Production of Antifungal Chitinase by Aspergillus niger LOCK 62 and Its Potential Role in the Biological Control

Abstract

Aspergillus niger LOCK 62 produces an antifungal chitinase. Different sources of chitin in the medium were used to test the production of the chitinase. Chitinase production was most effective when colloidal chitin and shrimp shell were used as substrates. The optimum incubation period for chitinase production by Aspergillus niger LOCK 62 was 6 days. The chitinase was purified from the culture medium by fractionation with ammonium sulfate and affinity chromatography. The molecular mass of the purified enzyme was 43 kDa. The highest activity was obtained at 40 °C for both crude and purified enzymes. The crude chitinase activity was stable during 180 min incubation at 40 °C, but purified chitinase lost about 25 % of its activity under these conditions. Optimal pH for chitinase activity was pH 6–6.5. The activity of crude and purified enzyme was stabilized by Mg2+ and Ca2+ ions, but inhibited by Hg2+ and Pb2+ ions. Chitinase isolated from Aspergillus niger LOCK 62 inhibited the growth of the fungal phytopathogens: Fusarium culmorum, Fusarium solani and Rhizoctonia solani. The growth of Botrytis cinerea, Alternaria alternata, and Fusarium oxysporum was not affected.

Mechanoenzymatic Breakdown of Chitinous Material to N‐Acetylglucosamine: The Benefits of a Solventless Environment

“…Our early attempts at reacting untreated biomass with chitinases under solventless conditions showed negligible hydrolysis (Figure S9 A in the Supporting Information). First, we suspected that the high CaCO 3 content of the biomass (pH≈8) might impact hydrolysis by increasing the pH beyond the level tolerated by A. niger chitinase . To verify this hypothesis, chitinase activity was tested on a mixture of chitin supplemented with 40 % ( w / w ) CaCO 3 ; an approximately 50 % reduction in the rate of hydrolysis was observed compared with the reaction on chitin alone (Figure S9 B in the Supporting Information).…”

“…[46] The effective chitin loading under these conditions was 400 mg mL À1 ,w hichi s, to the best of our knowledge,2 -8times highert han the most concentrated chitinase reactions reported. [16,22,47] Replacing water with ap H6.0 sodium phosphate buffer (preferred buffer for this enzyme) [57] had an egligible effect on the activity ( Figure S2 Bi nt he Supporting Infor-mation). No hydrolysis was observed in the absence of water, without enzyme, or with inactivated enzyme ( Figure S2 Ci n the Supporting Information).…”

Culturable endophytic bacterial communities associated with field-grown soybean

“…). Brzezinska and Jankiewicz (), assessing a chitinase produced by Aspergillus sp. found that the chitinase inhibited the growth in vitro of Fusarium culmorum , Fusarium solani and Rhizoctonia solani .…”

Effect of olive mill wastewater on growth and bulb production of tulip plants infected by bulb diseases

“…Infection of bulbs with B. tulipae + A. niger, did not cause plant malformations or PH and FM reduction, probably because of the production of antifungal substances by A. niger (Moreno et al, 2003;Brzezinska & Jankiewicz, 2012) and/or antagonism between the two fungi. The mold Aspergillus giganteus is known to produce and secrete a basic low molecular weight protein, the antifungal protein (AFP).…”