Potential antibiotic-producing fungal strains isolated from pharmaceutical waste sludge

Abstract

Background: Antibiotic resistance and dearth of novel compounds from natural sources warrants the need to search other environments for potential antibiotic-producing microbial species. The study investigated isolation and identification of antibiotic-producing fungi from pharmaceutical waste sludge. Results: Seven hundred and ninety-seven isolates obtained from sludge of seven pharmaceutical industries in Sango Ota, Ogun State using several growth media, with mould isolates highest (696). Isolated species were from genera Aspergillus (28.55%), Penicillium (18.35%), Trichoderma (13.44%), Rhizopus (10.21%) and Geotrichum (4.01%), and Stachybotrys (0.13%). The CFS of strains named Geotrichum candidum OMON-1, Talaromyces pinophilus OKHAIN-12, and Penicillium citrinum PETER-OOA1 had high reproducible bioactivity against Staphylococcus aureus (32 ± 0.12 mm) and Klebsiella pneumoniae (29 ± 0.12 mm) while P. citrinum MASTER-RAA2 had activity against K. pneumoniae only. Active metabolites were successfully extracted using Diaion HP-20 and methanol:iso-propanol:acetone (6:3:1 v/v). Antibacterial-active fractions of fungal extract successfully eluted with 40–60% NaCl on ion-exchange chromatography using a cation column. Conclusions: The study successfully screened antibiotic-producing fungal species from pharmaceutical waste storage facilities. Study also showed that similar species from same toxic environment could potentially produce different metabolites.