Universidade Católica Portuguesa. Escola Superior de Biotecnologia
Abstract
Interest in biosurfactants has increased considerably in recent years, as they are
potential candidates for many commercial applications in the petroleum,
pharmaceuticals, biomedical and food processing industries. Biosurfactants have several
advantages over chemical s urfactants including lower toxicity and higher
biodegradability, and effectiveness at extreme temperatures or pH values. In spite of the
advantages, fermentation must be cost competitive with chemical synthesis and many of
the potential applications that have been considered for biosurfactants depend on
whether they can be produced economically. The use of alternative molasses medium
(sucrose content 20 g/L, supplemented with 3 g/L yeast extract and 5 g/L peptone) for
biosurfactant production by Streptococcus thermophilus A was studied. Suitable models
were established to describe the response of the experiments pertaining to glucose or
sucrose consumption, cell growth and biosurfactant production. Conventional synthetic
M17 broth was used as control experiments. The replacement of M17 broth by cheaper
molasses medium resulted on an increase about 1.4 times in the mass of produced
biosurfactant (mg) per gram cell dry weight and a 80% medium preparation costs
reduction.In con clusion, the results obtained showed that molasses medium can be used
as a relatively inexpensive and economical alternative to conventional synthetic medium
for biosurfactant production by S. thermophilus A