2. Methods
The algal culture used in this study,G. sulphuraria CCMEE 5587.1, was obtained from Culture Collection of Microorganisms
from Extreme Environments (University of Oregon). Bacteria-free colonies were picked from glucose-containing agar plates to estab-lish axenic stock cultures and cultivated in 16-mm borosilicate glass tubes (culture volume = 6 mL) with a parafilm wrap aroundthe closure to minimize evaporative losses while permitting O2and CO2 diffusion. In all the tests, initial pH level of the media was adjusted to 2.5 by adding 10 N sulfuric acid. The tubes were
placed in a tissue-culture roller drum (New Brunswick Scientific Co., Edison, NJ, USA) housed in a CO2-enriched (2–3% vol/vol) incubator (Percival, USA) and maintained at 40°C in a 14-h/10-hlight–dark cycle mimicking outdoor conditions. Biomass growth was analyzed daily, based on measurements of optical density at 750 nm (OD 750) using Beckman DU-530 UV/Vis spectrophotome-ter and converted to ash-free dry weight (AFDW, g L1) using the correlation established in the previous study (Selvaratnam et al.,2014b)