A STUDY OF THE BACTERIA ASSOCIATED WITH THE ROOTS OF SUBTERRANEAN CLOVER AND WIMMERA RYE-GRASS

SUMMARY: A study of the bacteria from the surfaces of roots of subterranean clover ( T. subterraneum L.) and Wimmera rye-grass ( L. rigidum Gaud.) revealed that 21 genera were represented among the isolates from clover and 16 genera among those from rye-grass. Bacteria showing branched forms predominated and accounted for 63% of the 151 clover isolates and 78% of the 167 grass isolates. Most of these were identified as Arthrobacter , but from clover a significant proportion were Nocardia -like types. Members of the genera Mycoplana, Micromonospora, Mycobacterium , and Mycococcus were also identified among the branching forms.
Although the soil had been inoculated with effective rhizobia and the clover plants were effectively nodulated only one of the 318 isolates was capable of nodulating subterranean clover. The majority of the isolates were chromogenic and Gram-negative, produced acid from glucose and ammonia from peptone, were catalase-positive and grew best aerobically. Approximately half the isolates liquefied gelatin and produced hydrogen sulphide from peptone.