办事指南

The fungus eaters

点击量:   时间:2019-03-07 06:01:05

By Haim Watzman in Jerusalem THE mould that makes penicillin may be about to gain another role in the battle against disease—this time fighting fungal diseases that afflict crops. Yigal Cohen of Bar-Ilan University in Ramat Gan, Israel, believes waste from penicillin production, which is already used as a fertiliser, also encourages the growth of fungi that compete with pathogenic species Penicillium mould contains large quantities of chitin, the polysaccharide that is the major structural component of fungal cell walls. Spent cultures of the mould are often simply thrown away. However, Biochemie, of Kundl in Austria, a subsidiary of Swiss drugs giant Novartis and one of the world’s major producers of penicillin, markets its waste in four forms as a fertiliser. One of the fertilisers, Biosol, comes as pellets containing extra potassium sulphate. When Cohen added these pellets to soil until they made up one per cent by weight, he found that they suppressed the pathogenic fungi that attack plants’ roots. “Soil-borne diseases, such as Fusarium, which attacks melons, are a major agricultural problem, especially in monocultures,” says Cohen. The problem is all the more acute because methyl bromide, the major treatment for these diseases, is being phased out in industrial countries because it destroys the ozone layer. Cohen suspected that chitinolytic fungi in the pellets were acting on soil pathogens. Unlike most other fungi, these species can digest chitin. To test his theory, Cohen took soil treated with Biosol and placed it in a growth medium of chitin. Fungi quickly appeared in his Petri dishes even though they are normally extremely difficult to culture from samples of soil that has been used for cultivation, Cohen says. Cohen’s next step will be to isolate the varieties of chitinolytic fungi involved and prove that they actively suppress the pathogens. If his hypothesis is correct,