Background: The glutamate dehydrogenase gene (gdh) is one of the most popular and useful genetic markers for the genotypic analysis of Giardia duodenalis (syn. G. lamblia, G. intestinalis), the protozoan that widely causes enteric disease in humans. To determine the distribution of genotypes of G. duodenalis in Thai populations and to investigate the extent of sequence variation at this locus, 42 fecal samples were collected from 3 regions of Thailand i.e., Central, Northern, and Eastern regions. All specimens were analyzed using PCR-based genotyping and recombinant subcloning methods. Results: The results showed that the prevalence of assemblages A and B among these populations was approximately equal, 20 (47.6%) and 22 (52.4%), respectively. Sequence analysis revealed that the nucleotide diversity of assemblage B was significantly greater than that in assemblage A. Among all assemblage B positive specimens, the allelic sequence divergence within isolates was detected. Nine isolates showed mixed alleles, ranged from three to nine distinct alleles per isolate. Statistical analysis demonstrated the occurrence of genetic recombination within subassemblages BIII and BIV was likely. Conclusion: This study supports increasing evidence that G. duodenalis has the potential for genetic exchange.

Boontanom P, Chantarasiri A. 2020. Short Communication: Diversity of culturable epiphytic bacteria isolated from seagrass (Halodule uninervis) in Thailand and their preliminary antibacterial activity. Biodiversitas 21: 2907-2913. Epiphytic bacteria are symbiotic bacteria that live on the surface of seagrasses. This study presents the diversity of culturable epiphytic bacteria associated with the Kuicheai seagrass (H. uninervis) collected from Rayong Province in Eastern Thailand. Nine epiphytic isolates were identified into four phylogenetical genera based on their 16S rRNA nucleotide sequence analyses. They are considered firmicutes in the genera of Planomicrobium, Paenibacillus and Bacillus, and proteobacteria in the genus of Oceanimonas. Three species of epiphytic bacteria preliminarily exhibited antibacterial activity against the human pathogenic Staphylococcus aureus using the perpendicular streak method. The knowledge obtained from this study increases understanding the diversity of seagrass-associated bacteria in Thailand and suggests the utilization of these bacteria for further pharmaceutical applications.