Genetic Diversity and Molecular Phylogeny of Cyanobacteria from Sri Lanka Based on 16S rRNA Gene

Abstract

The diversity of cyanobacteria in Sri Lanka was studied in different water reservoirs, paddy fields, brackish water and tsunami affected areas using light microcopy, 16S rRNA sequences, followed by phylogenetic analysis. Based on light microscopy, 24 genera were identified from environmental samples belonging to the orders Chroococcales, Oscillatoriales, Pleurocapsales and Nostocales. In cultures, 33 genera were identified from all five cyanobacterial orders, including Stigonematales. Based on 16S rRNA gene sequences and their morphology, two isolates were identified up to species level, 72 to genus level, one isolate up to family and 11 up to order level. Twelve isolates couldn't be assigned to any taxonomic level. The results of 16S rRNA gene sequences along with the phylogenetic analysis indicated that some cyanobacterial isolates could be accommodated to genus or order level. The 16S rRNA sequence analysis data in this study confirmed that order Nostocales and order Pleurocapsales cyanobacteria are monophyletic while orders Chroococcales, Oscillatoriales and Stigonematales cyanobacteria are polyphyletic. Polyphasic approach including the combination of light microscopy, cultures and the analysis of 16S rRNA gene sequences provide a promising approach to ascertain the diversity of cyanobacteria in different habitats.

Co-occurrence of microcystin and cylindrospermopsin in hypereutrophic Mahakanadarawa and Nachchaduwa reservoirs

“…According to our observations, the spatial distribution pattern of CYN in Mahakanadarawa reservoir is approximately uniform while in Nachchaduwa it showed slight accumulation toward the direction of the South (Figures 4b and 4d). Although we did not observe any of the CYN-producing cyanobacterial species in either of the reservoirs, Wanigatunge et al (2014) and Yatigammana and Perera (2017) have reported the presence of potential CYN-producing cyanobacterial species Cylindrospermopsis raciborskii in Nachchaduwa. However, in this study, we did not observe C. raciborskii or any other CYNproducing species probably due to two reasons, one is the presence of very low densities of such filaments at the time of sampling due to their disappearance.…”

“…At the same time, Mycrocystis was identified as a dominant genus in northern dry zone reservoirs (Jayawardana et al 1998). Several later research reported toxigenic genera Cylindrospermopsis raciborskii as the dominant cyanobacterial community in several northern dry zone reservoirs and its co-occurrence with Microcystis only in Unnichchai tank (Wanigatunge et al 2014;Kulasooriya 2017 andYatigammana andPerera 2017). Further, several other toxin-producing cyanobacteria such as Planktolyngbya, Pseudoanabaena, Anabaena aphanizomenoides (Silva and Wijeyaratne 1999), Phormidium, Oscillatoria (Liyanage et al 2014) and Lyngbya (Shihana et.…”

First record of cyanobacteria species: Cephalothrix komarekiana, from tropical Asia

“…Favorable environmental conditions such as sufficient amounts of sunlight, water temperature, pH and nutrient rich environment could cause higher diversity of cyanobacteria in Dry zone. Though 45 genera are reported so far from this tropical region, Sri Lanka [36], a recent study carried out by Wanigatunge et al [6] reported 26 genera out of them. Another study reports about 40 species of cyanobacteria belonging to 24 genera from Sri Lankan reservoirs [37].…”

“…Among them, the studies applying a polyphasic approach are even more limited. The cyanobacteria diversity in different water reservoirs, paddy fields, brackish water and tsunami affected areas in Sri Lanka has been studied using a polyphasic approach including the combination of light microscopy, cultures and the analysis of 16S rRNA gene sequences by Wanigatunge et al [6]. Sethunge and Manage [4] have identified toxin producing, filter clogging, taste and odor forming nuisance algae and some physio-chemical parameters in some selected water bodies in Sri Lanka.…”

Investigation of the value-added potential of some selected freshwater cyanobacteria

“…Higher photosynthetic ability, simple, rapid and ubiquitous growth, equal or better nutritional quality compared to some traditional crops, the ability to utilize the same space for regrowth and continuous production of quality harvest throughout the year with less capital investment and zero environmental pollution, make cyanobacteria more promising and sustainable to be used in food and cosmetics industry to ensure good health status in global population. Diversity of cyanobacteria in tropics is remarkably high and tropical islands such as Sri Lanka provide habitats for a diverse collection of cyanobacteria (Hossain et al, 2020;Senanayake and Yatigammana, 2017;Wanigatunge et al, 2014) with an unexplored industrial potential, specifically in food and cosmetic industries. Therefore, the major objective of the study was to evaluate the value-added potential of some selected Sri Lankan freshwater cyanobacteria in providing sustainable solutions for malnutrition and UV induced skin damage.…”