Purification, Characterization, and Biocatalytic and Antibiofilm Activity of a Novel Dextranase from Talaromyces sp.

Abstract

Dextranase is a useful enzyme that catalyzes the degradation of dextran to low-molecular-weight fractions, which have many critical commercial and clinical applications. Endophytic fungi represent a source of both high heat-stable and pH-stable enzymes. In this study, from Delonix regia bark by plate assay, out of 12 isolated fungal strains, hyaline zones were detected in only one strain. By using the standard ITS rDNA sequencing analysis, the isolated strain was identified as Talaromyces sp. In the case of carbon source, in a medium containing 1% dextran T2000 as the sole carbon source, the maximum dextranase activity reached approximately 120 U/ml after incubation of 2 days where the optimum pH was 7.4. Peptone addition to the production medium as a sole nitrogen source was accompanied by a significant increase in the dextranase production. Similarly, some metal ions, such as Fe2+ and Zn2+, increased significantly enzyme production. However, there was no significant difference resulting from the addition of Cu2+. The crude dextranase was purified by ammonium sulfate fractionation, followed by Sephadex G100 chromatography with 28-fold purification. The produced dextranase was 45 kDa with an optimum activity at 37°C and a pH of 7. Moreover, the presence of MgSO4, FeSO4, and NH4SO4 increased the purified dextranase activity; however, SDS and EDTA decreased it. Interestingly, the produced dextranase expressed remarkable pH stability, temperature stability, and biofilm inhibition activity, reducing old-established biofilm by 86% and biofilm formation by 6%.

Proteomics of Streptococcus mutans to Reveal the Antibiofilm Formation Mechanism of Ag/ZnO Nanocomposites with Light-Emitting Diode Radiation

“…The increase in dexA expression can disturb dextran-dependent aggregation in biofilm formation. 33,34 The sucrose consumption decrease directly confirmed the inhibition of sucrose metabolism. With a 24-h culture, synergistic therapy reduced sucrose consumption by approximately half (Figure 6B).…”

“…Herein, we selected 2 metabolism-related proteins, dltC, and dexA, based on their importance in biofilm formation, D-alanine metabolism, and sucrose metabolism. [32][33][34] The transcriptional levels of their corresponding genes were estimated using RT-qPCR, which further validated their up-or downregulated expression. 38,39 Meanwhile, the same RT-qPCR assay was performed to assess the transcriptional level of glucosyltransferase-SI (gtfC).…”

“…Among them, D-alanine-poly(phosphoribitol) ligase (dltC) was in the D-alanine metabolism pathway, while SMU82_04583 and dextranase (dexA) were in the starch and sucrose metabolism pathway. These two pathways were reported to be highly related to biofilm formation.- [32][33][34] Given this importance, we listed the involved GO terms dltC and dexA. dexA was located in the terms metabolic process, catalytic activity, extracellular region, cell, cell part, extracellular region, external encapsulating structure, and extracellular region.…”

“…Furthermore, inhibition of sucrose metabolism and D-alanine metabolism can disturb biofilm formation. [32][33][34] Thus, the expression regulation of dexA and dltC could disturb sucrose metabolism and D-alanine metabolism, which resulted in the antibiofilm formation actions detected in surviving bacteria.…”

Endophytism of Fusarium Solani in Meristems of Delonix Regia (Bojer ex Hook.) Raf.

“…Accordingly, it is imperative to confirm the safeness of metabolites produced by the endophytes also. The exploration of fungal endophytes from Delonix was bounded except few reports from India, southwest China, and Egypt [5][6][7][8].…”