Biochemical characterization of a GH19 chitinase from Streptomyces alfalfae and its applications in crystalline chitin conversion and biocontrol

Novel Bi-Modular GH19 Chitinase with Broad pH Stability from a Fibrolytic Intestinal Symbiont of Eisenia fetida, Cellulosimicrobium funkei HY-13

“…It should also be noted that sequence identities between the ChtBD3 domain of ChiJ and that of S. griseus HUT6037 GH19 chitinase (BAA23739) [ 25 ] and C. shinanonensis SAY3 T GH19 chitinase (BAK53965) [ 27 ] were assessed to be 53.6% and 53.5%, respectively. In ChiJ, the two putative catalytic residues (Glu174 acting as the proton donor and Glu183 acting as the nucleophile/base) and four conserved substrate-binding site residues (His173, Asn221, Asn284, and Arg300) were predicted in the active site of the enzyme, as exist in other GH19 functional homologs [ 27 , 28 , 29 ].…”

“…When determined by SDS-PAGE ( Figure 3 ), the relative molecular mass of purified (His) 6 -tagged rChiJ was estimated to be approximately 30.0 kDa, which was consistent with its deduced molecular mass (30,955 Da). The molecular size of rChiJ was relatively similar to that of S. griseus HUT6037 GH19 chitinase (28.5 kDa) [ 25 ], Streptomyces alfalfae ACCC 40021 GH19 chitinase (29.0 kDa) [ 29 ], Streptomyces cyaneus SP-27 GH19 chitinase (29.0 kDa) [ 32 ], and Streptomyces sampsonii XY2-7 GH19 chitinase (30.0 kDa) [ 33 ], as listed in Table 1 . However, bi-modular rChiJ was assessed to have a much smaller molecular mass than other characterized functional homologs such as Aeromonas sp.…”

“…The optimum pH (5.5) of rChiJ was very similar to that (5.6) of C. shinanonensis SAY3 T GH19 chitinase, which exhibited the highest degradation activity for colloidal chitin at 50 °C [ 27 ]. However, unlike rChiJ, some bacterial GH19 chitinases listed in Table 1 have been reported to be most active toward colloidal chitin at neutral or alkaline pH values [ 28 , 29 , 32 , 35 ]. In addition, the optimum temperature (55 °C) of rChiJ was significantly comparable to that of Aeromonas sp.…”

“…No. 10S-24 GH19 chitinase [ 34 ], Streptomyces griseus MG3 GH19 chitinase [ 36 ], S. alfalfae ACCC 40021 GH19 chitinase [ 29 ], Nosema bombycis (Nb) GH19 chitinase [ 35 ], and P. tunicata GH19 chitinase [ 28 ] that most efficiently decomposed colloidal chitin at temperatures below 45 °C. However, similar to rChiJ, S. griseus HUT6037 GH19 chitinase [ 25 ] and S. sampsonii XY2-7 GH19 chitinase [ 33 ] were shown to maximally degrade the substrate at 55 °C.…”

The Biocontrol and Plant Growth-Promoting Properties of Streptomyces alfalfae XN-04 Revealed by Functional and Genomic Analysis

“…Since chitin is the most abundant component of the fungal cell wall, chitinases have been widely demonstrated to be important inhibitors of fungal growth ( Taechowisan et al, 2003 ). A recent study showed that the GH19 chitinase cloned from S. alfalfae ACCC40021 exhibited great capability for inhibiting the growth of phytopathogenic fungi ( Lv et al, 2021 ). In the present study, XN-04 exhibited the ability to degrade chitin on agar plates, which was also confirmed by the identification of the genes related to chitin degradation in its genome.…”