Seasonal Microbiological Dynamics of Two Salt Lakes in South-East Nigeria

Abstract

A Saline lake is a body of water that has salinity greater than 3 g/l (0.3%), while a hypersaline lake is a water body that has the moderate 35 g/l (3.5%) salt of oceans. Hypersaline lakes, could be classified as either thalassohaline (created from of evaporation of seawater which results in sodium chloride as the major salt, and a salinity greater than that of seawater by a factor of 5 - 10, also having a neutral or slightly alkaline pH); or athalassohaline (stems from non-seawater sources with high concentrations of ions such as magnesium and calcium and sundry other ions such as potassium, or sodium in smaller amounts). This work aims at studying the seasonal microbiological dynamics of Uburu and Okposi salt lakes, whose microbiological properties have not been studied till date. A plethora of fungal isolates were recovered from both lakes using various fungal media prepared with the lake water. Isolates were identified using standard microbiological procedures and molecular typing. Halotolerance test was used to classify the isolates according to their abilities to withstand various degrees of salt concentrations. Isolates retrieved in their descending order of salt tolerance include: Aspergillus flavipes (13 mm at 40%), Penicillium citrinum (10 mm at 40%), Aspergillus ochraceus (9 mm at 40%), Aspergillus nomius (15 mm at 35%), Microsphaeropsis arundinis (12 mm at 35%), Aspergillus sydowi (28 mm at 30%), Penicillium janthinellum (26 mm at 30%), Mucor sp. (13 mm at 30%), Aureobasidium sp. (12 mm at 30%), Trichoderma sp. (9 mm at 30%), Alternaria sp. (22 mm at 25%), Aspergillus sp. (18 mm at 25%), Penicillium sp. (20 mm at 20%), Cladosporium sp. (7 mm at 15%). These isolates were classified as borderline extreme halophiles and moderate halophiles, while no slight halophile was isolated.