The identification of antibacterial compounds for the development of enhanced media for the detection of foodborne fungi

In an effort to identify a more suitable antibiotic for utilization in mycological media, 12 food borne fungal species from various genera including Alternaria alternata, Aspergillus flavus, A. niger, Eurotium chevalieri, Fusarium moniliforme, Penicillium sp., Rhizopus stolonifer, Saccharomyces cerevisiae, Candida tropicalis, Geotrichum candidum, Rhodotorula glutinis and Kluyveromyces thermotolerans along with 21 chloramphenicol-resistant bacterial isolates from fresh produce and ATCC cultures of Pseudomonas aeruginosa, P. fluorescens, E. coli, Pectobacterium carotovorum, Bacillus cereus and Staphylococcus spp. were tested for their abilities to grow on dichloran rose bengal agar containing various levels of gentamicin, chlortetracycline or chloramphenicol. Results indicated that all fungal isolates except for Rh. glutinis and R. stolonifer grew well on all media tested. Rh. glutinis did not grow on media containing gentamicin whereas R. stolonifer produced very restricted or no growth on these media. All bacterial isolates from fresh produce, P. aeruginosa (ATCC 27853) and P. fluorescens (ATCC BAA-477) grew well at 100, 125 and 150 mg chloramphenicol/liter medium, but they did not grow on media containing chlortetracycline (100, 125, or 150 mg/L) or gentamicin (15, 25, or 35 mg/L). P. aeruginosa (ATCC 10145) grew well on media containing chloramphenicol or gentamicin, but not in the presence of chlortetracycline. P. carotovorum, E. coli, B. cereus and Staphylococcus spp. did not grow on any of the selective media tested.