities and have entirely different three-dimensional structures. Ra-ChiC from *Ralstonia* sp. A-471 was the first chitinase of the GH family 23 [7] and has been categorized to goose-type lysozyme. However, although Ra-ChiC shows chitinase activity, no activity toward peptidoglycan has been described [7]. β-GlcNAcase (exo-type enzyme) belongs to GH family 20. Chitin oligosaccharides such as *N*-acetylchitobiose and *N*-acetylchitotriose are good substrates for β-GlcNAcase [8]. Lytic polysaccharide monooxygenases (LPMOs, auxiliary activity [AA] family 10) are copper-dependent and cleave polysaccharide chains embedded in the crystalline regions of the substrate that are generally inaccessible to glycoside hydrolases [9]. Hemsworth et al. reported that fungi in particular makes considerable use of LPMOs in biomass degradation, producing more LPMO enzymes than cellulases [10]. Enzyme cocktails contained cellulases and LPMO enzymes can be utilized in the bio-refinery for lignocellulose deconstruction [10].

To understand the synergic activity of LPMO during the hydrolysis of crystalline chitin by chitinase A (GH family 18) and β-GlcNAcase from *Paenibacillus* sp., cloning and expression of chitinase A (Pb-ChiA), β-GlcNAcase (Pb-GlcNAcase), and LPMO (Pb-LPMO) genes from *Paenibacillus* sp. were carried out in this study.
