4-chlorothreonine, a herbicidal antimetabolite produced by Streptomyces sp. OH-5093.

extract 0.3%, yeast extract 0.5% and CaCO30.4%, pH 7.0, incubated on a reciprocal shaker (300 rpm) at 27°C for 48hours. The culture broth was transferred into a 500 ml-Erlenmyer flask containing 100ml of the same seed medium, and incubated at 27°C for 48 hours on a rotary shaker (210rpm). Vegetative seed culture (2%, v/v) was transferred into a 30-liter jar fermentor containing 20 liters of a production mediumconsisting of maltose 5.0%, dry yeast 1.5%, Ebios tablets (Asahi Breweries Ltd.) 2.5%, KBr 1.0%, KH2PO4 0.05% and MgSO47H2O 0.05%, pH 7.0 and incubated at 27°C for 96 hours with agitation and aeration. The herbicidal activity was assayed by incubating radish (Rhaphanus sativus L.) seeds and sorghum {Sorghum bicolor Moench) seeds on a defatted cotton piece containing an appropriate amountof a test sample in a test tube (2x10cm) at 27°C for 3 to 4 days under