Establishment of Lactobacillus plantarum strain in honey bee digestive tract monitored using gfp fluorescence.

Lactic acid bacteria are symbiotic bacteria that naturally reside in the gastrointestinal tract of honey bees. They serve a multitude of functions and are considered beneficial and completely harmless. In our experiments Lactobacillus plantarum strain B35, isolated from honey bee digestive tract, was modified using pAD43-25 plasmid carrying a functional GFP gene sequence (gfpmut3a) and used as a model for monitoring and optimisation of the mode of application. The establishment of this strain in honey bee digestive tract was monitored using GFP fluorescence. Three different modes of oral application of this strain were tested: water suspension of lyophilised bacteria, aerosol application of these bacteria and consumption of sugar honey paste containing the lyophilised lactobacilli. Two days after administration the L. plantarum B35-gfp was present throughout the honey bee digestive tract with 104-105 cfu/bee with highest count observed for aerosol application.

Mosaic structure of the small cryptic plasmid pKST23 from Escherichia coli.

Small plasmid pKST23 was isolated from sheep ruminal Escherichia coli population. Plasmid sequence was determined to be 2,779 bp in length and was found to have an overall 42 % of GC pairs. However, its sequence can be divided into two regions based on genetic composition and the GC content. It was found that the high GC region spanning approximately from nucleotide 1,300 to 2,750 was identical to a group of small Escherichia coli plasmids and encoded a putative replication protein identical to plasmid pKL1 Rep protein. The part with lower GC pairs seemed to be more specific as it showed no similarity to the GenBank database. Computational analysis revealed four open reading frames, two of which showed considerable homology to replication proteins. PCR primers targeting parts of the two different regions of plasmid pKST23 were used to assess the occurrence of related plasmids within ruminal E. coli population.

Lactate dehydrogenase gene variability among predominant lactate utilizing ruminal bacteria.

The inter- and intraspecies variability of lactate dehydrogenase (ldh) gene was determined among the predominant ruminal lactate utilizing bacteria. Nearly complete nucleotide sequences of ldh gene, encoding NAD-dependent lactate dehydrogenase of three Megasphaera elsdenii and six Selenomonas ruminantium strains, were obtained and compared. Phylogenetic analyses revealed a limited variability between the ldh sequences studied. The majority of differences observed were silent mutations at the 3rd position of codons. Surprisingly, the intraspecies diversity of the ldh gene among S. ruminantium isolates was higher than the interspecies level between S. ruminantium and M. elsdenii, which strongly suggests the possibility of acquisition of this gene by horizontal gene transfer.