Abstract
One hundred and sixty nine Nocardia isolates were recovered from 111 Iraqi soil samples on six cultivation media, using paraffin baiting and dilution techniques. The North of Iraq soil was the richest in Nocardia. Paraffin baiting technique was more efficient in the isolation of Nocardia than dilution technique. Glucose asparagine agar was more suitable for cultivating Nocardia isolates followed by Sabouraud dextrose agar. All the 169 presumptive Nocardia isolates recovered were subjected to primary screening of antibacterial activity, with 10-55 mm inhibition zones against standard Staphylococcus aureus (NCTC 6571) and 10-38 mm inhibition zones against standard Escherichia coli (ATCC 25922). Eleven isolates with the highest antibacterial activities were selected for chemo-taxonomic studies. These isolates exhibited high similar features of 87-89% with Nocardia brasiliensis. Therefore, it is suggested to give proposed names for these new taxa: Nocardia sp.1, N. sp. 2, N. sp. 3, N. sp. 4, N. sp. 5, N. sp. 6, N. sp. 7, N. sp. 8, N. sp. 9, N. sp. 10 and N. sp. 11. . Key words: Secondary metabolite, Nocardia sp., antimicrobial activity.
Highlights
One hundrred and sixty nine Noca ardia isolate es were reco overed from m 111 Iraqi s soil samples s on six cultivation media, using g paraffin ba aiting and dilution techn niques
Glucose asparagine agar was more e suitable fo or cultivating g Nocardia isolates followed by Sabouraud dextrose agar
Serial decimal dilutions of the supernatant were prepared (El-Nakeeb and LeChevalier, 1962), in which 0.1 ml from each dilution was spread over the surface of six types of media: Glucose asparagine agar (GAA), Sabouraud dextrose agar (SDA), Glycerol agar (GA), Nutrient agar (NA), Yeast extract agar (YEA), modified Czapeks agar (MCA)
Summary
One hundrred and sixty nine Noca ardia isolate es were reco overed from m 111 Iraqi s soil samples s on six cultivation media, using g paraffin ba aiting and dilution techn niques. North of Iraq q soil was the richest in Nocardia a. Paraffin baiting b techn nique was more m efficien nt in the iso olation of No ocardia than n dilution technique. Glucose asparagine agar was more e suitable fo or cultivating g Nocardia isolates followed by Sabouraud dextrose agar. Acttinobacteria, especially e when isolated fro om soil produ uce many important industrial and comme ercial antitum mor age ents, bioactive e metabolites s and enzyme es D cepha-mycin n C was produ uced by Noca ardia lactemdu ura
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