%0 Journal Article
%T 16S rRNA PCR-Denaturing Gradient Gel Electrophoresis of Oral Lactobacillus casei Group and Their Phenotypic Appearances
%A S. Piwat
%A R. Teanpaisan
%J ISRN Microbiology
%D 2013
%R 10.1155/2013/342082
%X This study aimed to develop a 16S rRNA PCR-denaturing gradient gel electrophoresis (DGGE) to identify the species level of Lactobacillus casei group and to investigate their characteristics of acid production and inhibitory effect. PCR-DGGE has been developed based on the 16S rRNA gene, and a set of HDA-1-GC and HDA-2, designed at V2-V3 region, and another set of CARP-1-GC and CARP-2, designed at V1 region, have been used. The bacterial strains included L. casei ATCC 393, L. paracasei CCUG 32212, L. rhamnosus ATCC 7469, L. zeae CCUG 35515, and 46 clinical strains of L. casei/paracasei/rhamnosus. Inhibitory effect against Streptococcus mutans and acid production were examined. Results revealed that each type species strain and identified clinical isolate showed its own unique DGGE pattern using CARP1-GC and CARP2 primers. HDA1-GC and HDA2 primers could distinguish the strains of L. paracasei from L. casei. It was found that inhibitory effect of L. paracasei was stronger than L. casei and L. rhamnosus. The acid production of L. paracasei was lower than L. casei and L. rhamnosus. In conclusion, the technique has been proven to be able to differentiate between closely related species in L. casei group and thus provide reliable information of their phenotypic appearances. 1. Introduction Lactobacillus strains are extensively used as probiotics in the food industry, and certain Lactobacillus species are also of importance in general health, providing a beneficial microflora in the oral cavity [1], intestinal tract [2, 3], and vagina [4]. The genus Lactobacillus contains a diverse assemble of Gram-positive, catalase negative, and nonsporulating, rod-shaped organisms and includes more than 140 species [5, 6]. Among those, Lactobacillus casei group, especially L. casei, L. paracasei, and L. rhamnosus, has attracted a lot of attention over the last 20 years. This is linked to the considerable economic importance of the L. (para)casei species, which is used in many food and feed applications such as dairy products and has a proven record in human and animal health. However, the taxonomy among the species in Lactobacillus casei group is still vague. The uncertain identification leads to confusion in phenotypic characters. In recent years, the identification of lactobacilli evolving along with molecular methods based upon the 16S rRNA gene has been widely used. However, it is still difficult to differentiate unambiguously among these species. Many attempts to discriminate these species yielded inaccurate results, and only limited success could be achieved, largely
%U http://www.hindawi.com/journals/isrn.microbiology/2013/342082/