BackgroundThe 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.ResultsThe 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.ConclusionThis study supports increasing evidence that G. duodenalis has the potential for genetic exchange.

Abstract. 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.

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This study proposed the isolation, screening and identification of cellulase-producing bacteria from Thai coastal wetland soil. Eighty seven bacterial strains which demonstrated cellulase-producing bacteria were investigated for cellulolytic properties. The bacterium identified as Bacillus cereus strain BR0302 exhibited the highest hydrolysis activity on carboxymethylcellulose agar plates. Cellulolytic performance for CMCase activity and FPase activity was 0.121 ± 0.006 and 0.057 ± 0.001 U/mL respectively. Cellulolytic characteristics showed that the B. cereus strain BR0302 could be used for the hydrolysis of cellulosic biomass for biofuel production.

Durian (Durio zibethinus) is known as the king of fruit in Southeast Asia (Bampenrat et al., 2020), and is one of the most economically important export fruits in Thailand (Charoensumran et al., 2021). However, a major problem affecting durian plantations in Thailand is stem rot disease. Symptoms of the infected trees are bark and trunk canker, twig blight, yellow leaves, and wilting.