Identification and characterization of endoglucanases for fungicidal activity in Anabaena laxa (Cyanobacteria)

Abstract

A cyanobacterial strain (Anabaena laxa RPAN8) exhibiting fungicidal activity and β-1,3 and 1,4 endoglucanase activities was selected for identifying the gene(s) involved. Functional analyses of the genomic library revealed that four clones (8, 64, 116, and 248) of RPAN8 exhibited fungicidal activity and induced structural deformities in the cell wall of the growing mycelia of Pythium aphanidermatum. Higher expression of fungicidal and β-1,4 endoglucanase activities, along with low expression of β-1,3 endoglucanase activity, was recorded in two E. coli clones (8 and 64). Clones 8 and 64 exhibited identical sequences while clones 116 and 248 were also similar. Bioinformatic analyses were undertaken only for the two nonidentical clones 8 and 116 which showed open reading frames (ORFs) of 348 (end 1) and 656 amino acid residues (end 2), respectively. The amino acid sequence analyses revealed that the end 1 encoding endoglucanases belonged to peptidase M20 family while end 2 showed significant similarities with several known genes. The putative promoters and ribosomal binding sites were identified and amino acid exchanges were observed in both end 1 and 2. The presence of signal peptides of 24 and 20 amino acid residues respectively revealed the secretory nature of these proteins.

Deciphering the biochemical spectrum of novel cyanobacterium-based biofilms for use as inoculants

“…The end 2 belonging to GH5 family from Anabaena sp. encoded both b-1,3-glucanase and endoglucanase, which has also been characterized (Gupta et al 2011. The production of hydrolytic enzymes and their role in biocontrol have been reported earlier for bacterial strains (Singh et al 1999;Grover et al 2009), but the biofilms developed hold more promise as biocontrol agents against phytopathogenic fungi.…”

“…Antifungal b-1,4-endoglucanases end and end 1 encoded by Calothrix elenkinii (Natarajan et al 2012) and Anabaena sp. (Gupta et al 2011), respectively, were observed to belong to the peptidase M20 family. The end 2 belonging to GH5 family from Anabaena sp.…”

“…In recent years, the production of bioactive compounds/enzymes by cyanobacteria and their role in biocontrol and plant growth promotion have been extensively investigated in laboratory and field conditions (Kulik 1995;Jaiswal et al 2008;Dukare et al 2011 for the first time revealed the activity of hydrolytic enzymes in several Anabaena strains and their correlation with antifungal activity. Chitosanase homologues and microcystin-like compounds were identified in two promising strains, Anabaena laxa and Anabaena Iyengarii, which exhibit fungicidal activity (Prasanna et al 2010a;Gupta et al 2010Gupta et al , 2011Gupta et al , 2012, and a novel antifungal chitosanase (cho) gene belonging to glycoside hydrolase family-3 from Anabaena fertilissima was characterized (Gupta et al 2010). Antifungal b-1,4-endoglucanases end and end 1 encoded by Calothrix elenkinii (Natarajan et al 2012) and Anabaena sp.…”

THIRD GENERATION BIODIESEL PRODUCTION FROM MICROALGAE Phormidium autumnale

“…Additionally, the disaccharides such as sucrose are only used in the pentose phosphate pathway, after a previous hydrolysis that transforms this sugar in monosaccharides, particularly fructose and glucose. Several enzymes, specifically invertase, are involved in these reactions and have been identified in microalgae cultures (Fuchs et al, 1994;Gupta et al, 2011). To further improve bulk oil production, continuous cultivations were performed (Table 2).…”

Improved ethanol production from biomass by a rumen metagenomic DNA fragment expressed in Escherichia coli MS04 during fermentation

“…This cluster has been clearly linked to endo-β-1, 4-glucanases (EC 3.2.1.4) belonging to GH5 family (Aspeborg et al 2012;Gupta et al 2011) that also includes endo-β-1,4-xylanases (EC 3.2.1.8) and β-glucosidases (EC 3.2.1.21) among others. GH5 enzymes are abundant in different ecological niches, which have been evidenced by their frequent identification in various metagenomes studies (Duan and Feng 2010;Hess et al 2011).…”