Fungi Isolation

I'm working on fungi isolation for bioactive metabolites search,
nowadays I'm on the isolation stage.

I have four samples of different fungi, these samples are polluted
with bacteria although the cultivation has a concentration of
cephotaxime of 5 micrograms/ml.

I have checked for many possible sources of pollution, I have improved
the manipulation procedures but the pollution still persists.

I would like to know about sterile procedures or antibiotics to
eliminate the bacteria from these samples. I would appreciate any
suggestions and references (papers, books, web sites) on this topic.

Thanks in advance,

Dr. Monica Enamorado
Institute of Biotechnology
National University of San Juan, Argentina