Comparative Study between Exogenously Applied Plant Growth Hormones versus Metabolites of Microbial Endophytes as Plant Growth-Promoting for Phaseolus vulgaris L.

Microbial endophytes organize symbiotic relationships with the host plant, and their excretions contain diverse plant beneficial matter such as phytohormones and bioactive compounds. In the present investigation, six bacterial and four fungal strains were isolated from the common bean (Phaseolus vulgaris L.) root plant, identified using molecular techniques, and their growth-promoting properties were reviewed. All microbial isolates showed varying activities to produce indole-3-acetic acid (IAA) and different hydrolytic enzymes such as amylase, cellulase, protease, pectinase, and xylanase. Six bacterial endophytic isolates displayed phosphate-solubilizing capacity and ammonia production. We conducted a field experiment to evaluate the promotion activity of the metabolites of the most potent endophytic bacterial (Bacillus thuringiensis PB2 and Brevibacillus agri PB5) and fungal (Alternaria sorghi PF2 and, Penicillium commune PF3) strains in comparison to two exogenously applied hormone, IAA, and benzyl adenine (BA), on the growth and biochemical characteristics of the P. vulgaris L. Interestingly, our investigations showed that bacterial and fungal endophytic metabolites surpassed the exogenously applied hormones in increasing the plant biomass, photosynthetic pigments, carbohydrate and protein contents, antioxidant enzyme activity, endogenous hormones and yield traits. Our findings illustrate that the endophyte Brevibacillus agri (PB5) provides high potential as a stimulator for the growth and productivity of common bean plants.

The Dual Carboxymethyl Cellulase and Gelatinase Activities of a Newly Isolated Protein from Brevibacillus agri ST15c10 Confer Reciprocal Regulations in Substrate Utilization

A protein showing endoglucanase-peptidase activity was prepared from a newly isolated bacterium (ST15c10). We identified ST15c10 as <i>Brevibacillus agri</i> based on electron-microscopic images and its 16S-rDNA sequence (GenBank accession No. HM446043), which exhibits 98.9% sequence identity to <i>B. agri </i>(KZ17)/<i>B. formosus </i>(DSM-9885T)/<i>B. brevis</i>. The enzyme was purified to homogeneity and gave a single peak during high-performance liquid chromatography on a Seralose 6B-150 gel-matrix/C-18 column. MALDI-TOF mass-spectrometry and bioinformatics studies revealed significant similarity to M42-aminopeptidases/endoglucanases of the CelM family. These enzymes are found in all <i>Brevibacillus</i> strains for which the genome sequence is known. ST15c10 grows optimally on carboxymethyl cellulose (CMC)-gelatin (40°C/pH 8-9), and also shows strong growth/carboxymethyl cellulase (CMCase) activity in submerged bagasse fermentation. The purified enzyme also functions as endoglucanase with solid bagasse/rice straw. Its CMCase activity (optimal at pH 5.6 and 60°C/K_m = 35.5 µ<smlcap>M</smlcap>/V_max = 1,024U) was visualized by zymography on a CMC-polyacrylamide gel, which provided a strong band of approximately 70 kDa. The purified enzyme also showed strong peptidase (gelatinase) activity (pH 7.2/40°C during zymography on 6-12% gelatin/1% gelatin-PAGE (at approx. 70 kDa). The CMCase activity is inhibited by the metal ions Mn/Cu/Fe/Co (50%), Hg/KMnO₄ (100%), and by glucose or lactose (50-75%; all at 1 m<smlcap>M</smlcap>). The observed dose/time-dependent inhibition by Hg ions could be prevented with 2-mercaptoethanol. A comparison of the <i>B. agri</i> endoglucanase-aminopeptidase (ELK43520; 350 aa) with other members of the M42-family revealed the conservation of active-site residues Cys256/Cys260, which were previously identified as metal-binding sites. Regulation of the endoglucanase activity probably occurs via metal binding-triggered changes in the redox state of the enzyme. Studies on this type of enzyme are of high importance for basic scientific and industrial research.

PRODUKSI PROTEASE ALKALI DAN KERATINASE DARI Brevibacillus agri A-03 TERMOFILIK

ABSTRAK Protease alkaline and keratinase are a group of protease enzym which have important value in detergen industry and skin tannery. Brevibacillus agri A-03 is thermophilic bacteria isolate that comes from Ambayan Sumatera Barat hot spring and has the ability to produce protease and keratinase. The purpose of this research is to get protease alkaline and thermostable keratinase from Brevibacilus agri-A03. thermostable enzym is produced from enzym production enzym that contains kasein and keratin at various medium pH, inoculum incubation temperature and medium type. Enzym activity is measured by modified Walker methode, protein content is measured by Lowry methode. Protease alkaline is produced at exponential phase, maximum at 18th hours of incubation and keratinase is produced at stationer phase, maximum at 22nd hours. Both enzym is produced optimically at medium pH condition 9.0; incubation temperature 55°C, inoculum 5% by using modified Johnvesly and Naik medium with each protease and keratinase specific activity 1.927 and 1.047 U/mg Keywords: Protease alkaline, Keratinase, Thermofilic, Brevibacillus agri A-03