Isolation and Morphological Identification of Two Freshwater Green Microalgae Isolated from Different Aquatic Habitats in Iraq

Abstract

Microalgae that live in freshwater form an important element to wetlands and there has been much interest developed surrounding their ecological significance and their potential use in biotechnological applications and remediation efforts for environmental conditions. We aim, in the current study, to examine the morphological characteristics of the samples taken from multiple aquatic ecosystems across Iraq's freshwater environments. Samples were obtained from a wastewater treatment basin at the Samarra Drug Industries Plant and along with two sample sites along the Tigris River, which receives wastewater effluent, within Baghdad (where discharge occurs). Isolation of the samples was performed using serial dilution and streak plate methods on CH-13 medium maintained under laboratory conditions. Purified cultures of axenic strains were produced that were free of bacterial and/or fungal contamination. Light microscopy and taxonomic keys were used in morphological assessments. Morphologically, the isolates were all different based on the size, shape, and structural characteristics of their cells, cell walls, chloroplasts, and reproduction. The Chlorococcum humicola isolate was characterized as large (spherical or subspherical) with thick walls, dark green pigment, and parietal chloroplasts. Alternatively, the Chlorella vulgaris isolate was described as small and spherical, with bright green pigmentation, cup-shaped chloroplasts, and reproducing via autospore formation. The fact that two species were isolated from contaminated aquatic habitats suggests there is some resilience to environmental stresses and points toward their potential application in wastewater treatment and bioremediation. The data generated here contributes to existing data regarding the microalgal biodiversity indigenous to Iraq, and provides information that can be utilised in future physiological and environmental studies.