Antibiotic Outbreak?

By: Dominic Jackson-Anasson

There has been an increasingly number of antibiotic resistant bacteria (ARB) that have become present in our aquatic environments. This is the result of the medications that doctors prescribe to people for infections and other sicknesses. The more antibiotic medication is used the more bacteria build a resistance to it and reproduce. Glady-Croue and colleagues did a study to see if artificial solar radiation would kill the ARB in waste water and it did not. In fact, it killed a lot of environmental bacteria but after the artificial solar radiation the ARB had a higher count than they did before the treatment. This means that the bacteria that was resistant to the radiation was also resistant to antibiotic drugs. Now knowing this we can see that ARB bacteria will be harder to kill, this will mean possible new drugs that need to be made to kill them, other lab ways to kill the bacteria, and new ways will be needed to find the bacteria so that we don't consume them.


Figure 1: Shows a simple diagram of what happened during the experiment.

Original Article:
Glady-Croue J, Niu X-Z, Ramsay JP, Watkin E, Murphy RJT, Croue J-P. (2018). Survival of antibiotic resistant bacteria following artificial solar radiation of secondary wastewater effluent. Science of The Total Environment. https://www.sciencedirect.com/science/article/pii/S0048969718301219 (Accessed October 25, 2019).

Got Fungus?

By: Andrea G. Gloria

Fungal Species Accumulation Curves. Average fungal OTU richness for two seasons (summer and winter), three wood types (pine, spruce and mix of pine and spruce) (a), 11 different sawmills, and five departments: maintenance (M), planing (P), saw (S), sorting of green timber (SGT) and sorting of dry timber (SDT) (c). Figure taken from Straumfors et al., 2019.

Although it is known that fungal exposure is linked to respiratory symptoms and allergic alveolitis among sawmill workers, there is limited research on the characterization and diversity of the fungi (Straumfors et al., 2019). In order to gain a better understanding of exposure-response relationships, Straumfors and colleagues utilized metabarcoding of fungal DNA from air samples obtained from 11 workers from Norwegian sawmills, sorting and planer mills. This allowed the researchers to study differences in richness, diversity and taxonomic composition of the fungi between various companies, departments, wood types, and seasons. As seen in the figure, workers were exposed to a higher amount of operational taxonomic units (OTUs) in the summer and when processing spruce (a). Fungal exposure also varied amongst departments, with workers in the saw department being the highest (c). This study shows that fungal inhalable exposure may vary between season, wood type, companies and departments. The evidence may suggest that exposure-related health effects may also be different. Further research may expand the knowledge of species pathogenic to humans and allow more accurate risk assessments for workers. 

Original Article: Straumfors A, Foss OAH, Fuss J, Mollerup SK, Kauserud H, Mundra S. 2019. The inhalable mycobiome of sawmill workers: exposure characterization and diversity. Appl Environ Microbiol 85:e01448-19. https://doi .org/10.1128/AEM.01448-19.

Abundance of Vibrio parahaemolyticus in Seafood

By: Daniel Cuellar

Salinity percentages display an association with V. parahaemolyticus abundance during different seasons (Spring, Summer, and Fall). Various temperatures relative to the abundance of the bacterium exhibits a linearity during Autumn. Summer temperatures show an increase in abundance but a level-off can be observed. Figure taken from Davis et al. 2017.

Consumption of seafood such as shellfish has shown to be the one of the leading causes of seafood-borne illnesses to thousands of individuals. Vibro parahaemolyticus is the bacterium commonly found with the exposure of shellfish that's either undercooked or raw. Unfortunately, V. parahaemolyticus continues to increase in coastal waters. On the other hand, various ecological studies have shown to have bacterium-abundance connection with factors in the environment. A study performed by Davis and colleagues obtained the significance in understanding these environmental factors such as temperature and salinity (salt concentration). Water temperatures and turbidity have shown to be an indication of abundance of the bacterium. Experiments conducted with mediums that are nutrient rich appeared to exhibit different levels in salinity and temperatures showing a decrease in abundance when salinity levels were high and when water temperatures were cool. In addition, the abundance of V. parahaemolyticus shows an association with warmer areas as it continues to show growth. Although there is no stopping the bacterium from appearing in these costal waters worldwide, researchers have a better understanding of the abundance and persistence but may be essential for developing future forecasts of where to obtain seafoods and prevention of the illnesses from spreading.

