The main goal of this preliminary study was to quantify airborne particles and characterize the dominant cultivable bacterial species as well as some Gram-positive species, and their antibiotic resistance pattern, from environmental samples taken inside and outside of a dairy milking parlour. Sampling was performed over 2 days, in different seasons. The small viable particulate matter < 10 μm (bioaerosols) and cultivable bacteria reached their highest concentrations in the milking parlour. The majority of airborne bacteria in the milking parlour belonged to the genera Staphylococcus (41.9%) and Bacillus (20.9%). A total of 32 different bacterial species of Staphylococcus, Aerococcus, Bacillus, Pseudomonas, Serratia and Acinetobacter were identified. Many of these bacteria may be opportunistic pathogens, causing disease in humans or animals. We found low levels of acquired resistance to the antibiotics commonly used in human or animal infections caused by these opportunistic bacteria. More specifically, resistance to tetracyclines (13.4%), penicillin G (13.4%) and macrolides (7.5%) was identified in Staphylococcus sp. as was a methicillin-resistant S. hominis and resistance to spiramycin (n = 1), lincomycin (n = 1) and streptomycin (n = 2) in Aerococcus sp. An assessment of the occupational risk run by dairy farmers for contracting infections after long- or short-term exposure to micro-organisms requires further studies on the concentration of opportunistic pathogenic bacteria in dairy farm environments.

Microbial community composition and metabolic potential have been explored in petroleum-hydrocarbon-contaminated sludge of an oil storage facility. Culture-independent clone library-based 16S rRNA gene analyses revealed that the bacterial community within the sludge was dominated by the members of β-Proteobacteria (35 %), followed by Firmicutes (13 %), δ-Proteobacteria (11 %), Bacteroidetes (10 %), Acidobacteria (6 %), α-Proteobacteria (3 %), Lentisphaerae (2 %), Spirochaetes (2 %), and unclassified bacteria (5 %), whereas the archaeal community was composed of Thermoprotei (54 %), Methanocellales (33 %), Methanosarcinales/Methanosaeta (8 %) and Methanoculleus (1 %) members. Methyl coenzyme M reductase A (mcrA) gene (a functional biomarker) analyses also revealed predominance of hydrogenotrophic, methanogenic Archaea (Methanocellales, Methanobacteriales and Methanoculleus members) over acetoclastic methanogens (Methanosarcinales members). In order to explore the cultivable bacterial population, a total of 28 resident strains were identified and characterized in terms of their physiological and metabolic capabilities. Most of these could be taxonomically affiliated to the members of the genera Bacillus, Paenibacillus, Micrococcus, Brachybacterium, Aerococcus, and Zimmermannella, while two strains were identified as Pseudomonas and Pseudoxanthomonas. Metabolic profiling exhibited that majority of these isolates were capable of growing in presence of a variety of petroleum hydrocarbons as sole source of carbon, tolerating different heavy metals at higher concentrations (≥1 mM) and producing biosurfactant during growth. Many strains could grow under a wide range of pH, temperature, or salinity as well as under anaerobic conditions in the presence of different electron acceptors and donors in the growth medium. Correlation between the isolates and their metabolic properties was estimated by the unweighted pair group method with arithmetic mean (UPGMA) analysis. Overall observation indicated the presence of diverse groups of microorganisms including hydrocarbonoclastic, nitrate reducing, sulphate reducing, fermentative, syntrophic, methanogenic and methane-oxidizing bacteria and Archaea within the sludge community, which can be exploited for in situ bioremediation of the oily sludge.