Effects of Light Intensity and Exposure Period on the Growth and Stress Responses of Two Cyanobacteria Species: Pseudanabaena galeata and Microcystis aeruginosa

Guligena Muhetaer,Takashi Asaeda,Hongyu Yan,Helayaye D L Abeynayaka,Senavirathna M D H Jayasanka,M Harun Rashid,Mahendra B Baniya

doi:10.3390/w12020407

Guligena Muhetaer, Takashi Asaeda + Show 5 more

Open Access

https://doi.org/10.3390/w12020407

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Abstract

Light is an important factor that affects cyanobacterial growth and changes in light can influence their growth and physiology. However, an information gap exists regarding light-induced oxidative stress and the species-specific behavior of cyanobacteria under various light levels. This study was conducted to evaluate the comparative effects of different light intensities on the growth and stress responses of two cyanobacteria species, Pseudanabaena galeata (strain NIES 512) and Microcystis aeruginosa (strain NIES 111), after periods of two and eight days. The cyanobacterial cultures were grown under the following different light intensities: 0, 10, 30, 50, 100, 300, and 600 μmol m−2 s−1. The optical density (OD730), chlorophyll a (Chl-a) content, protein content, H2O2 content, and the antioxidative enzyme activities of catalase (CAT) and peroxidase (POD) were measured separately in each cyanobacteria species. P. galeata was negatively affected by light intensities lower than 30 μmol m−2 s−1 and higher than 50 μmol m−2 s−1. A range of 30 to 50 μmol m−2 s−1 light was favorable for the growth of P. galeata, whereas M. aeruginosa had a higher tolerance for extreme light conditions. The favorable range for M. aeruginosa was 10 to 100 μmol m−2 s−1.

Highlights

Eutrophication and global warming have promoted the growth of cyanobacteria in freshwater systems worldwide, and this trend is expected to increase in the future [1]
They play imperative roles in carbon and nutrient cycling in aquatic systems, as well as in degrading water quality and safety, causing numerous problems with water sources and ecosystem management [4]. Cyanobacterial blooms and their effects have been reported in the scientific literature for more than a century, and their probability and severity have both escalated over time [5]
Strains of the cyanobacterial species P. galeata and M. aeruginosa were obtained from the National

Summary

Introduction

Eutrophication and global warming have promoted the growth of cyanobacteria in freshwater systems worldwide, and this trend is expected to increase in the future [1]. Cyanobacterial blooms are a serious issue in fresh, brackish, and marine water, as they decrease light penetration through the water and deplete dissolved oxygen, causing mortality for aquatic life [2]. They play imperative roles in carbon and nutrient cycling in aquatic systems, as well as in degrading water quality and safety, causing numerous problems with water sources and ecosystem management [4]. The mass development of cyanobacteria has resulted in various negative consequences including eutrophication, ecosystem imbalances, and scenic impairments [6]. Their ability to produce toxic secondary metabolites is becoming an increasingly important environmental issue, which is threatening human, animal, and plant health. Gaps in our knowledge of cyanobacteria must be filled

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