The Genera Lactobacillus and Carnobacterium
- PDF / 1,488,229 Bytes
- 84 Pages / 539 x 751 pts Page_size
- 88 Downloads / 289 Views
CHAPTER 1.2.10 ehT
areneG
su l l i cabot caL
dna
mu i re t cabonraC
The Genera Lactobacillus and Carnobacterium WALTER P. HAMMES AND CHRISTIAN HERTEL
Lactobacilli are Gram-positive, nonsporeforming rods, catalase-negative when growing without a heme source (e.g., blood), usually nonmotile, and occasionally nitrate reducers. They utilize glucose fermentatively (Kandler and Weiss, 1986a) and may be either homofermentative, producing more than 85% lactic acid from glucose, or heterofermentative, producing lactic acid, CO2, ethanol, and/or acetic acid in equimolar amounts. The type species is Lactobacillus delbrueckii Leichmann 1896 (Beijerinck, 1901). The genus Lactobacillus constitutes together with the genus Pediococcus the family Lactobacillaceae and presently comprises 80 recognized species and 15 subspecies. The phylogenetic position of this family in relation to lactic acid bacteria (LAB) and closely related genera is depicted in Fig. 1. The increased interest in microbial ecology and the availability of sensitive taxonomic methods delivering unambiguous identification results have created a marked increase in the number of species within the genera Lactobacillus and Carnobacterium since the previous edition of The Prokaryotes. The validly described species of the genus Lactobacillus are listed in Table 1, and those of the genus Carnobacterium are treated under a separate headline. Lactobacillus rogosae is not included in Table 1 as no type strain with the original description is available in culture collections (Kandler and Weiss, 1986a). In addition, L. catenaformis and L. vitulinus have not been included because 16S rRNA sequence analyses show that these species are closely related to Clostridium ramosum, C. spiroforme, C. cocleatum and the genus Coprobacillus. In Table 1, the numbers in column I indicate species for which 16S rRNA sequence data of 90% of the bases are available. These have been used to construct phylogenetic trees shown in Figs. 2–9. The species attribution to phylogenetic groups (shown in Figs. 3–9) as well as to groups of main habitats is included in Table 1. On the basis of the results of genotypic studies, the genus Lactobacillus comprises a defined group of organisms, which consists of subgroups (Table 1, column V) that are sufficiently genotypically dis-
tinct as to justify their attribution to several genera. The recent creation of the genus Weissella from a homogenous group of heterofermentative LAB (formerly included in the genus Lactobacillus; Collins et al., 1993) is a consequent step in that direction, and the description of Paralactobacillus follows this development. On the other hand, the morphological, biochemical and physiological characteristics of the lactobacilli are usually not so diverse that they demand a separation into different genera. The genus Carnobacterium had also been included in the genus Lactobacillus (Collins et al., 1987). It presently contains 7 validly described species, with Carnobacterium divergens being the type species. These organisms share some ha
Data Loading...
