Journal of Methods Microbiological Journal of Microbiological Methods 40 (2000) 99–104 www.elsevier.com / locate / jmicmeth A rapid technique for screening of lovastatin-producing strains of q Aspergillus terreus by agar plug and Neurospora crassa bioassay * M. Sitaram Kumar, Pallapothu Mahendra Kumar, Hemant M. Sarnaik, A.K. Sadhukhan Fermentation Laboratory, Biotechnology R&D, Dr. Reddy’ s Research Foundation, Bollaram Road, Miyapur, Hyderabad – 500 050, India Received 16 August 1999; received in revised form 18 November 1999; accepted 23 November 1999 Abstract The success of strain improvement programme depends on the number of isolates that can be screened after mutagenic treatment. A technique to rapidly screen large number of high-yielding isolates was developed. The ‘agar plug’ method that utilizes the anti-fungal property of lovastatin to produce a zone of inhibition against Neurospora crassa was not only economical but also less labour-intensive. We were able to isolate a high-yielding strain, the productivity of which increased by 138% as compared to the parent strain in the submerged fermentation process.  2000 Elsevier Science B.V. All rights reserved. Keywords: Agar plug; Aspergillus terreus; Bioassay; Lovastatin; Neurospora crassa 1. Introduction phological characteristics and the elimination of unwanted co-metabolites are goals of an industrial Lovastatin (Mevinolin, Monocolin K and strain improvement programme (Vinci et al., 1991).  Mevacor ) a competitive inhibitor of 3-hydroxy-3- Strain improvement studies were carried out through methylglutaryl–coenzyme A reductase (HMG–CoA random mutation and selection of parent strain reductase) is produced by Aspergillus terreus (Al- Aspergillus terreus ATCC 20541. The success of any berts et al., 1980), Monascus ruber (Endo, 1979) and strain improvement programme depends largely on Penicillium species (Endo et al., 1976). Continuous the total number of cultures that could be screened improvement in productivity of an industrial micro- after a mutagenic treatment. In addition to con- organism is essential for the commercial success of a straints on time, some of the other problems faced fermentation process. Improvement in the yield of are lack of manpower and equipment. To date the the required product, maintenance of desired mor- available method for estimation of lovastatin is by HPLC, which is not only tedious and expensive, but there is also a limitation on the number of cultures that can be analyzed by this method. A rapid screening technique that can evaluate large number q of isolates with a fair degree of accuracy and Footnote: Publication No. 110 from DRF. reproducibility, therefore, becomes imperative. A *Corresponding author. Fax: 1 91-40-304-5438. E-mail address: aks drl@usa.net (A.K. Sadhukhan) method of quantitative comparison of the colonies ] 0167-7012 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0167-7012(99)00135-9