204 Chapter 10
ing the shift from aerobic to anaerobic
metabolism as a function of environmental
conditions.
The genome sequencing of S. xylosus is
ongoing, and information can be obtained at
http://www.cns.fr/externe/English/Projets/Projet_
NN/NN.html. Knowledge of the whole chro-
mosome sequence of S. xylosus , whose size
has been estimated to be 2.86 Mb (Dordet -
Frisoni et al. 2007 ), will provide for a better
understanding of the physiology of this
species. A proteomics approach to study
cell - envelope proteins of S. xylosus has been
developed (Planchon et al. 2006, 2007 ), in
which a signifi cant set of cell - enveloped
proteins can be recovered. When such infor-
mation is integrated with future analyses
of the transcripts, a more integrated and com-
prehensive knowledge of the mechanism
by which meat starter bacteria contribute to
the fermentation of meat can be obtained, as
can how these bacteria interact with one
another.Starter Cultures: Technological
Advantage in the Meat
Environment
Competitiveness
To make the ideal starter culture for any par-
ticular technology and recipe, it is necessary
to understand the function we seek and to
have tools to monitor the effi cacy of the
culture (Hansen 2002 ). One of the fundamen-
tal properties of bacterial starter cultures is
the ability to compete with the adventitious
microbiota of meat, to colonize this environ-
ment, and to dominate the microbial com-
munity of the fermented products. The starter
culture must compete with the natural micro-
biota of the raw material and undertake the
metabolic activities expected of being condi-
tioned by its growth rate and survival in the
conditions prevailing in the sausage (i.e., an
anaerobic atmosphere, rather high salt con-
centrations, low temperatures, and low pH).development and stability of the desired red
color of fermented sausages by means of
their nitrate reductase activity (Miralles et al.
1996 ). In addition, they contribute to the
development of other organoleptic properties
such as texture and fl avor (Hammes and
Hertel 1998 ). These functions are accom-
plished by specifi c enzymes involved in the
metabolism of proteins and lipids. Previous
studies have demonstrated that the aroma of
fermented meat products can be modulated
by the presence of different Staphylococcus
spp. (Berdagu é et al. 1993 ; Stahnke 1995 ;
Sondergaard and Stahnke 2002 ).
A deeper view of the technological prop-
erties of S. carnosus derives from the analy-
sis of its genome sequence (Rosenstein et al.
2009 ). S. carnosus TM300 has a genome size
of 2.56 Mb, similar to that of pathogenic
members of the Staphylococcus genus, such
as S. aureus (2.71 – 2.91 Mb) and S. epidermi-
dis (2.49 – 2.64). Although this species has a
set of conserved genes corresponding to
46% – 50% of the entire chromosome, in
common with S. aureus , S. epidermidis , S.
haemolyticus , and S. saprophyticus , the lack
of known staphylococcal virulence factors in
S. carnosus was confi rmed by genome
sequence. Thus, gene coding for alpha -
hemolysin, gamma - hemolysin, exfoliative
toxins, and superantigens, such as toxic
shock syndrome toxin 1 and enterotoxins,
was not found in S. carnosus TM300 genome.
A complete set of genes involved in meat
adaptation and coding for technological rel-
evant properties is harbored in the genome of
S. carnosus. Genome - based analysis of the
metabolic pathways for energy generation
revealed that this species possesses the
genetic potential for the transport into the cell
and the metabolism of several sugars occur-
ring in meat or added in the batter, such as
glucose, lactose, and ribose. All the enzymes
of the glycolytic pathway, the lactate dehy-
drogenase and the tricarboxilic acid cycle,
and all components of the respiratory chain
are coded by the S. carnosus genome, allow-