How Culture Medium pH Range Influence Phytoplankton Growth Performance and Biochemical Content

Abstract

Thalassiosira are commonly used algae in mass production (Muller-Feuga, 2000). Certain species from different phytoplankton classes could overcome stress in natural environment, as they can exceed other microalgae classes, sometimes they vigorously grow and forming bloom generating secondary metabolites in the surrounding aquatic environment (Taheri et al., 2017). Influence of pH factor on the metabolic activity, biochemical constituents and ultrastructure of various algae was tested by (Sharma et al., 2012, Safafar et al., 2016. Also light intensity, temperature and minerals affect growth of cyanobacteria detected by (Katoli et al., 2015). There is a relation between phytoplankton uptake of inorganic carbon during photosynthesis process and increase pH of the surrounding environment (Hansen, 2002). However, in the algal culture medium pH is considered one of the most important factors influence optimal algal growth, it controls algal metabolism and affects its bioactive products biosynthesis (Liu and Lee, 2000). Chlorella spp. and Scenedesmus spp. are green phytoplankton commonly incorporated in food industries because of its high protein and lipid content, (Barka and Blecker, 2016). Nannochloropsis spp. of phytoplankton belongs to Eustigmatophyceae. Although its first record was in marine water (Vareltzis and Undeland, 2012) it commonly recorded in both fresh and marine environment. This species gained its importance from its high biochemical constituents and its possible mass production. A laboratory study about Chlorella spp. use as safe protein source for consumption and dietary supplementation and as natural food for some zooplankton species was tested by (Hegab et al., 2019) and concluded that Chlorella vulgaris is used as food source for Brachionus plicatilis and Heterocypris salina. Zooplankton species grazing and ingestion rates were mainly depending on Chlorella densities. Chlorella vulgaris, Scenedesmus quadricauda and Nannochloropsis oculata are known to be used in biodiesel production (Metsoviti et al., 2019) and as feed for fish (Pulz and Gross, 2004). Optimization of the conditions of algal cultivation may lead to production of algal biomass in adequate microalgae quantity (Vasileva et al., 2015).The major scope is using of algae as feed to higher planktons and other organisms in the food web. Microalgae proteins are one of the most important sources of protein to fill the gap in usual protein sources (Barka and Blecker, 2016). Micro algal protein content of Spirulina paltensis constitutes (50-65%) compared to fish protein (24%), (Moorhead et al., 2011). Chlorella vulgaris protein constitutes (43-58% of its dry weight) differs by culture conditions (Safi et al., 2014). Algal usage in different industries in cosmetics, food products enlarge the need for mass production of algae, so there is a growing interest for focus studies on the algal optimum condition needed for optimum growth. So, this study investigate the growth response and total biochemical content of three species of phytoplankton cultu...

Production of Antioxidants and High Value Biomass from Nannochloropsis oculata: Effects of pH, Temperature and Light Period in Batch Photobioreactors

“…Chosen sets of conditions were: (A) 35 C, pH 9.5, 24:0 LP. The ranges of pH and temperature were chosen according to the literature, since Nannochloropsis has been reported to grow at pH 6-9.5 or higher [36,39], and temperatures as low as 17 • C and as high as 40 • C [18,31]. Even though extreme pH and temperature were expected to not be optimal for growth, their effects on the biomass composition would be valuable in the development of a two-stage cultivation process, in which biomass is initially grown optimally and subsequently exposed to stress in order to accumulate the desired product.…”

Effect of KW21 and water-extracted horseradish leaf combination on Nannochloropsis sp. density in laboratory scale

“…A pH of 7-8 is the optimum pH range for the growth of Nannochloropsis sp. cells (Sahira et al, 2017), and the best growth occurs at a pH of 9 (Zaher & Helal, 2020).…”