Optimization of Surfactin Production by Bacillus subtilis
Isolate BS5
A. Mohammad Abdel-Mawgoud
&
M. Mabrouk Aboulwafa
&
Nadia Abdel-Haleem Hassouna
Received: 17 October 2007 / Accepted: 15 January 2008 /
Published online: 29 February 2008
#
Humana Press 2008
Abstract Bacillus subtilis BS5 is a soil isolate that produces promising yield of surfactin
biosurfactant in mineral salts medium (MSM). It was found that cellular growth and
surfactin production in MSM were greatly affected by the environmental fermentation
conditions and the medium components (carbon and nitrogen sources and minerals).
Optimum environmental conditions for high surfactin production on the shake flask level
were found to be a slightly acidic initial pH (6.5–6.8), an incubation temperature of 30°C, a
90% volumetric aeration percentage, and an inoculum size of 2% v/v. For media
components, it was found that the optimum carbon source was molasses (160 ml/l),
whereas the optimum nitrogen source was NaNO
3
(5 g/l) and the optimum trace elements
were ZnSO
4
·7H
2
O (0.16 g/l), FeCl
3
·6H
2
O (0.27 g/l), and MnSO
4
·H
2
O (0.017 g/l). A
modified MSM (molasses MSM), combining the optimum medium components, was
formulated and resulted in threefold increase in surfactin productivity that reached 1.12 g/l.
No plasmid could be detected in the tested isolate, revealing that biosurfactant production
by B. subtilis isolate BS5 is chromosomally mediated but not plasmid-mediated.
Keywords Surfactin
.
Bacillus
.
Production
.
Optimization
Introduction
Naturally occurring surface-active compounds derived from microorganisms have gained
attention in the past few decades because of their biodegradability, low toxicity, ecologic
acceptability, and ability to be produced from renewable and cheaper substrates [1, 2].
Biosurfactants find applications in the cosmetic, pharmaceutical, and food industries as
emulsifiers, humectants, dispersants, and detergents [3, 4]. Moreover, they are suited for
Appl Biochem Biotechnol (2008) 150:305–325
DOI 10.1007/s12010-008-8155-x
A. M. Abdel-Mawgoud
:
M. M. Aboulwafa (*)
:
N. A.-H. Hassouna
Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University,
Cairo, Egypt
e-mail: maboulwafa@yahoo.com