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Actinomycetes in soil produce various antifungal compounds that may protect crops from anthracnose disease.
An international team of Thai and Japanese researchers has studied the effects of actinomycetes on the growth of Colletotrichum, various species of which cause anthracnose disease in plants. Although Colletotrichum, a pathogenic fungus, is often controlled chemically, this can result in environmental pollution and pesticide-resistant pathogens, prompting the team to investigate non-chemical strategies, including the use of bacteria that can produce antifungal compounds. After determining which actinomycete isolates were most effective against Colletotrichum, the team analyzed these isolates using high performance liquid chromatography. The team was led by Bungonsiri Intra of Mahidol University (Bangkok, Thailand).
Anthracnose disease is caused by various species of Colletotrichum, and affects plants worldwide. According to the authors, because the disease can occur in fruits such as avocado, guava, papaya, mango, and passion fruit, it can destroy anywhere from 10% to 80% of the marketable fruit crop in developing countries, including Thailand, Pakistan, Turkey, and Mexico.
The team isolated more than 300 actinomycetes and tested their ability to inhibit those strains of Colletotrichum that cause anthracnose disease. Although most isolates were active against at least one fungus or yeast, five were determined to be active against all indicator fungi and yeast. Extracts from these five were separated and analyzed by HPLC. The team believes that one of these strains, JF-1, will produce novel bioactive compounds not presently in its database.
Of the 300 actinomycete isolates, 30 were selected from rhizospheric soil to determine the antibacterial capability of the soil in which the plants are grown. The team concluded that the abundance of actinomycetes in the soil ensures its capability to produce various antifungal compounds. The researchers' next step will be to purify these compounds and determine their structure for further analysis and application to anthracnose disease.
The study was published in the April 2011 issue of BMC Research Notes.