A dye-decolorizing peroxidase from Bacillus subtilis exhibiting substrate-dependent optimum temperature for dyes and β-ether lignin dimer

Abstract

In the biorefinery using lignocellulosic biomass as feedstock, pretreatment to breakdown or loosen lignin is important step and various approaches have been conducted. For biological pretreatment, we screened Bacillus subtilis KCTC2023 as a potential lignin-degrading bacterium based on veratryl alcohol (VA) oxidation test and the putative heme-containing dye-decolorizing peroxidase was found in the genome of B. subtilis KCTC2023. The peroxidase from B. subtilis KCTC2023 (BsDyP) was capable of oxidizing various substrates and atypically exhibits substrate-dependent optimum temperature: 30°C for dyes (Reactive Blue19 and Reactive Black5) and 50°C for high redox potential substrates (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid [ABTS], VA, and veratryl glycerol-β-guaiacyl ether [VGE]) over +1.0 V vs. normal hydrogen electrode. At 50°C, optimum temperature for high redox potential substrates, BsDyP not only showed the highest VA oxidation activity (0.13 Umg−1) among the previously reported bacterial peroxidases but also successfully achieved VGE decomposition by cleaving Cα-Cβ bond in the absence of any oxidative mediator with a specific activity of 0.086 Umg−1 and a conversion rate of 53.5%. Based on our results, BsDyP was identified as the first bacterial peroxidase capable of oxidizing high redox potential lignin-related model compounds, especially VGE, revealing a previously unknown versatility of lignin degrading biocatalyst in nature.

Characterization of Dye-decolorizing Peroxidase (DyP) from Thermomonospora curvata Reveals Unique Catalytic Properties of A-type DyPs

“…The results indicate that only the phenolic compound 1 could be depolymerized in the absence of redox mediators, which suggests that the low potential phenolic site (⌬E°Ј ϭ 0.6 -0.8 V) (40) is required for enzyme activity as no degradation of 2 was observed under the same condition. Similar results have also been obtained with B-and C-type DyPs (12,13). The incomplete degradation of 1 (retention time at 13.8 min) was due to enzyme instability at pH 3.0 for prolonged time.…”

“…Among the four classes of DyPs, the A-type is studied the least due to its low activity. However, increasing evidence (13,16), including the present report, suggests that A-type DyPs may have potentials in lignin depolymerization.…”

“…Although their physiological substrates are unknown, they have been demonstrated to carry out lignin degradation, albeit with a low activity (11)(12)(13). Analysis of the genome sequence has revealed that DyPs are mostly present in bacteria, whereas only a limited number exists in fungi and higher eukaryotes (14).…”

Enantioselective Synthesis of Dilignol Model Compounds and Their Stereodiscrimination Study with a Dye-Decolorizing Peroxidase

“…1–3 They have been reported to degrade phenolic lignin model compounds and wheat straw lignocellulose, though the efficiency is low. 4–7 Our interest in DyPs stems from their potential applications in lignin degradation, 8, 9 a critical step in converting lignocellulose biomass to biofuels. 8, 10–13 Lignin biosynthesis produces a β-O-4 interunit linkage up to 50–65% with α and β carbons exhibiting ( R,R ), ( R,S ), ( S,R ), and ( S,S ) stereochemistry.…”

Improved catalytic activities of a dye-decolorizing peroxidase (DyP) by overexpression of ALA and heme biosynthesis genes in Escherichia coli

“…A new family of heme peroxidase was recently discovered and classified as the dye-decolorizing peroxidase-type (DyP-type) family [7]. This group of enzymes degrades various dyes, including of xenobiotic and recalcitrant compounds, rendering them useful for biotechnological applications, particularly in waste treatments [8][9][10]. DyPs are naturally found in several fungal and bacterial species, and rapid progress has been made for recombinant DyP production using heterologous expression hosts [11,12].…”