The operation of wastewater treatment technologies depends on a combination of physical, chemical and biological factors. Microorganisms present in wastewater treatment plants play essential roles in the degradation and removal of organic waste and xenobiotic pollutants. Several microorganisms have been used in complementary treatments to process effluents rich in fats and oils. Microbial lipases have received significant industrial attention because of their stability, broad substrate specificity, high yields, and regular supply, as well as the fact that the microorganisms producing them grow rapidly on inexpensive media. In Colombia, bacterial community studies have focused on populations of cultivable nitrifying, heterotrophic and nitrogen-fixing bacteria present in constructed wetlands. In this study, culture-dependent methods, culture-independent methods (TTGE, RISA) and enzymatic methods were used to estimate bacterial diversity, to monitor temporal and spatial changes in bacterial communities, and to screen microorganisms that presented lipolytic activity. The dominant microorganisms in the Wastewater Treatment Plant (WWTP) examined in this study belonged to the phyla Firmicutes, Proteobacteria and Bacteroidetes. The enzymatic studies performed indicated that five bacterial isolates and three fungal isolates possessed the ability to degrade lipids; additionally, the Serratia, Kosakonia and Mucor genera presented lipase-mediated transesterification activity. The implications of these findings in regard to possible applications are discussed later in this paper. Our results indicate that there is a wide diversity of aerobic Gram-negative bacteria inhabiting the different sections of the WWTP, which could indicate its ecological condition, functioning and general efficiency.

In Colombia, knowledge of the yeast and yeast-like fungi community is limited because most studies have focused on species with clinical importance. Sediments and water represent important habitats for the study of yeast diversity, especially for yeast species with industrial, biotechnological, and bioremediation potential. The main purpose of this study was to identify and compare the diversity of yeast species associated with sediment and water samples from two artificial lakes in Universidad del Valle (Cali-Colombia). Yeast samplings were performed from fifteen sediment samples and ten water samples. Grouping of similar isolates was initially based on colony and cell morphology, which was then complemented by micro/mini satellite primed PCR banding pattern analysis by using GTG5 as single primer. A representative isolate for each group established was chosen for D1/D2 domain sequencing and identification. In general, the following yeast species were identified: Candida albicans, Candida diversa, Candida glabrata, Candida pseudolambica, Cryptococcus podzolicus, Cryptococcus rajasthanensis, Cryptococcus laurentii, Williopsis saturnus, Hanseniaspora thailandica, Hanseniaspora uvarum, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, Torulaspora delbrueckii, Torulaspora pretoriensis, Tricosporon jirovecii, Trichosporon laibachii and Yarrowia lypolitica. Two possible new species were also found, belonging to the Issatchenkia sp. and Bullera sp. genera. In conclusion, the lakes at the Universidad del Valle campus have significant differences in yeast diversity and species composition between them.

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In recent years, air pollution in urban and rural environments has been increasing and is one of the factors of greatest public health concern. PM2.5 particulate matter is one of the main pollutants that deteriorate air quality. This particulate matter can carry bioaerosols as bacteria and fungi. Due to its size or aerodynamic diameter of less than 2.5 μm, it can be inhaled to the pulmonary alveoli, which is strongly associated with a rise in mortality and morbidity in exposed populations. In this research, the presence of bacteria associated with the PM2.5 fraction of particulate matter was evaluated in two urban areas (Urban-C and Urban-NW) and one rural area (Rural-N) from the Aburrá Valley (Antioquia, Colombia South America). In recent years, this region has been presenting high concentrations of PM2.5, exceeding several times the daily permissible limits (50 μg/m3) for this air pollutant. The isolation, characterization and identification of bacteria associated with PM2.5 was performed by culture-dependent techniques, molecular characterization by ribosomal intergenic spacer analysis (RISA) and 16S rDNA sequencing, respectively. The dominant phylogenetic affiliations of the bacteria were grouped into three phyla: Proteobacteria, Actinobacteria and Firmicutes. The phylum Firmicutes dominated in all sampling points with several genera such as Bacillus, Staphylococcus, Paenibacillus, Lysinibacillus, Exiguobacterium and Macrococcus. Some species of these genera have been linked to pathogenicity in plants, animals and humans. Additionally, a greater presence of possible pathogenic microorganisms in urban areas was estimated, probably influenced by the concentration of PM2.5 and environmental conditions. These results provide important information to understand the distribution and ecology of airborne bacteria and demonstrate that the atmosphere in Colombia (Aburrá Valley) harbors bacteria that are clearly an important, but understudied, component of air quality that needs to be better integrated to the public health perspective.