Comparison of 5.8S and ITS2 rDNA RFLP patterns among isolates of Acremonium obclavatum, A. kiliense, and A. strictum from diverse sources.

Polymerase chain reaction (PCR) products of nuclear 5.8S and internal transcribed spacer regions (ITS2) of rDNA from reference cultures of Acremonium obclavatum (a rarely recognized species first reported from India) were compared with cultures of Acremonium spp. isolated from Georgia, USA. Digestion of amplicons sequentially with Hinfl and Sau3AI divided the isolates into four restriction fragment length polymorphism (RFLP) groups. A representative isolate of primary colonizers of insulation facings from a building in Georgia appeared identical to the type culture of A. obclavatum, whereas other cultures from Indian soils showed variation in the ITS2 region that divided them into further subgroups. Reference cultures of A. kiliense (ATCC 14489) and A. strictum (ATCC 10141) and two additional isolates from metropolitan Atlanta, assigned to this latter species complex on a morphological basis, represented two additional RFLP groups both of which were distinct from the RFLP groups in A. obclavatum. A. kiliense and A. strictum could be placed into similar subgroups on the basis of morphological differences and distinct RFLP patterns.