Probiotics With Multiple Functions To Enhance Crop Growth And Health: Bacillus Mycoides (BM)

• category : Other
• date : 2021-05-26
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The United Nations General Assembly announced 2020 as the International Year of Plant Health (IYPH). The goal was to raise global awareness of how protecting plant health can help with several public issues such as hunger, poverty, economic problems, and the environment. In recent years, many types of microorganisms beneficial to crops have been studied worldwide. Most of these microorganisms could promote crop growth; nevertheless, some of them could effectively control crop diseases. In Professor Huang’s Lab, several plant growth-promoting rhizobacteria (PGPR), including Bacillus mycoides (BM), have been isolated from crop root systems. The applications of BM could enhance seedling growth of various plants including tomato, lettuce, edible rape, cabbage and asparagus bean, and could induce resistance against pests and plant pathogens. These applications could produce safe and healthy agricultural products, and reduce the use of chemical pesticides and fertilizers. Application of the BM-derived products could potentially reduce the excessive use of chemical fertilizers and pesticides, could avoid environmental pollutions due to the use of heavy metals and pesticides, and could improve soil productivity. The ultimate goal of developing BM-related products is to preserve and protect agricultural ecosystems, to produce high-quality agricultural products with less environmental damage, and to increase food safety, thus achieving sustainable agriculture.

The United Nations General Assembly announced 2020 as the International Year of Plant Health (IYPH). The protection of plant health is currently an important issue related to many global problems. For example, the Food and Agriculture Organization of the United Nations estimated that 40% of food crop losses were due to plant pests and diseases. Moreover, the excessive use of chemicals in agriculture has damaged the environment. Therefore, a sustainable application for plant health is needed to maintain the harmony of our environment and to solve the global issues at this moment.

Innovations in sustainable agriculture have been developed in recent years. Many types of microorganisms beneficial to crops have been studied worldwide, mainly including Bacillus subtilis, Bacillus mycoides, Pseudomonas fluorescens, Lactic acid bacteria, Streptomyces spp., Trichoderma spp., Gliocladium spp., Glomus spp., and so on. In Professor Huang’s Lab, several beneficial Bacillus mycoides (BM) strains were isolated from crop roots. The abilities of these BM isolates to promote plant growth have been proved under laboratory, greenhouse, and field conditions. Because of the distinct colony morphology on agar plates (Figure 1), B. mycoides is easy to recognize. The morphology of a B. mycoides colony on nutrient agar is like a fungal colony; it grows circularly from inside to outwards, and the direction may be clockwise or counter clockwise in different strains due to different genes.

B. mycoides is a type of plant growth-promoting rhizobacteria (PGPR), which could proliferate and survive in soils, plant roots and tissues. In Dr. Huang’s Lab, exogenous application of these BM isolates has demonstrated their ability to enhance growth of various plants including tomato, lettuce, edible rape, cabbage and asparagus bean, and to induce resistance against pests and plant pathogens (Figure 2). The formulated BM products could promote the growth of cabbage, cucumber, asparagus bean, radish, lettuce, tomato and rice; and could even effectively control tomato Fusarium wilt, cucumber damping off, powdery mildew on tomato and cucumber, strawberry gray mold, cabbage club root, rice blast, scallion rust and strawberry mites.

Dr. Huang’s research focuses not only on the efficacy of BM applications but also on discovering the mode of actions. To uncover the mechanisms of BM application on plant health, his research has demonstrated that the mechanisms underlying plant growth promotion and disease resistance are because of the following:

1. BM could effectively colonize root systems and the inside of plants, and could induce plant defense reactions;
2. BM could produce and secrete the plant growth hormone indole-acetic acid (IAA) to enhance the development of root systems;
3. BM could release dimethyl disulfide (DMDS) and secrete biosurfactins that disrupt pathogens' cell membranes.

The isolates of BM have been developed into bio-pesticides and bio-fertilizers to cultivate healthy seedlings of various crops and control many diseases such as orchid Fusarium yellows, strawberry Fusarium wilt, tomato powdery mildew, cucumber damping off, rice diseases, etc. By uncovering the mode of actions of BM on crops, it will provide a clear picture for future development of bio-pesticides and bio-fertilizers.

The ultimate goal of developing BM-related products is to preserve and protect agricultural ecosystems, to produce high-quality agricultural products with less environmental damage, and to increase food safety. The BM-related products derived from Dr. Huang’s research will promote plant growth by providing the necessary nutrients, and induce plant resistance against a variety of pathogens. Application of the BM-derived products could reduce the excessive use of chemical fertilizers and pesticides, could avoid environmental pollution due to heavy metals and pesticides, and could improve soil productivity. Therefore, agricultural production can be sustained for many generations to come.

Morphology of Bacillus mycoides and its functions for enhancing plant growth and controlling crop diseases

Figure 1. Colony morphology of B. mycoides (BM) on nutrient agar and cells of BM under scanning electron microscope.

Figure 2. A. B. mycoides used for the cultivation of vegetables to promote the growth of crop seedlings (Upper left to lower left: cabbage, asparagus bean, edible rape, lettuce and tomato; right two: BM the cultivation of vegetables with mycoides; left tw

• ： https://trh.gase.most.ntnu.edu.tw/en/article/content/203

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