Abstract

We investigated the influence of microwave radiation on physiological behaviors ofPhormidium sp. Kützing ISC31 (Oscillatoriales). The organism grown in BG-11 medium was microwave-treated at a frequency of 2450 MHz using a microwave oven. Fifteen (15) microwave pretreatments were established, combining five intensities (180, 360, 540, 720 and 900 W/cm²) and three periods of pretreatment [10, 20 and 30 second(s)]. Our results revealed that samples exposed to microwave various intensities showed significantly higher growth rates and biomass than that of non-irradiated controls. The content of chlorophyll a, which exists in the thylakoid membrane, decreased with increase in field strength and duration of exposure. Synthesis of the phycobiliproteins (PBP), phycocyanin (PC), phycoerythrin (PE) and allophycocyanin (APC), except in 720 and 900 W/cm² (30 s), increased in all exposures as compared to that of control. Photosynthetic activity rate compared to nitrogenase activity increased in all microwave exposures except in 180 W (10 s) and 720 W (10 s). Identification was carried out by molecular method. The result of PCR blasted with sequenced cyanobacteria in NCBI showed 97% homology to the 16S rRNA ofPhormidium sp. This study revealed that various microwave intensities induce different physiological effects, depending on field strength and duration of exposure.

Key words: 16S rRNA gene, PCR, Phormidium, microwave treatment, physiological characteristic, paddy field