Original Article: 
Davis, B., Jacobs, J., Davis, M., Schwab, K., DePaola, A., & Curriero, F. (2017). Environmental determinants of vibrio parahaemolyticus in the chesapeake bay. Applied and Environmental Microbiology, 83(21). doi:10.1128/AEM.01147-17

Soil moisture and its effects of climate warming on photosynthesis

Figure 1: Photosynthesis is reduced by drying soils and climate warming. (Courtesy - Reich P. B. et al. 2018)

Altering soil moisture and thermal effects can induce climate warming which influences photosynthesis. These effects play a vital role in global forests where soil moisture reduces carbon gain and cool temperatures reduce photosynthesis. Higher temperatures can increase enzymatic limits of photosynthesis, if and when low soil water causes stomatal closure and limitation of the carbon dioxide substrate for photosynthesis. Mid and higher latitude plants will experience both the positive and negative effects of climate warming on photosynthesis. Reich P. B. and his colleagues conducted a research to show that the plants will receive positive effects of climate warming if soil moisture is ample and the effects will be negative if soils are drier. Eventually such effects are depended on the balance of time. Low soil moisture has a moderate effect on the photosynthetic enhancement that results from experimental warming (Reich P. B. et al. 2018). In future when the earth will become warmer, it will lead strong stomatal limitations of photosynthesis and higher evapotranspiration will lower the soil moisture and decrease the net photosynthesis. Either it is extremely cold or extremely hot, the plants will have less photosynthesis. Thus maintaining a stable climate temperature should be one of the primary concerns nowadays.



Original article:

Reich, P. B., Sendall, K. M., Stefanski, A., Rich, R. L., Hobbie, S. E., & Montgomery, R. A. (2018). Effects of climate warming on photosynthesis in boreal tree species depend on soil moisture. Nature. doi:10.1038/s41586-018-0582-4 

A Gateway to Antibiotic Resistance: Heavy Metals

By: Alexandra Ortiz

Heavy Metal Antibiotic-Resistant Superbugs. Schematic of the observed mechanisms in heavy metal stimulated transfer of antibiotic resistance. Sub-lethal concentrations of Copper (Cu), Silver (Ag), Chromium (Cr), and Zinc (Zn) were found to stimulate the transfer of antibiotic resistance genes between a donor E.coli and recipient E.coli strain (1) by the production of unstable oxygen molecules (2) and increase in membrane permeability (3). Mobile genetic elements such as plasmids can be transferred between bacteria when exposed to heavy metals at sub-lethal concentrations. (Figure Source: Ortiz, 2019).  

Despite the rise of antibiotic resistance being attributed to the overuse and misuse of antibiotics, scientists are discovering that chemicals other than antibiotics, such as heavy metals, can stimulate antibiotic resistance. Although naturally present in the environment, anthropogenic activities accelerate the release and accumulation of heavy metals into the environment. Zhang and colleagues found that heavy metals such as copper, silver, chromium, and zinc below lethal levels can promote the exchange of antibiotic resistance genes (ARGs) between two E. coli strains. Different mechanisms such as the production of unstable oxygen molecules, increased cell membrane permeability, and altered expression of transfer relevant genes were investigated to understand how heavy metals drive bacteria to become antibiotic-resistant. It was observed that transfer of ARGs increased as the concentration of metals increased (1). Furthermore, levels of unstable oxygen molecules increased significantly as a result of elevated metal ion concentration exposure (2). They also determined an upsurge in membrane permeability as a result of a loss of membrane integrity. It was found that certain sub-lethal concentrations of heavy metals upregulated the expression of these protein channels, resulting in a more permeable membrane that can readily uptake ARGs (3). With the rise of antibiotic-resistant bacterial infections rising, remediation strategies should be assessed to prevent heavy metal stimulated uptake of ARGs by bacteria.

