toxins Article Microcystis Sp. Co-Producing Microcystin and Saxitoxin from Songkhla Lake Basin, Thailand Ampapan Naknaen 1, Waraporn Ratsameepakai 2, Oramas Suttinun 1,3, Yaowapa Sukpondma 4, Eakalak Khan 5 and Rattanaruji Pomwised 6,* 1 Environmental Assessment and Technology for Hazardous Waste Management Research Center, Faculty of Environmental Management, Prince of Songkla University, Hat Yai 90110, Thailand;
[email protected] (A.N.);
[email protected] (O.S.) 2 Office of Scientific Instrument and Testing, Prince of Songkla University, Hat Yai 90110, Thailand;
[email protected] 3 Center of Excellence on Hazardous Substance Management (HSM), Bangkok 10330, Thailand 4 Division of Physical Science, Faculty of Science, Prince of Songkla University, Hat Yai 90110, Thailand;
[email protected] 5 Department of Civil and Environmental Engineering and Construction, University of Nevada, Las Vegas, NV 89154-4015, USA;
[email protected] 6 Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai 90110, Thailand * Correspondence:
[email protected]; Tel.: +66-74-288-325 Abstract: The Songkhla Lake Basin (SLB) located in Southern Thailand, has been increasingly polluted by urban and industrial wastewater, while the lake water has been intensively used. Here, we aimed to investigate cyanobacteria and cyanotoxins in the SLB. Ten cyanobacteria isolates were identified as Microcystis genus based on16S rDNA analysis. All isolates harbored microcystin genes, while five of them carried saxitoxin genes. On day 15 of culturing, the specific growth rate and Chl-a content were 0.2–0.3 per day and 4 µg/mL. The total extracellular polymeric substances (EPS) content was Citation: Naknaen, A.; 0.37–0.49 µg/mL.