Abstract
Bacillus bacteria are advantageous antagonistic organisms that can be used as bio-control agents. This study is aimed at screening the antagonistic activity of different strains of isolated Bacillus bacteria and molecular identification of the superior chitinase producer strain against dermatophytes fungi. Soil samples were collected from different places of Kotoor city, Gharbia Governorate, Egypt and Al Madina Al Munawwarah, Kingdom of Saudi Arabia. A collection of Bacillus isolated from soil was tested in vitro against the dermatophytes: Microsporum sp. and Trichophyton sp. The bacterial strains Kh-B1 and Kh-B2 showed the highest antagonistic activity against dermatophytes pathogenic fungi. The highest amount of chitinase productivity (13.6 units/ml) was obtained from the original Bacillus strain (Kh-B1) at 3 days of incubation. BLAST analysis of the amplified 16S ribosomal RNA gene sequence identified the Bacillus strain (Kh-B1) as Paenibacillus macerans. Upon the mutation induction by UV light, the highest chitinase-producing mutant was Kh-UVB-4 as it showed 305.88 percent production higher than the wild-type strain. While, upon the mutation induction by EMS, the highest amount of chitinase produced was 54.8 units/ml by mutant Kh-ESB-20, and it has produced 402.94% more than the original untreated strain. The application of RAPD-PCR protocol using three 15-mer random primers was used to determine the genetic effects of mutagenic treatments on the wild type strain (Kh-B1) as well as to demonstrate the genetic variability between the five most chitinase producing mutants and the wild type (Paenibacillus macerans).
Highlights
The Bacillus genus is a diverse group ofGram-positive bacteria, facultatively anaerobic, endospore-forming rod-shaped bacteria that involves both extremophiles and mesophiles.[1]
The application of random amplified polymorphic deoxyribonucleic acid (RAPD)-polymerase chain reaction (PCR) protocol using three 15-mer random primers was used to determine the genetic effects of mutagenic treatments on the wild type strain (Kh-B1) as well as to demonstrate the genetic variability between the five most chitinase producing mutants and the wild type (Paenibacillus macerans)
Several studies have confirmed that Bacilli have efficient antimicrobial activity among the soil bacteria,[37,38,39] Inconsistently with our results, a study from India showed the antimicrobial potential of Bacillus subtilis.[40]
Summary
Gram-positive bacteria, facultatively anaerobic, endospore-forming rod-shaped bacteria that involves both extremophiles and mesophiles.[1] the generally accepted natural reservoir for these bacteria is soil, still they are usually spread into the environment.[1] Metabolically these microorganisms are chemo-organotrophs and are reliant on organic compounds as sources of carbon and energy.[2] Bacillus spp. is regarded as remarkable bio-control agent because of its ability to produce high resistant endospores which are usually resistant to different and acute environmental stress.[3,4] By dint of their pervasiveness in nature, and metabolic and genetic diversity driving the production of several antibiotics and enzymes, Bacillus sp. Several studies have reported that Bacillus spp. restrict the growth of numerous plant pathogens by their antagonistic characteristics, with different modes of action like production of enzymes (chitinase and β 1,3-glucanase) and antibiotics (fengycin, surfactin, and iturin) that degenerate antifungal agents and fungal polymers as reported by.[5,6,7]
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