| Title |
Colonial Cyanobacteria, Microcystis Cell Density Variations using Ultrasonic Treatment |
| Authors |
이혜진 ( Hae-jin Lee ) ; 박혜경 ( Hae-kyung Park ) ; 허준 ( Jun Heo ) ; 이현제 ( Hyeon-je Lee ) ; 홍동균 ( Dong-gyun Hong ) |
| DOI |
https://doi.org/10.15681/KSWE.2018.34.2.210 |
| Keywords |
Cell count; Colonial Microcystis; Lugol`s solution; Ultrasonic treatment |
| Abstract |
It is difficult to count colonial cyanobacteria Microcystis cells since the thickness of colonies is constrained by amorphous mucilage, making it impossible to estimate the number of cells. Disaggregation of Microcystis colonies into single cell is needed to improve the accuracy and precision of cell density estimation of naturally collected samples. Uultrasonic treatment method is commonly used owing to the simplicity and immediacy of the procedure. However, amplitude, frequency, and duration of ultrasonic treatment also cause cell loss during the experiment. Optimal ultrasonic treatment has not been standardized yet. Therefore, the objective of this study was to investigate optimal ultrasonic treatment by analyzing cell density and colony numbers. We collected colonial Microcystis from Changnyeong-Haman weir area in Nakdong River during harmful algal boom period from September to October in 2017. Ultrasonic treatment method was applied to disrupt colonies into single cells to enumerate cell density. Among treatment conditions, results from continuously treated for 100 seconds were found to be the optimum to reduce colonies to a suspension of single cell without cell losses under high and low density of Microcystis cells. Lugol iodine fixed cells followed by sonication showed less negative impact of cell damage within the optimal treatment time (100 seconds). Furthermore, disaggregated cells treated by sonication enables microscopic observation more easily since gas vacuoles were collapsed to facilitate sedimentation of cells under the counting chamber for quantitative enumeration of buoyant Microcystis cells. |