Abstract
The authors of the article describe the impact of Biological Soil Disinfection (BSD) in the elimination of soil-borne plant pathogens. Soil that has undergone BSD is a suitable ground for the growth of anaerobic bacteria such as two isolated strains from the class Clostridia that produce antifungal enzymes and in so doing control soil-borne plant pathogens. Some species of clostridia are useful in the destruction of pathogens; however, other forms of clostridia such clostridium domicile are pathogenic in nature and cause disease to the host. The pathogen described is F. Oxysporum which is a fungal disease that causes disease in plants such as wilting and the Panama disease of the banana.
Classification of microorganism-
The article summarizes the importance of the clostridia family in the control of soil-borne pathogens. It also gives a description of the species, their classes and their family and the mode of interaction in the soil. This article also the impact of Biological soil disinfestation in providing a conducive environment for the growth of anaerobic bacteria. Gram-positive bacteria such as clostridia have rigid cells that are either anaerobic or aerobic. They were however originally described as spore-forming anaerobic rods. The Fusarium oxysporum is a complex species that are of the Kingdom Fungi, of the Hypocreales family and the Fusarium Genus.
Article Summary
The article describes the mechanisms of the clostridia species in aiding in the elimination o soil-borne pathogens. He article describes a number of studies that have shown the effectiveness of the decomposition of organic matter and the reduction process in anaerobic conditions. It also describes the process of using organic material and plant biomass in BSD treatment as well as molecular analysis of bacterial communities. Additionally, the role played by anaerobic bacteria in BSD treatment is outlined. Further, the article describes the process of fungal cell wall components by the clostridia bacteria.
Pathogen Information
- oxysporum are saprophytic by nature and work by degrading carbohydrate and lignin in soil debris. They are plant endophytes that are considered pervasive and colonies plant roots. They are able to survive in a variety of hosts that include pants and animals from mammals and arthropods. Plants may be able to tolerate limited levels of the pathogen, may have a delayed or immediate response.
Cellular/ structural (in case of viruses) characteristics.
The characteristics of the F. oxysporum include the presence of non-septate microconidia that have short heads. They may also contain chlamydospores with a rough or smooth wall appearance that may be formed individually or with others. In this regard, they are single, lateral and short. This may later develop to form emerged clusters. They occur in slightly curved forms that are slightly curved at the tip.
Susceptibility to antibiotics/ antiviral or antifungals.
Fusarium specie is generally resistant to a majority of the antifungal compounds. They are mostly prevented by the use of nitrate-nitrogen fertilizer Use of fungicides such as carbendazim of the class of benzimidazoles which are aromatic and are six-membered benzene fused. They are considered to be biologically diverse and synthetically versatile.
Mutants deficient in SA-mediated defence were shown to be more susceptible to F. oxysporum. Varying mutants are shown to exhibit differences susceptibility whereby these mutants that were more susceptible are those that possess deficiency in deficient in SA-mediated defence. This may be increased by the delayed use of antifungal therapy. However, because of the lack of the minimum effective concentration and the minimum inhibitory concentration, it is often difficult to gauge the antifungal susceptibility of the pathogen species.
Growth conditions.
The species grows well between the temperatures of 20 to 30°C. They also prefer the existence of t a protein content in the environment. Additionally, they often found in acidic conditions with pH 6.0 for growth and sporulation considered as the optimal value for efficient sporulation and growth in addition to humidity levels above 35% R.H.
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Evasion of the immune system.
The species uses the roots as a point of entry into the plant and interferes with the vessels that conduct water in the plant. The pathogen attacks plants following repotting or at the beginning of the flowering stage. The pathogen first attacks the roots then form a blockage of the vascular vessels. It eventually attacks the sap carrying vessels creating obstructions that deny the upper part of the plant some of its nutrients hand water. The plant attempts to prevent the growth of the fungus by creating blockages that blocking its own cells.
Disease(s) caused symptoms, diagnosis, and therapeutic interventions.
One of the major disease cause by F. Oxiysporum is wilting. The symptoms of wilting include a veil-like clearing on the younger leaves while the older leaves begin to droop. This will also evolve into marginal necrosis, defoliation and eventually plant death. Additionally, the plants affected will often exhibit stunting, which is accompanied by yellowing of leaves. Older plants exhibit symptoms that are often more easily identified between blossoming and maturation of fruits. The diagnosis of the diseases is made through restriction fragment length polymorphism (RFLP) analysis. The therapeutic interventions involve antifungal therapy that includes biological fungicides.
References
Heinlen, L., & Ballard, J. D. (2010). Clostridium difficile infection. The American journal of the medical sciences, 340(3), 247–252. https://doi.org/10.1097/MAJ.0b013e3181e939d8
Tonna I, Welsby PDPathogenesis and treatment of Clostridium difficile infectionPostgraduate Medical Journal 2005;81:367-369.