Isolated cases of lactobacillemia have been reported in at-risk populations, but lactobacilli present an essentially negligible biological risk.
The entire genomes of several lactobacilli have been sequenced ( Klaenhammer, 2002a ): e.g. Man and microorganisms are engaged in constant competition for food supplies ( Steinkraus, 2002 ).
The Earth is thought to be about 4.5 billion years old, and microorganisms were the first life-forms to appear.
These sweeping changes cause confusion and some previous identifications of lactobacilli may yet be subject to change.
The use of molecular methods has revolutionized identification, improving its quality and efficacy.
Bacteria of the genus are beneficial microorganisms of particular interest because of their long history of use ( Holzapfel, 2002 ).
Lactobacilli were among the first organisms used by man for processing foodstuffs ( Konigs, 2000 ) and for preserving food by inhibiting invasion by other microorganisms that cause foodborne illness or food spoilage ( Adams, 1999 ).
Grown on glucose as a carbon source, lactobacilli may be homofermentative (producing more than 85% lactic acid) or heterofermentative (producing lactic acid, carbon dioxide, ethanol, and/or acetic acid in equimolar amounts).
The genus ( Kandler & Weiss, 1986 ), taking account of the increased number of known species, reorganizes the nomenclature into three groups: I (obligate homofermentative), II (facultative heterofermentative) and III (obligate heterofermentative).
Since then, the beneficial effects of probiotic fermented products, many of which contain lactobacilli, have been studied extensively.
The number of articles published on lactobacilli has steadily increased over the past 15 years, reaching 666 publications in 2004, 26% of which included [(lactobacilli or GG, isolated from the healthy human intestinal flora ( Goldin, 1992 ).
The techniques used for polyphasic analysis of lactobacilli have been reviewed elsewhere ( Coeuret, 2003 ).