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Journal ArticleDOI: 10.1016/J.IJBIOMAC.2021.02.205

An alkaline thermostable laccase from termite gut associated strain of Bacillus stratosphericus.

04 Mar 2021-International Journal of Biological Macromolecules (Elsevier)-Vol. 179, pp 270-278
Abstract: Laccase, an important oxidoreductase, is widely distributed in various organisms. Termites are known to decompose lignocellulose efficiently with the aid of gut microorganisms. However, few laccases have been characterized from termite or its gut microbes. We aimed to screen the strain capable of degrading lignocellulose from fungus-growing termites. In this study, Bacillus stratosphericus BCMC2 with lignocellulolytic activity was firstly isolated from the hindgut of fungus-growing termite Macrotermes barneyi. The laccase gene (BaCotA) was cloned both from the BCMC2 strain and termite intestinal metagenomic DNA. BaCotA was overexpressed in E. coli, and the recombinant BaCotA showed high specific activity (554.1 U/mg). BaCotA was thermostable with an optimum temperature of 70 °C, pH 5.0. Furthermore, BaCotA was resistant to alkali and organic solvents. The enzyme remained more than 70% residual activity at pH 8.0 for 120 min; and the organic solvents such as methanol, ethanol and acetone (10%) had no inhibitory effect on laccase activity. Additionally, BaCotA exhibited efficient decolorization ability towards indigo and crystal violet. The multiple enzymatic properties suggested the presented laccase as a potential candidate for industrial applications. Moreover, this study highlighted that termite intestine is a good resource for either new strains or enzymes.

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Topics: Bacillus stratosphericus (58%), Laccase (55%)
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6 results found


Open accessJournal ArticleDOI: 10.1186/S12934-021-01597-0
Abstract: Uprising fossil fuel depletion and deterioration of ecological reserves supply have led to the search for alternative renewable and sustainable energy sources and chemicals. Although first generation biorefinery is quite successful commercially in generating bulk of biofuels globally, the food versus fuel debate has necessitated the use of non-edible feedstocks, majorly waste biomass, for second generation production of biofuels and chemicals. A diverse class of microbes and enzymes are being exploited for biofuels production for a series of treatment process, however, the conversion efficiency of wide range of lignocellulosic biomass (LCB) and consolidated way of processing remains challenging. There were lot of research efforts in the past decade to scour for potential microbial candidate. In this context, evolution has developed the gut microbiota of several insects and ruminants that are potential LCB degraders host eco-system to overcome its host nutritional constraints, where LCB processed by microbiomes pretends to be a promising candidate. Synergistic microbial symbionts could make a significant contribution towards recycling the renewable carbon from distinctly abundant recalcitrant LCB. Several studies have assessed the bioprospection of innumerable gut symbionts and their lignocellulolytic enzymes for LCB degradation. Though, some reviews exist on molecular characterization of gut microbes, but none of them has enlightened the microbial community design coupled with various LCB valorization which intensifies the microbial diversity in biofuels application. This review provides a deep insight into the significant breakthroughs attained in enrichment strategy of gut microbial community and its molecular characterization techniques which aids in understanding the holistic microbial community dynamics. Special emphasis is placed on gut microbial role in LCB depolymerization strategies to lignocellulolytic enzymes production and its functional metagenomic data mining eventually generating the sugar platform for biofuels and renewable chemicals production.

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Topics: Biorefinery (51%)

3 Citations


Journal ArticleDOI: 10.1007/S10562-021-03753-Y
14 Aug 2021-Catalysis Letters
Abstract: Laccase is a versatile enzyme that plays a major role in the remediation of various environmental pollutants. In this work, a thermo-tolerant halophilic Bacillus aquimaris AKRC02 was isolated from pulp and paper mill waste sludge for efficient laccase production. Various agro-industrial waste residues, including potato peel, banana peel, sawdust, pea peel, wheat bran, orange peel, and rice bran, were screened to produce laccase using a submerged fermentation process. Among these, rice bran supported the maximum laccase production (4.58 U/mL). The optimized environmental conditions (incubation time 120 h; 4.58 U/mL), 35 0C; 6.624 U/mL) and pH 7.0; 10.142 U/mL) and nutritional sources (glucose 1.0%; 14.164 U/mL and peptone 0.5%; 18.124 U/mL) significantly enhanced the laccase production. Purified laccase showed a specific activity and purification fold of 228.34 U/mg and 38.08, respectively. The purified enzyme showed a molecular weight of 65 kDa and high thermal stability at 45 0C for 8 h. In conclusion, the remarkable properties of the newly isolated bacterium may provide a significant opportunity for degrading environmental contaminants, making it an attractive biocatalyst for industrial applications.

