REPORT ON BACILLUS SUBTILIS
INTRODUCTION
Bacillus subtilis is a gram-positive bacterium. It is saprophytic in nature. Mostly, it has been found that this bacterium exists in the form of spores rather than being biologically active. The ability to form these spores which are referred to as endospores enables them to survive adverse conditions. Some of the B. subtilis are found to be pathogenic for mammals and insects. The habitat of B. subtilis is soil, river and decomposing plant material . B. subtilis can be divided into two major types, one being that which is applied to the foliage of the plant and the other one which is mixed with soil while seeding. The antibiotic it produces gives it an advantage as it kills the other microbes or reduces their growth rate .
ILLNESSES
B. subtilis is not known to cause any illness in humans but is responsible for allergy to skin or hypersensitive reactions for those working in industrial settings and are exposed to the enzyme subtilisin repeatetly which is produced by this bacterium. Toxicological effects were not reported because of this bacterium. Skin or eye irritation may be caused. Although some strains such as B. anthracis and B.sphaericus are pathogenic for mammals and insects. Products of this bacterium are used in agriculture to promote better crop cultivation. It was established by The US EPA Biopesticides and Pollution Prevention Division that B. subtilitis MBI 600 is not known to cause pathogenic effects in birds and insects. It is not harmful to aquatic life and also no impact was observed on ground water .
It has been found in studies that about 4% of B. subtilis genome codes for antibiotic or similar products. It is found that they also produce hormones which enhance plant growth . Antibiotic product called iturins is used to protect plants by applying it to the root zone, foliar and seed. This helps in preventing disease causing organisms that attack the plants. The ways in which the bacterium disrupts such disease causing organisms include inhibition of germination of spore, disruption of the growth of germ tube and also by inhibiting the attachment of the pathogen to the plant. The antibiotic product, iturin is generally activated against fungal infections. Fungus such as Sclerotinia fruticola, Fusarium spp. and Rhizoctonia spp are suppressed by this bacterium .
ENVIRONMENTAL USES
B. subtilis is ubiquitous in nature. They are used as a seed inoculant. They are indicated to enhance the yield of crop. It has been found that B. subtilis is present abundantly in the rhizosphere of various plants at concentrations as high as 107 per gram of rhizosphere soil. Strains of this bacterium have also been found to produce plant growth hormones such as gibberellin and indole-acetic acid. As earlier mentioned they also produce antifungal agents which make them advantageous for plants as they promote their growth and protect them too. This bacterium survives even in adverse conditions as it has the ability to form endospores. There are different strains available that perform different functions. Strain QST713 is a product that is applied to the foliar part of the plant. GB03 and MBI 600 is applied to soil or seed and control the fungi that infects roots. B. subtilis var. amyloliquefaciens strain FZB 24 is applied to the soil . These strains are used widely to protect crops from fungal attack and therefore a high yield is attained. The bacterium because of its non-pathogenic nature is used widely.
Works Cited
Anil Wipat, C. R. (1999). The Bacillus subtilis genome sequence: the molecular blueprint of a soil bacterium. FEMS Microbiology Ecology , 1-9.
Material Fact Sheet Bacillus subtilis . (n.d.). Retrieved March 11, 2016, from Centre for Environmental Farming Systems Website: www.cefs.ncsu.edu> events> sosa2010
