Abstract
This research was conducted to determine the microbial contamination of the educational environment in Dammam, Saudi Arabia. The estimated percentage of pollution of the ceilings of 12 educational buildings had a ratio of 1.34-72.06%. The samples were obtained from walls, room ceilings, toilets and cafeteria specimens from different educational buildings. The results showed the most common fungal isolates from classroom walls (45.42%), ceiling (32.39%), toilet (17.37%) and cafeteria (4.81%). Relative densities from all specimens are obtained from walls, room ceiling, toilet and cafeteria showed Aspergillus ochraceus (23.49%) followed by Stachybotrys sp. (2904 Aspergillus flavus (19.3%), Rhizoctonia sp. (9.7%) and Aspergillus niger (7%), Penicillium sp. Other fungal isolates including Aspergillus fumigatus. Fusarium sp., Alternaria alternata,Cladosporium sp. and Aspergillus flavipes had less than 5% overall relative density. From all dust samples analyzed from classrooms air conditioning systems, six fungal genera with different numbers of species were recorded: Stachybotrys sp., Rhizoctonia sp., Aspergillus niger Aspergillus flavus, Penicillium spp and Rhizopus stolonifer. Other bacterial isolates included Staphylococcus aureus, Neisseria sicca, Micrococcus yoseus, Pseudotnonas aeruginosa, Staphylococcus epidermidis, Bacillus subtilis and Proteus mirabilis, all isolated from air conditioning. Despite the importance of cooling and air conditioning systems indoor, it contributed significantly to the increase of microbes in the air of those places, where Aspergillus niger; Aspergillus flavus and Stachybotrys sp. were most frequent in isolation and chosen for physiological tests to determine the effect of different temperature and relative humidity. The results showed that the optimum temperature for all three fungi were 25 degrees C, while the relative humidity was 100% best for all tested fungi.