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Topics: Banana peel (56%), Laccase (52%), Bran (51%)

3 Citations


Journal ArticleDOI: 10.1016/J.BIORTECH.2021.125468
Abstract: A novel thermostable/halotolerant metagenome-derived laccase (PersiLac2) from tannery wastewater was purified to remove textile dyes in this study. The enzyme was highly active over a wide temperature and pH range and maintained 73.35% of its initial activity after 30 days, at 50 °C. The effect of various metal and organic-solvent tolerance on PersiLac2 showed, retaining greater than 53% activity at 800 mM of metal ions, 52.12% activity at 6 M NaCl, and greater than 44.09% activity at 20% organic solvents. PersiLac2 manifested effective removal of eight different textile dyes from azo, anthraquinone, and triphenylmethane families. It decolorized 500 mg/L of Alizarin yellow, Carmine, Congo red and Bromothymol blue with 99.74–55.85% efficiency after 15 min, at 50 °C, without mediator. This enzyme could practically remove dyes from a real textile effluent and it displayed significant detoxification in rice seed germination tests. In conclusion, PersiLac2 could be useful in future for decolorization/detoxification of wastewater.

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Topics: Triphenylmethane (51%), Anthraquinone (51%), Laccase (50%) ... read more

3 Citations


Journal ArticleDOI: 10.1007/S13199-021-00809-W
28 Sep 2021-Symbiosis
Abstract: This article explores the symbiotic role of microorganisms (bacteria, fungi and protozoans) associated with xylophagous termites. Members of the subfamily Macrotermitinae belonging to the family Termitidae have evolved symbiosis with fungi, which belong to the genus Termitomyces. The function of Termitomyces varies for different termite groups depending on their feeding behaviour. In some termites, the primary function of Termitomyces fungi is the degradation of lignin to its simpler form and to make cellulose available to termites; however, these fungi also serve as nutrient rich food sources to other groups of termites. The subsequent breakdown of ingested cellulose in termite gut is further facilitated and controlled by the action of various groups of enzymes secreted by gut-borne microflora and micro-fauna. Understanding the function, significance and management of these diverse microbial symbionts associated with pestiferous higher termites may help in developing their effective bio-control.

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Topics: Termitomyces (72%), Macrotermitinae (62%), Termitidae (60%)

2 Citations


Open accessJournal ArticleDOI: 10.3390/IJMS222111755
Guotao Mao1, Kai Wang1, Fangyuan Wang1, Hao Li1  +5 moreInstitutions (1)
Abstract: Laccases can catalyze the remediation of hazardous synthetic dyes in an eco-friendly manner, and thermostable laccases are advantageous to treat high-temperature dyeing wastewater. A novel laccase from Geothermobacter hydrogeniphilus (Ghlac) was cloned and expressed in Escherichia coli. Ghlac containing 263 residues was characterized as a functional laccase of the DUF152 family. By structural and biochemical analyses, the conserved residues H78, C119, and H136 were identified to bind with one copper atom to fulfill the laccase activity. In order to make it more suitable for industrial use, Ghlac variant Mut2 with enhanced thermostability was designed. The half-lives of Mut2 at 50 °C and 60 °C were 80.6 h and 9.8 h, respectively. Mut2 was stable at pH values ranging from 4.0 to 8.0 and showed a high tolerance for organic solvents such as ethanol, acetone, and dimethyl sulfoxide. In addition, Mut2 decolorized approximately 100% of 100 mg/L of malachite green dye in 3 h at 70 °C. Furthermore, Mut2 eliminated the toxicity of malachite green to bacteria and Zea mays. In summary, the thermostable laccase Ghlac Mut2 could effectively decolorize and detoxify malachite green at high temperatures, showing great potential to remediate the dyeing wastewater.

