Antagonistic bacteria are a type of microorganism that produce substances or exhibit behaviours that inhibit the growth or activity of other microorganisms. These bacteria can be found in a variety of environments, including soil, water, and the human body.
The predation of bacteria by other bacteria is an antagonistic relationship that is rarely taken into account. Most frequently, fungi or bacteria are the microorganisms that remove or destroy diseases or insects. They are referred to as antagonists, microbial insecticides or biopesticides. These are a few examples of often utilized antagonistic microorganisms.
Introduction and History:
Since the 1960s, bacteria like Bacillus thuringiensis have been sold as commercial microbial insecticides. Different strains of Bacillus thuringiensis have been used to control caterpillars, beetles, mosquitoes and black flies in vegetables and other farming goods. The bacteria Bacillus thuringiensis var. Aizawa and Bacillus thuringiensis var. Aizawa is the most well-known biocontrol agent used in field crops to combat mosquitoes and other lepidopteran pests.
A decline in the diversity of soil organisms leads to an increase in soil-borne diseases. A soil’s ability to fight against disease will be strengthened by introducing beneficial organisms that fight off, withstand, or prevent disease-causing pathogens. Plants grown in soil that inhibits illness have far superior disease resistance than those grown in soil with little biological variety. Beneficial organisms can be directly introduced, or the soil environment can be improved by using compost and other organic additions.
The effectiveness of compost at controlling soil-borne plant diseases depends on its quality. Laboratory tests can be used to evaluate the quality of compost. Some plant materials are poisonous to insects. These substances are known as botanical pesticides when they are harvested from the plants and used on affected crops. Plant extracts have long been used to eradicate pests. There has been extensive use of tobacco, rotenone (Derris sp), and pyrethrins (Chrysanthemum sp.) in both small-scale subsistence farming and commercial agriculture.
When a pathogen that causes disease and a susceptible host come together in a favourable environment, plant diseases develop. There would not be illness if these three requirements were not satisfied. Several treatment methods (fungicides, methyl bromide fumigants, etc.) focus on getting rid of the pathogen once the effects of the illness are visible. Plant diseases can happen in nature, but they seldom spread widely and cause serious problems. On the contrary, there is always a risk of disease epidemics affecting crop production.
Although agriculture continues to mine soil organic matter and kill fungus by ploughing, the soil organisms utilize the organic matter that they “put away” during the years when disturbance did not occur. The biggest predators are destroyed, and their houses are crumpled. Huge volumes of the organic materials from the savings account are blown off by the bacteria during their bloom. The organisms that combat and stop illness are lost with continued ploughing. The “builders” who construct soil aggregates have vanished.
The larger organisms that plan and create the bigger pores in the soil are also engineers. Losses occur in the predators that keep bacteria, fungi and root-feeding organisms in check.
Because mineral crusts form, disease suppression falls, soil structure erodes, and water infiltration declines. It can take between 20 and 30 years for the decline to reach the point where the majority of the natural controls are eventually eliminated and disease runs out of control. The amount of soil organic matter present when the soil was first ploughed, how frequently it was ploughed, and how much residue was added back all affect how quickly the “edge” is reached. Because the sickness hasn’t yet spread there, some locations don’t experience certain ailments.
However, as soon as the disease does appear, it spreads rapidly over the fields due to a lack of natural competitors in the soil.
Growers have resorted to using newer and more potent chemicals to eradicate problematic infections as plants and soils have become sicker. Even though it can seem sensible, pharmaceutical intervention simply makes problems worse in the long run. Many insecticides further limit the diversity of soil life and favour diseases with resistance. When used just once every five years, this fumigant was once exceedingly effective.
A new, stable balance of soil organisms that will be adapted to the changing soil conditions, replacing the existing, natural, undisturbed balance of organisms. We are moving towards the targeted result of disease prevention with our proactive method.
Disease Suppressive Soils
Suppressiveness is influenced by the kinds and numbers of soil organisms, soil fertility, and soil properties (such as drainage and texture). There are several methods by which disease organisms are suppressed in these soils, including induced resistance, direct parasitism (one organism eating another), nutritional competition, and direct suppression through antibiotics secreted by beneficial species.
Additionally, Suppressiveness is influenced by how soil-based plants react. When a less pathogenic pathogen is introduced to the rhizosphere (soil around plant roots), This condition is referred to as “induced resistance.”. The plant gains the ability to respond effectively to a more virulent disease in the future after being tested by the weak pathogen. Most of the time, fertilizing soil with mature compost causes. The pathogenic fungus Rhizoctonia is encircled by hyphae of the helpful fungus Trichoderma.
Approaches for Control:
Specific and General disease suppression are the two different types.
Specific suppression:
Effects of one organism immediately combating an acknowledged pathogen. In these circumstances, a biological control agent is specifically put into the soil to reduce the incidence of disease.
General suppression:
A result of a wide variety of microbial communities that create settings that stop plant diseases from developing. A method used to manage Rhizoctonia solani, the unity of the plants that cause damping off, is a good illustration of targeted suppression. Rhizoctonia destroys young seedlings when it exists under chilly, moist soil conditions.
Through a substance secreted by the infection, the helpful fungus Trichoderma locates Rhizoctonia and then fights it. The pathogen is entangled by helpful fungal threads (hyphae), which before declaration enzymes kill Rhizoctonia cells by dehydrating them. Trichoderma values are currently offered as biological seed dealings for thwarting disease in several crops.
1Hafiz M Rizwan Mazhar, 2Muhammad Ehetisham Ul Haq
1Nuclear Institute of Agriculture and Biology (NIAB), Faisalabad
2Ayub Agricultural Research Institute, Faisalabad
