ALBERT

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gruen, D. S., Wolfe, J. M., & Fournier, G. P.. Paleozoic diversification of terrestrial chitin-degrading bacterial lineages. BMC Evolutionary Biology, 19, (2019): 34, doi:10.1186/s12862-019-1357-8.

Description: Background Establishing the divergence times of groups of organisms is a major goal of evolutionary biology. This is especially challenging for microbial lineages due to the near-absence of preserved physical evidence (diagnostic body fossils or geochemical biomarkers). Horizontal gene transfer (HGT) can serve as a temporal scaffold between microbial groups and other fossil-calibrated clades, potentially improving these estimates. Specifically, HGT to or from organisms with fossil-calibrated age estimates can propagate these constraints to additional groups that lack fossils. While HGT is common between lineages, only a small subset of HGT events are potentially informative for dating microbial groups. Results Constrained by published fossil-calibrated studies of fungal evolution, molecular clock analyses show that multiple clades of Bacteria likely acquired chitinase homologs via HGT during the very late Neoproterozoic into the early Paleozoic. These results also show that, following these HGT events, recipient terrestrial bacterial clades likely diversified ~ 300–500 million years ago, consistent with established timescales of arthropod and plant terrestrialization. Conclusions We conclude that these age estimates are broadly consistent with the dispersal of chitinase genes throughout the microbial world in direct response to the evolution and ecological expansion of detrital-chitin producing groups. The convergence of multiple lines of evidence demonstrates the utility of HGT-based dating methods in microbial evolution. The pattern of inheritance of chitinase genes in multiple terrestrial bacterial lineages via HGT processes suggests that these genes, and possibly other genes encoding substrate-specific enzymes, can serve as a “standard candle” for dating microbial lineages across the Tree of Life.

Description: This work was supported by a National Science Foundation (NSF) Graduate Research Fellowship Program Award to DSG., and Simons Collaboration on the Origins of Life Award #339603 and NSF Integrated Earth Systems Program Award #1615426 to GPF. The funding agencies for this study had no role in study design, data collection, data analysis and interpretation, or in writing the manuscript.

Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Millette, N. C., Kelble, C., Linhoss, A., Ashby, S., & Visser, L. Using spatial variability in the rate of change of chlorophyll a to improve water quality management in a subtropical oligotrophic estuary. Estuaries and Coasts, 42(7), (2019): 1792-1803, doi:10.1007/s12237-019-00610-5.

Description: Anthropogenic eutrophication threatens numerous aquatic ecosystems across the globe. Proactive management that prevents a system from becoming eutrophied is more effective and cheaper than restoring a eutrophic system, but detecting early warning signs and problematic nutrient sources in a relatively healthy system can be difficult. The goal of this study was to investigate if rates of change in chlorophyll a and nutrient concentrations at individual stations can be used to identify specific areas that need to be targeted for management. Biscayne Bay is a coastal embayment in southeast Florida with primarily adequate water quality that has experienced rapid human population growth over the last century. Water quality data collected at 48 stations throughout Biscayne Bay over a 20-year period (1995–2014) were examined to identify any water quality trends associated with eutrophication. Chlorophyll a and phosphate concentrations have increased throughout Biscayne Bay, which is a primary indicator of eutrophication. Moreover, chlorophyll a concentrations throughout the northern area, where circulation is restricted, and in nearshore areas of central Biscayne Bay are increasing at a higher rate compared to the rest of the Bay. This suggests increases in chlorophyll a are due to local nutrient sources from the watershed. These areas are also where recent seagrass die-offs have occurred, suggesting an urgent need for management intervention. This is in contrast with the state of Florida listing of Biscayne Bay as a medium priority impaired body of water.

Description: Data provided by the SERC-FIU/SFWMD Water Quality Monitoring Network is supported by SFWMD/SERC Cooperative Agreement #4600000352 as well as EPA Agreement #X7-96410603-3. This research was also funded by a NOAA/Atlantic Oceanographic and Meteorological Laboratory grant to the Northern Gulf Institute (award number NA160AR4320199).

Description: Lake Nakuru is an economically important natural resource in Kenya. Despite the unique ecological characteristics exemplified by this lake, the industrial potential of microbes in the lake has barely been explored. The main objective of this study was to determine the distribution of bacteria, isolate and characterize bacteria with industrial potential. This was achieved through intensive ecological study of three sites on the lake for a period of six months (January to June 2010). Total bacterial counts were determined by direct epifluorescence microscopy of acridine orange stained samples on black polycarbonate filters. Heterotrophic plate counts were plated on 4% NaCl and 1 % Na2CO3 nutrient agar. Enzymatic activities of bacteria towards various macromolecules were investigated for 30 selected isolates by testing their ability to degrade such substrates as starch, cellulose, casein and lipids. The potential use of bacterial isolates for feather degradation was determined by allowing isolates to grow on a feather waste medium as the sole source of carbon and nitrogen. Genomic DNA of four isolates (LNS08, LNC09, LNC11 and LNC06) that showed highest potential to degrade macromolecules and feathers was amplified by PCR and subsequently sequenced. Temperature and pH variations in the lake were low throughout the sampling duration. Dissolved oxygen varied tremendously in the lake with a high value of about 18.4±5.1 mg/l in February and a low mean value of 2.08mg/l in April 2010 when a highest rainfall event occurred and consequently higher total counts (TC) and heterotrophic plate counts (HPC) were recorded. There were significant (P〈0.05) temporal and spatial variations in terms of HPC and TC and this was factored by the rainfall event with the Northern side of the lake being significantly different from the South and Central points. Of the 30 bacterial isolates from Lake Nakuru, 24 showed ability to degrade macromolecules with 26.7% degrading starch, 20% proteins, 16.7% cellulose and 16.6% lipids while for 20% of isolates no enzymatic activity was recorded. DNA analysis revealed identity of four isolates with industrial potential to be closely related to known bacteria viz; Nesterenkonia lacusekhoensis (LNS08), Bacillus agaradhaerens (LNC06) and Bacillus sp. Acc No: AB043860.1(LNC09 and LNC11). Bacillus agaradhaerens showed best potential for industrial application in the degradation of chicken feathers. Bacillus sp. Acc No: AB043860.1has potential industrial production of sugars from starch and cellulose. Nesterenkonia lacusekhoensis is a lipid degrader. The results of this work indicated that Lake Nakuru is a rich source of many alkaliphilic bacteria which could be a good source of interesting enzymes from the industrial point of view.

Description: Masters