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Topics: Laccase (58%), Malachite green (57%)

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73 results found


Open accessJournal ArticleDOI: 10.1111/J.1574-4976.2005.00010.X
Abstract: Laccases of fungi attract considerable attention due to their possible involvement in the transformation of a wide variety of phenolic compounds including the polymeric lignin and humic substances. So far, more than a 100 enzymes have been purified from fungal cultures and characterized in terms of their biochemical and catalytic properties. Most ligninolytic fungal species produce constitutively at least one laccase isoenzyme and laccases are also dominant among ligninolytic enzymes in the soil environment. The fact that they only require molecular oxygen for catalysis makes them suitable for biotechnological applications for the transformation or immobilization of xenobiotic compounds.

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Topics: Laccase (64%)

1,743 Citations


Journal ArticleDOI: 10.1016/J.TIBTECH.2006.03.006
Abstract: Laccases are oxidoreductases belonging to the multinuclear copper-containing oxidases; they catalyse the monoelectronic oxidation of substrates at the expense of molecular oxygen. Interest in these essentially ‘eco-friendly' enzymes – they work with air and produce water as the only by-product – has grown significantly in recent years: their uses span from the textile to the pulp and paper industries, and from food applications to bioremediation processes. Laccases also have uses in organic synthesis, where their typical substrates are phenols and amines, and the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. Here, we provide a brief discussion of this interesting group of enzymes, increased knowledge of which will promote laccase-based industrial processes in the future.

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Topics: Laccase (64%)

998 Citations


Open accessJournal ArticleDOI: 10.1128/MMBR.63.1.1-20.1999
Adam Driks1Institutions (1)
Abstract: In response to starvation, bacilli and clostridia undergo a specialized program of development that results in the production of a highly resistant dormant cell type known as the spore. A proteinacious shell, called the coat, encases the spore and plays a major role in spore survival. The coat is composed of over 25 polypeptide species, organized into several morphologically distinct layers. The mechanisms that guide coat assembly have been largely unknown until recently. We now know that proper formation of the coat relies on the genetic program that guides the synthesis of spore components during development as well as on morphogenetic proteins dedicated to coat assembly. Over 20 structural and morphogenetic genes have been cloned. In this review, we consider the contributions of the known coat and morphogenetic proteins to coat function and assembly. We present a model that describes how morphogenetic proteins direct coat assembly to the specific subcellular site of the nascent spore surface and how they establish the coat layers. We also discuss the importance of posttranslational processing of coat proteins in coat morphogenesis. Finally, we review some of the major outstanding questions in the field.

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539 Citations


Journal ArticleDOI: 10.1038/NRMICRO3182
Andreas Brune1Institutions (1)
Abstract: Termites depend on an intricate symbiosis with flagellated protists, archaea and bacteria in their guts for the digestion of lignocellulose. Here, Andreas Brune gives an overview of the diversity of the termite microbiota and highlights important microbial processes in the gut microecosystem and their implications for host nutrition.

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519 Citations


Open accessJournal ArticleDOI: 10.1074/JBC.M200827200
Abstract: The Bacillus subtilis endospore coat protein CotA shows laccase activity. By using comparative modeling techniques, we were able to derive a model for CotA based on the known x-ray structures of zucchini ascorbate oxidase and Cuprinus cereneus laccase. This model of CotA contains all the structural features of a laccase, including the reactive surface-exposed copper center (T1) and two buried copper centers (T2 and T3). Single amino acid substitutions in the CotA T1 copper center (H497A, or M502L) did not prevent assembly of the mutant proteins into the coat and did not alter the pattern of extractable coat polypeptides. However, in contrast to a wild type strain, both mutants produced unpigmented colonies and spores unable to oxidize syringaldazine (SGZ) and 2'2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The CotA protein was purified to homogeneity from an overproducing Escherichia coli strain. The purified CotA shows an absorbance and a EPR spectra typical of blue multicopper oxidases. Optimal enzymatic activity was found at < or =pH 3.0 and at pH 7.0 for ABTS or SGZ oxidation, respectively. The apparent K(m) values for ABTS and SGZ at 37 degrees C were of 106 +/- 11 and 26 +/- 2 microm, respectively, with corresponding k(cat) values of 16.8 +/- 0.8 and 3.7 +/- 0.1 s(-1). Maximal enzyme activity was observed at 75 degrees C with ABTS as substrate. Remarkably, the coat-associated or the purified enzyme showed a half-life of inactivation at 80 degrees C of about 4 and 2 h, respectively, indicating that CotA is intrinsically highly thermostable.

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Topics: Endospore coat (61%), Multicopper oxidase (52%), Bacillus subtilis (52%) ... read more

477 Citations


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