Occurrence and Density of Alkalophilic Bacteria and Fungi in Saline Soils of Makkah District, Saudi Arabia PDF

Keywords

soil samples, bacteria, fungi

Abstract

All soil samples were inhabited by alkalophilic, including alkalotolerant, bacteria in counts ranging from 3.7 to 37.2 (x 10^4)/g oven-dried soil. The density of alkalophilic fungi was significantly lower and their occurrence was restricted to only three sites out of four. The total alkalophilic bacteria of samples in vicinity of sea water were higher than in other inland samples. In presence of low organic matter, salinity appeared of more drastic effect on alkalophilic fungal population than bacteria. Increased content of soil organic matter appeared as a factor, beside others, which plays a probably role in minimizing the inhibitory effect of high salinity. The genus Bacillus predominated in frequency, Gram negative rods were of moderate occurrence, while Gram positive micrococci and Gram positive asporogenous rods were of low frequency. Only 3.4 to 33.3% of Bacillus isolates together with all Gram positive asporogenous rods were obligate alkaliphiles; the remaining isolates were either facultative or alkaline-tolerant. Eight fungal genera could be identified as alkalophilic fungi. Aspergillus was the highest in occurrence but Fusarium was the highest in density at only one site.