Epipelic cyanobacterial diversity in Pinang River basin, Malaysia, revealed by 16S-based metagenomic approach

Abstract

Cyanobacteria are the most widespread group of photosynthetic prokaryotes. They are primary producers in a wide variety of habitats and are able to thrive in harsh environments, including polluted waters; therefore, this study was conducted to explore the cyanobacterial populations inhabiting river tributaries with different levels of pollution. Sediment samples (epipelon) were collected from selected tributaries of the Pinang River basin. Air Terjun (T1) and Air Itam rivers (T2) represent the upper streams of Pinang River basin, while Dondang (T3) and Jelutong rivers (T4) are located at in the middle of the river basin. The Pinang River (T5) is located near the estuary and is subjected to saline water intrusion during high tides. Cyanobacterial community was determined by identifying the taxa via 16S rRNA gene amplicon sequence data. 16S rRNA gene amplicons generated from collected samples were sequenced using illumina Miseq, with the targeted V3 and V4 regions yielding approximately 1 mln reads per sample. Synechococcus, Phormidium, Arthronema and Leptolyngbya were found in all samples. Shannon-Weiner diversity index was highest (H’ = 1.867) at the clean upstream station (T1), while the moderately polluted stream (T3) recorded the lowest diversity (H’ = 0.399), and relatively polluted stations (T4 and T5) recorded fairly high values of H’. This study provides insights into the cyanobacterial community structure in Pinang River basin via cultivation-independent techniques using 16S rRNA gene amplicon sequence. Occurrence of some morphospecies at specific locations showed that the cyanobacterial communities are quite distinct and have specific ecological demands. Some species which were ubiquitous might be able to tolerate varied environmental conditions.