Characterization of Bacillus Strains Producing Biosurfactants - Environmental Sustainability: Role of Green Technologies - page 165

molasses, whey, starch wastes, cassava-fl our
processing effl uent, and distillery waste (Makkar
and Cameotra 2002 ; Deleu and Paquot 2007 ).
Value-added products or benefi ts can improve
the economics of such bioprocesses, including
microbial waste reduction.
Due to the high interest in biosurfactants for
application in a variety of fi elds, the molecular
mechanisms of regulation of the expression of
the operons responsible for LPs as well as identi-
fi cation of genes responsible for their synthesis
have been studied (Jacques 2011 ). The purpose
of the chapter is to provide a comprehensive
overview of the results from our studies on
identifi cation, characterization, and assessment
ability of three Bacillus strains to produce bio-
surfactants, and detection of genes encoding
enzymes involved in biosurfactant synthesis.
Moreover, the use of alternative substrates to
decrease the cost of LP biosurfactant production
and some aspects of Bacillus spp. application as
biocontrol agents are also discussed.

1 Introduction

Genus Bacillus encompasses a Gram-positive,
endospore-forming, rod-shaped bacteria, obligate
aerobes, or facultative anaerobes. The bacilli
includes species of industrial, biotechnological,
and environmental interest, as well as clinically
important strains. Members of genus Bacillus are
widely distributed in the environment and have
ecological importance. Since this group encom-
passes closely related strains, their identifi cation
can be diffi cult. Therefore, the use of a combi-
nation of biochemical, metabolic, and molecular
methods is required for accurate discrimination.
In terms of metabolic properties, they present a
diverse group, as they can degrade various sub-
strates and produce many molecules, including
lipopeptide (LP) biosurfactants, compounds
composed of cyclic peptides linked to various fatty
acids. Since this group of biosurfactants exhibits,
besides the surface active properties, antibacterial,
antifungal, antiviral, and antitumor activities, they
are commonly used in agriculture, food produc-
tion, chemistry, cosmetics, pharmaceutics, and
environmental biotechnology. Biosurfactants
have numerous benefi cial qualities: they can be
non-toxic, non-hazardous, biodegradable, envi-
ronmentally friendly, selective, and effective
under extreme conditions, and have numerous
industrial applications and unique surface-active
properties. In spite of these benefi cial properties,
their higher production cost compared with
synthetic surfactants is a major drawback.
Biosurfactants could potentially replace synthetic
surfactants if the cost of their production were to
be substantially lowered. The best way to reduce
substrate costs for biotechnology at present is to
use recycled agricultural material with the right
balance of nutrients to support microbial growth
and biosurfactant production for environmental
applications. So far, several renewable substrates,
including various agricultural and industrial
by-products and waste materials, have been
intensively studied for microorganism cultivation
and biosurfactant production at the laboratory
scale. These include olive oil mill effl uent,
waste frying oil, oil refi nery wastes, soapstock,

2 Genus Bacillus

Genus Bacillus encompasses a gram-positive,
endospore-forming, rod-shaped bacteria, obli-
gate aerobes, or facultative anaerobes. The fi rst
classifi cations of Bacillus species were based on
two characteristics: aerobic growth and endo-
spore formation. This resulted in linking together
many bacteria possessing different kinds of
physiology, ecology, and genetics, making it
diffi cult to categorize the genus Bacillus or to
make generalizations about it. Subsequently,
numerical classifi cation based on a series of
phenetic characters has been used for the clas-
sifi cation of 368 Bacillus strains into 79 clusters
(Priest et al. 1988 ). At about the same time, ribo-
somal DNA (rDNA) sequences were being estab-
lished as a very useful molecular marker to infer
phylogenetic relationships and, after 1990, 16S
rDNA sequence alignment has been successfully
applied in determining phylogenetic relationships
of Bacillus species. Now, based on the genetic
approach, genus Bacillus belongs to the division
Firmicutes , order Bacillales , and the family