RESPONSE OF GROWTH INDICATORS OF THE TWO ALGAE, CHROCCOCCUS TURGIDUS AND CALOTHRIX FUSCA, ISOLATED FROM SPRINGS IN NORTHERN IRAQ TO DIFFERENT LEVELS OF SOME PHYSICAL AND CHEMICAL FACTORS

Abstract

A laboratory study was conducted in the Department of Life Sciences, College of Science, Tikrit University, to evaluate the effect of some physical and chemical factors on two types of algae from the Cyanophycophyta division. The algae were isolated, purified, and identified from freshwater springs in the Sulaimaniyah Governorate. The two types of algae were Chroccoccus turgidus and Calothrix fusca. The algae were activated by repeated subculture on liquid and solid algal media prepared in the laboratory. The study aimed to Evaluate the growth rate (K) and doubling time (G) under the influence of each of the following factors: Growth period (0, 7, 14 days), temperature (20, 24.5, 30 °C), light intensity (400, 1960 Lux), type of culture medium (Chu-10, BG-11), pH (8, 8.5) and Assess the efficiency of the two algae (C. turgidus and C. fusca). Results: The growth rate decreased with increasing experiment time, temperature, light intensity, and pH. The growth rate was 0.313 K on the 14th day of the experiment. The growth rate was 0.308 K at 30 °C. The growth rate was 0.385 K at 1960 Lux. Doubling time increased by 37.74% with increasing experiment time. The high temperature (30 °C) increased the doubling time by 38.93%. Increasing the light intensity to 1960 Lux resulted in the lowest average doubling time with a decrease of 2.24%. The BG-11 medium contributed to a decrease in the growth rate and an increase in the doubling time by 3.29% and 4.15%, respectively. The BG-11 medium recorded the lowest growth rate (0.411 K) and the highest doubling time (1.084 K) compared to the Chu-10 medium, which recorded 0.425 K and 1.039 K. The C. fusca species recorded the highest growth rate, achieving an increase of 16.38% compared to the C. turgidus species. The C. turgidus species required more time to double compared to the C. fusca species, with an increase of 2.98%. Increasing the pH from 8 to 8.5 reduced the doubling time by 18.5%.