Gut Microbiota of Sarawak's "Orang Ulu" Indigenous Community in East Malaysia Reveals Vanish Microbes: A Comparison With Urban Communities.

Introduction: Urbanization often correlates with reduced diversity in human gut microbiota, with notable variations observed between the gut microbiota among the Indigenous communities in rural villages and urban citizens residing in modern settings. Although research has been conducted on the gut microbiota of healthy adults in Malaysia, there has been no study characterising the gut microbiota of Sarawak's Indigenous communities to date. This study aims to fill this gap by examining the gut microbiota profile of the Sarawak Indigenous groups (specifically Orang Ulu subethnic groups Kayan and Kenyah), comparing them with semi-urbanized Selangor Indigenous communities from Peninsular Malaysia (represented by Proto Malay subtribe Temuan) and Urban communities from Kuala Lumpur.

Methods: We conducted a cross-sectional study and collected stool samples from 86 Indigenous participants from Sarawak and compared them with published data from 45 Malaysian Indigenous participants from Selangor and 18 Urban citizens living in Kuala Lumpur City. DNA was extracted from the stool samples, and subsequently, the V4 hypervariable region of the 16S rRNA gene was sequenced. The raw sequence data were analyzed using the Quantitative Insights into Microbial Ecology 2 (QIIME2) bioinformatics platform.

Results and discussion: Analysis revealed that the Sarawak Indigenous community exhibited the highest gut microbial diversity, followed by the Peninsular Indigenous and Urban groups. The Prevotella/Bacteroides (P/B) ratio revealed that the Sarawak Indigenous community showed the highest presence of Prevotella at 88.3%, while Kuala Lumpur Urban residents had a predominantly Bacteroides composition at 61%. The Selangor Indigenous community also exhibited a Prevotella-dominant profile at 75.5%. VANISH microbes (Prevotella, Faecalibacterium, and Succinivibrio) were identified as dominant genera in the Sarawak Indigenous gut microbiota, contrasting with the BIoSSUM microbe (Bacteroidaceae) found in the Kuala Lumpur cohort.

Conclusion: This study sheds light on the distinct gut microbiota composition of Sarawak's Indigenous community, which has not been previously explored. It highlights the impact of urbanization on gut microbiota composition during lifestyle transitions.