A natural bacterial strain Bacillus pumilus 16: Identification and antibiotic resistance evaluation

Alena N Irkitova,Angelina V Malkova,Dina E Dudnik

doi:10.3897/abs.7.e78412

Abstract

Microbial biopreparations are actively used to prevent, diagnose, and treat infectious, allergic, tumor, and autoimmune diseases in humans and animals; to stimulate the growth and development of plant crops. Natural bacterial strains with valuable technical properties are a vital biological resource for developing new biopreparations and rotating already known microbial preparations in the world market. This study describes a new natural strain B. pumilus 16, which was isolated from the rhizosphere of Cichorium. The strain was identified using morphological and physiological parameters, biochemical tests, and primers Pum-f. and Pum-r. Antibiotic sensitivity and antagonistic activity against Escherichia coli were determined by diffusion of discs and delayed antagonism methods, respectively. The new natural strain (like type strains) fermented arabinose, cellobiose, mannitol, mannose, salicin, sucrose, and trehalose, and gave a positive reaction to arginine dihydrolase, ONPG, Voges-Proskauer test. It also gave a negative reaction to inositol, raffinose, sorbitol, methyl-D-glucoside, inulin, and lecithinase. B. pumilus 16, unlike the test strains, was capable of fermenting citrate. Strain B. pumilus 16 was highly sensitive to cephalexin (37.9&plusmn;0.7 mm) and enrofloxacin (25.7&plusmn;8.9 mm); sensitive to ole-andomycin (17.1&plusmn;1.9 mm), benzylpenicillin (18.5&plusmn;1.2 mm), and monomycin (16.0&plusmn;0.6 mm); resist-ant to oxacillin. By the agar blocks method (7.3&plusmn;1.5 mm), a more pronounced antagonism of the new strain against E. coli was recorded than by the method of agar wells (5.3&plusmn;0.6 mm). Due to the level of antagonistic activity, B. pumilus 16 was more effective than the type strains (two of which did not show an antagonistic effect). On the basis of this, the new strain can be recommended for inclusion in the bacterial preparation composition for the national economy.

Highlights

Biological preparations, including microbial bio preparations, are actively used to prevent, diagnose, and treat an infectious, allergic, tumor, and autoimmune diseases in humans and animals
Solid L-medium obtained by adding agar (15 g /L) to the L-broth was used to assess the purity of bacterial cultures and to study delayed antagonism and antibiotic resistance
Based on the morphology and basic properties corresponding to the genus Bacillus, we obtained 33 bacterial strains from 107 plant samples

Summary

Introduction

Biological preparations, including microbial bio preparations, are actively used to prevent, diagnose, and treat an infectious, allergic, tumor, and autoimmune diseases in humans and animals. Natural bacterial strains with valuable technical properties are a vital biological resource for developing new biopreparations and rotation of already known microbial preparations in the world market. Bacteria of the genus Bacillus are one of the most studied groups of microorganisms. They are widely used in various sectors of the economy (Ruiz-Garcıa et al 2005; Baruzzi et al 2011; Cihan et al 2012). The genus Bacillus belongs to the Firmicutes phylum and includes more than 200 species. Representatives of this taxon are Gram-positive rods, capable of forming endospores (Ten et al 2006; Zeigler and Perkins 2008). They are widespread (Earl et al 2008; Connor et al 2010; Mathew and Krishnamurthy 2018)

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