This study was conducted to determine whether avilamycin, which is used as a growth promoter in broiler chickens, would affect the structure of the bacterial community within the jejunal intestinal tract. Sixty chickens were assigned to 2 groups: a control group and an avilamycin-treated group. The jejunal tissue from 4 chicks randomly sampled on d 1, 3, 7, 21, and 42 from each treatment group were investigated for changes in villus height, total mesophilic bacteria, lactic acid bacteria, and the structure of the microbial community using PCR-denaturant gradient gel electrophoresis. Supplementation with avilamycin had no effect on villus height and total bacterial count in either the mesophile or lactic acid bacteria. Based on PCR-denaturant gradient gel electrophoresis analysis, 3 bacterial groups were identified in both groups of chicks: gram-positive bacteria having low contents of guanine and cytosine, gamma proteobacteria, and actinobacteria. The abundance of Weisella, Enterococcus faecium, and Pediococcus acidophilus found only in the control group indicated that avilamycin did affect their growth and led to low microbial diversity among the low guanine and cytosine group compared with the control group. In contrast, however, avilamycin treatment was associated with higher microbial diversity among the gamma proteobacteria group in respect of the various Pseudomonas species. This finding should increase awareness of the potential effects of antibiotic use and particularly avilamycin in commercial poultry production in tropical areas.

Abstract. Pungsungvorn N, Wisetsing A. 2021. Short Communication: Isolation and screening of polyhydroxylalkanoates producing microorganisms from Thailand. Biodiversitas 22: 4963-4967. Polyhydroxylalkanotes (PHAs) are polyesters produced in nature by numerous microorganisms. They are biodegradable and are used in the production of bioplastics. In this study, one hundred twenty samples from different regions of Thailand were collected and screened for polyhydroxylalkanoates (PHAs) producing microorganisms. The samples were screened on YM agar containing 0.5 µg Nile-red/mL (YM-NR). Only one isolate of yeast (Y1) gave a positive result on PHA accumulation. The yeast isolate (Y1) was identified as Candida tropicalis by API 20C AUX kit and 18S rRNA nucleotide comparison. The yeast isolate Y1 produced 2.62% PHA   when grown in synthetic N-limiting medium using rice straw hydrolysate as carbon source. The selected four bacteria (B1, B2, B3 and B4) were identified by BlastN of 16S rRNA as Enterobacter cloacae, Enterobacter carcerogenus, Escherichia coli and Klebsiella pneumonia, respectively. The selected yeast and bacterial strains gave PHA content of 2.62, 2.76, 5.38, 3.66 and 0.44%, respectively, in synthetic N-limiting medium using rice straw hydrolysate. Hence, these microorganisms could be used in PHA production from biomass in the future.