Black Soot: Percentage Source and Aeromicrobiology

Black soot in aerosols of Niger Delta, Nigeria especially Port Harcourt is attracting global concern. Six major sources of black soot have been identified; Burning of local “kpo-fire” crude oil for production of diesel and Kerosene 67.5%, Smoke from refinery and petro-chemical industries 20%, Gas flaring from flow station of oil companies 5%, Smoke from generators both industrial and domestic 3%, Smoke from exhaust of vehicles of all types 1.5%, Burning of vehicle tyres either at animal slaughter abbatoir or for other purposes 3%. This present research aimed at analyzing and comparing the variations of aero-microbiological status of Black soot in campus lecture halls located in different altitudes (Ground, first and second floor) of 36feet height; 10feet each floor. The study area was lecture halls in Rivers State University in three departments namely: Microbiology (MCR), Lecture halls I IV, ground floor; Animal and Environmental Biology (AEB), Lecture halls I – IV, first floor and Plant Science and Biotechnology (PSB), Lecture halls I – IV, second floor. It was conducted in the month of June, 2017; Monitored in all the lecture halls morning 7:00am and afternoon 12:00pm on 7, 10 and 13 June, 2017 . Standard microbiological techniques were used; Bacteria and fungi load of air of the selected departments were determined using Settle Plate Technique (Sedimentation method). In this technique, air microbes settled directly on the prepared agar plates (Nutrient Agar NA, MacConkey Agar MCA, Sabouraud Dextrose Agar SDA) exposed for a period of 10 minutes. Samples were collected twice daily at 7:00 am, and 12:00 pm in each class room in the various departments. After exposure, the samples were taken to the laboratory and incubated at 37C for 24 hrs for NA, 42C for 24hrs for MCA and SDA plates were incubated at 25C (room temperature) for 4 days. Once colony forming units (CFU) were enumerated, CFU/10mins were determined. Identification of isolates was done using standard methods. Microbial Percentage (%) frequency associated with black soot at different altitude Ground floor (GF), First floor (FF) and Second floor (SF) were; Total Heterotrophic Bacteria: FF (38.7) > GF (34.1) > SF (27.1); Enteric Bacteria: GF (44.9) > FF (27.9) > SF (27.2); Total Fungi: GF (38.8) > FF (36.6) > SF (27.5) (Fig. 1). The overall percentage (%) microbial load revealed that Ground floor sampled at a height of 2m form the ground has the highest load 39% (117.8), followed by First floor 34% (110.3) while Second floor had the least 27% (81.8) The colonies formed during the afternoon sampling were higher the ones for morning sampling. This was due to the atmospheric condition in relation to increased wind/air flow; increased activities from sources of black soot in afternoon more than morning hours. The percentage (%) frequency of bacteria genera isolated were Bacillus sp (39.0%) > Staphylococcus sp (21.2%) > Pseudomonas sp (14.9%) > Streptococcus sp (14.4%) > Klebsiella sp (6.0%) > Micrococcus sp (4.5%) while fungal isolates were Candida sp (34.9%) > Penicillium sp (21.4%) > Mucor sp (21.4%) > Aspergillus niger (11.3%) Aspergillus flavus (10.4%). The enteric organisms were Klebsiella sp (34.3%) > Escherichia coli (32.2%) > Enterobacter sp (25.5%) > Shigella sp (8%). Conclusively, the occurrence of pathogenic microorganisms (Escherichia coli, Staphylococcus and Bacillus) mixed with black soot is of great health importance. Also, long exposure to black soot could cause cancer.