Original Article: 

Zhang, Y., Gu, A.G., Cen, T., Li, X., He, M., Li, D., and J. Chen. (2018). Sub-inhibitory concentrations of heavy metals facilitate the horizontal transfer of plasmid-mediated antibiotic resistance genes in water environment. Environmental Pollution. 237:74-82. 

What's The Fracking Impact?

By: Elia Duron

Figure 1. The effects of the addition of 2,2-dibromo-3-nitriloprorionamide (DBNPA) on the abundance of 16S rRNA gene copies/ml over time in the studied clusters of streams that have either been impacted by hydraulic fracturing (HF+), or unimpacted by hydraulic fracturing (HF-). Figure taken from Campa et al. 2019.

Unconventional oil and gas (UOG) extraction is a method used to allow oil and gas to flow from tight sands that we cannot get to when using the conventional method of drilling. The process consists of drilling down, then horizontally to the point where fracking occurs. Pressurized liquid made up of sand, water, and chemicals cause fractures to the rock below, which causes the fracking process. One of the second most used biocides in the UOG process is 2,2-dibromo-2-nitrilopropionamide (DBNPA). The DBNPA biocide has both toxic and nontoxic properties, so the study performed by Campa and her colleagues strived to understand the response for stream microbial communities to the DBNPA biocide. The 16s rRNA gene copies from LL and NH streams impacted by hydraulic fracturing (HF+) decreased after 7 days of adding the DBNPA biocide, while the EE and WE streams that were un-impacted by hydraulic fracturing (HF-) experienced an increase. The decrease after addition of DBNPA in the HF+ microcosms indicates that the HF+ was sensitive to the biocide. However, in days 56 where the biocide was least present, HF+ had the overall greatest number of gene copies/ml than HF- microcosms. Despite the negative effects that the biocide had in the introduction phase in HF+ microcosms, the numbers of 16s rRNA gene copies show that there is an overall environmental tolerance to high concentrations of DBNPA, meaning that the biocide isn't as effective in controlling complex and dynamic microbial communities.


Original article:
Campa M, Techtmann S, Ladd M, Yan J, Patterson M, Garcia A, et al. (2019). Surface Water Microbial Community Response to the Biocide 2,2-Dibromo-3-Nitrilopropionamide, Used in Unconventional Oil and Gas Extraction. Applied and Environmental Microbiology, 85(21). doi:10.1128/AEM.01336-19

Environment-Friendly Antibiofouling Solution

Figure shows the different materials used, (a) glass slides, (b) filter paper, (c) heavy duty absorbing wipes, (d) Kleenex tissue.


Fouling is the accumulation of bacteria or other microorganisms. It is a problem in a variaty of applications, the clearest example would be in maritime structures like oil rigs and ships. Fouling materials can deteriorate the structure and lead to failure, costing a lot of money in repairs. Biocidal materials like primers and paints are used to prevent fouling, but these paints later leach toxic molecules into the marine environment causing damage to the ecosystem. The focus on superhydrophobic surfaces has increased as it is a much more environment-friendly way to prevent fouling. Hydrophobic surfaces are used as antibacterial, antifogging, anti-icing, and other ways because of its water-repellent properties. Seyed Mohammad Reza Razavi and his team from the University of Illinois came up with a solution using superhydrophobic coating to prevent fouling. The team created superhydrophobic and antibiofouling coatings, adaptable to various surfaces, using fatty acids from cinnamon and myristica. The team used Escherichia coli, to represent Gram-negative bacterium, and Staphylococcus epidermidis as Gram-positive bacterium representative. These bacteria were used to test the attachment of Gram-positive and Gram-negative bacteria on treated and untreated surfaces as shown on the image above. The tests showed that coated surfaces had much lower attachment rates of bacteria.