Temporal Variation and Phylogeny of Air and Surface Microflora in Relation to Occupancy Patterns in a Higher Education Institution (HEI)

Abstract

People not only inhale life-sustaining oxygen but also traces of bacteria and even inanimate surfaces introduce microorganisms to one’s bodies. However, the diversity and richness of bacterial communities both indoor and outdoor in a Philippine HEI in relation to human occupancy patterns remain relatively unexplored. Hence, the study aimed to bridge this gap. Microflora were collected using settle plates and swabbing method and identified by comparing their 16s rRNA gene amplicons using the Basic Local Alignment Tool. Several isolates were found to have biological implications in health (e.g. Staphylococcus haemolyticus and Bacillus clarus) and biotechnology (e.g. Rhodococcus pyridinivorans and Bacillus altitudinis). The phylogeny of samples exhibited close cohesion from the genus level, hence forming monophyletic taxa – under the classes Bacilli, Gammaproteobacteria, and Actinomycetes. Furthermore, statistical results established the significant relationship between indoor air and outdoor surface microbial load with the volume of occupants, as opposed to outdoor air and indoor surfaces. The analysis also revealed a strong correlation between the volume of occupants and indoor air microbial concentration (p = 0.002, R = 0.998), likewise in the case of indoor and outdoor surface bacterial contamination (p = 0.036, R = 0.664). Additionally, there was a significant difference in the indoor and outdoor air microbial load following human occupancy patterns in the area (p = 0.018). Findings of the study provide a foundation for understanding air and surface-borne flora, as well as a basis for the enhancement of health and safety standards for building inhabitants.