Fermentation: Microbiology and Biochemistry 193the assessment of such a potential in strains
involved in meat fermentation. In has been
shown that several Lb. alimentarius , Lb. cur-
vatus , Lb. plantarum , and Lb. sakei strains
harbor such genes, making horizontal gene
transfer possible (Gevers et al. 2003 ).
Whole - genome sequencing of bacteria
and, more accurately, of bacteria capable of
serving as starter cultures has provided new
tools in the quest for the suitable starter
culture. Genome analysis of Lb. sakei 23K
revealed a lack of main aroma - production
pathways, as well as genes responsible for
amino acid decarboxylation (Chaillou et al.
2005 ). Similarly, genome analysis of St. car-
nosus TM 300 has revealed that the genetic
background was present for encoding a series
of desired technological properties, such as
branched - chain amino acid aminotransferase
producing fl avor compounds, superoxide
dismutase, and catalase contributing to the
control of lipid oxidation (Barriere et al.
2001 ; Madsen et al. 2002 ). The presence of
the required genes does not necessarily mean
a functional biochemical pathway, but once
the mechanisms that infl uence their transcrip-
tion and translation are understood, it will be
possible to assess the presence of desired
properties, merely by the use of specifi c
probes bypassing classical microbiological
techniques.Nutritional Aspects
Generally, lactic acid fermentation can have
multiple effects on food nutritional value,
either by modifying the level and bioavail-
ability of nutrients or by interacting with the
gut microbiota and even the human immune
system. The nutrients that determine the
nutritional value of meat are the high biologi-
cal value proteins and micronutrients such as
vitamins B1 and B12, niacin equivalents,
zinc, and iron, with the latter being mainly in
the heme form that can be effi ciently absorbed
by humans (Hambraeus 1999 ; Mann 2000 ).
Currently, there is no data available concern-by most lactobacilli), which increases rancid-
ity and discoloration of the fi nal product.
Despite the fact that catalase production is a
constitutive characteristic of coagulase - neg-
ative staphylococci, it is still regarded as a
desirable property for lactic acid bacteria as
well, and therefore its presence and activity
in lactic acid bacteria has been studied
(Abriouel et al. 2004 ; Noonpakdee et al.
2004 ; Ammor et al. 2005 ).
The utilization of bacteriocinogenic
strains, either as starter or as protective
cultures, has drawn special attention. Several
autochthonous meat lactic acid bacteria,
among them Lactococcus lactis (Rodriguez
et al. 1995 ; Noonpakdee et al. 2003 ), Lb.
sakei (Mortvedt et al. 1991 ; Aymerich et al.
2000 ), Pediococcus acidilactici (Cintas
et al. 1995 ; Albano et al. 2007 ), Lb. curvatus
(Mataragas et al. 2003 ; Messens et al. 2003 ),
Enterococcus faecium (Cintas et al. 1997,
1998 ), and Leuconostoc mesenteroides
(Mataragas et al. 2003 ; Drosinos et al. 2006 )
strains have been screened for bacteriocin
production against several food - borne patho-
gens. Bacteriocin production has been in
many cases optimized, and mathematical
models have been created in order to predict
its production under various conditions
(Drosinos et al. 2008 ). Increased attention
has also been given to the production and
concomitant accumulation of biogenic
amines, due to their potential toxic effects on
consumption. The biogenic amine content of
a variety of meat products has been studied
(Ruiz - Capillas and Jimenez - Colmenero
2004 ). In the case of fermented sausages, the
microorganisms present possess a key role in
their formation, and thus absence of amino
acid decarbolyxase activity has become a key
requirement in the selection of a starter
culture (Ammor and Mayo 2007 ). Finally,
the increased concern regarding the transmis-
sion of antibiotic resistance genes, along with
the ability of several food - associated lactic
acid bacteria to survive passage through the
human gastrointestinal tract, inevitably led to