| 1. |
|
|
| 2. |
|
|
| 3. |
- Fahlgren, Camilla, et al.
(författare)
-
Annual Variations in the Diversity, Viability, and Origin of Airborne Bacteria
- 2010
-
Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 76:9, s. 3015-3025
-
Tidskriftsartikel (refereegranskat)abstract
- The presence of bacteria in aerosols has been known for centuries, but information on their identity and role in dispersing microbial traits is still limited. This study monitored the airborne bacterial community during an annual survey using samples collected from a 25-m tower near the Baltic Sea coast. The number of CFU was estimated using agar plates while the most probable number (MPN) of viable bacteria was estimated using dilution-to-extinction culturing assays (DCAs). The MPN and CFU values produced quantitatively similar results, displaying a pronounced seasonal pattern, with the highest numbers in winter. The most dominant bacteria growing in the DCAs all formed colonies on agar plates, were mostly pigmented (80%), and closely resembled (>97%) previously cultured bacteria based on their 16S rRNA gene sequences. 16S rRNA gene clone libraries were constructed on eight occasions during the survey; these revealed a highly diverse community with a few abundant operational taxonomic units (OTUs) and a long tail of rare OTUs. A majority of the cloned sequences (60%) were also most closely related to previously ""cultured"" bacteria. Thus, both culture-dependent and culture-independent techniques indicated that bacteria able to form colonies on agar plates predominate in the atmosphere. Both the DCAs and clone libraries indicated the dominance of bacteria belonging to the genera Sphingomonas sp. and Pseudomonas sp. on several sampling occasions. Potentially pathogenic strains as well as sequences closely resembling bacteria known to act as ice nuclei were found using both approaches. The origin of the sampled air mass was estimated using backward trajectories, indicating a predominant marine source.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Hagström, Åke, et al.
(författare)
-
Composition and Seasonality of Membrane Transporters in Marine Picoplankton
- 2021
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we examined transporter genes in metagenomic and metatranscriptomic data from a time-series survey in the temperate marine environment of the Baltic Sea. We analyzed the abundance and taxonomic distribution of transporters in the 3 mu m-0.2 mu m size fraction comprising prokaryotes and some picoeukaryotes. The presence of specific transporter traits was shown to be guiding the succession of these microorganisms. A limited number of taxa were associated with the dominant transporter proteins that were identified for the nine key substrate categories for microbial growth. Throughout the year, the microbial taxa at the level of order showed highly similar patterns in terms of transporter traits. The distribution of transporters stayed the same, irrespective of the abundance of each taxon. This would suggest that the distribution pattern of transporters depends on the bacterial groups being dominant at a given time of the year. Also, we find notable numbers of secretion proteins that may allow marine bacteria to infect and kill prey organisms thus releasing nutrients. Finally, we demonstrate that transporter proteins may provide clues to the relative importance of biogeochemical processes, and we suggest that virtual transporter functionalities may become important components in future population dynamics models.
|
|
| 9. |
- Hagström, Åke, et al.
(författare)
-
Isolates as models to study bacterial ecophysiology and biogeochemistry
- 2018
-
Ingår i: Aquatic Microbial Ecology. - : Inter-Research. - 0948-3055 .- 1616-1564. ; 80:1, s. 15-27
-
Tidskriftsartikel (refereegranskat)abstract
- Here, we examine the use of bacterial isolates growing in artificial media or seawater as a means to investigate bacterial activity in the upper ocean. The discovery of a major role of bacteria in the ocean's carbon cycle owes greatly to the development of culture-independent assemblage-level approaches; however, this should not detract from the recognition of model isolates as representing the environmental microbiome. A long-established tool for culturing bacteria, in medicine and general microbiology, has been agar plates. In addition, a great variety of liquid substrates including seawater have been used to successfully identify and cultivate important bacteria such as Pelagibacter ubique. Yet, the discrepancy between microscopic counts and plate counts, the great plate count anomaly, has led to a biased perception of the limited relevance of isolated bacteria. Linking isolates to whole-genome sequencing, phylogenetic analysis and computational modeling will result in culturable model bacteria from different habitats. Our main message is that bacterial ecophysiology, particularly growth rates in seawater, and functionalities inferred through the identity, abundance and expression of specific genes could be mechanistically linked if more work is done to isolate, culture and study bacteria in pure cultures. When we rally behind a strategy aimed at culturing targeted phenotypes, we are not saying that culture independent studies of bacteria in the sea are not informative. We are suggesting that culturebased studies can help integrate the ecological and genomic views.
|
|
| 10. |
|
|
