Nitrite-oxidation Bacterial Growth without Nitrite source

As we may know bacteria can be helpful or harmful not only to humans but to every living creature. many bacteria have a complex way of compromising with the environment. In our waste water treatment plants numerous distribution of nitrite oxidizing bacteria are present playing a role in the biogeochemical nitrogen cycle. Nitrate oxidation takes place with ammonium and carbon dioxide as an energy source,  a pure culture of N.moscoviensis was placed in nitrate free mineral mediums and replaced the carbon dioxide with hydrogen or oxygen, to be used as an electron donor and acceptor.

Hydrogenotrophic growth of N.moscoviensis with oxygen as terminal electron acceptor.Koch H, Galushko A, Albertsen M, Schintlmeister A, Gruber-Dorninger C, Lucker S et al. (2014).

 

                                                  
Comparisons of growth  in  hydrogen and oxygen rich mediums and  N. moscoviensis  and oxygen were compared leading  to the conclusion that nitrite bacterial growth can be ubiquitous with an aerobic hydrogen oxidation present.

 Reference: 
           Koch H, Galushko A, Albertsen M, Schintlmeister A, Gruber-Dorninger C, Lucker S et al. (2014). Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation. Science 345:1052-1054.

Breathing Life in the Subway

 Hong Kong MTR network map
Courtesy of: Leung, Wilkins, Li, Kong, and Lee (2014)

Few people recognize the amount of life found in the twisting tunnels of a subway, but Leung, M.H.Y. et al. have recognized the importance of determining what types of microbes travel through the air that many commuters in dense cities breath daily in their lives. They tested seven train tracks, collecting the aerosolized microbes during morning peak and non peak hours, as well as during evening peak and non peak hours, over 15 regular weather days. Their study showed that the majority of microbes found in subway were associated with skin, and that the communities within the subway differed based on the architectural characteristics, nearby outdoor micro-biomes, and connectedness with other lines. So, in general while riding the subway keep in mind that you are constantly breathing in a variety of microbial life and that the temperature, humidity and carbon dioxide levels lead to increased abundances of aerosolized microbes. 

So, maybe you should consider walking or riding a bike once in awhile?

Reference: Leung, M.H.Y., Wilkins, D., Li, E.K.T., Kong, F.K.F., and P.K.H. Lee. (2014) Indoor-air microbiome in an urban subway network: diversity and dynamics. Applied and Environmental Microbiology 80(21):6760-6770. 

Triple washed lettuce?

Despite disinfection and hygiene efforts during food production pathogenic bacteria often persist. Foodborne pathogenic bacteria are a major cause of foodborne illness. Cleaning and chemical disinfection may work against some bacteria but not on cyst forming free-living protozoans. cysts are an integral part of the life cycle of many protozoans which allow them to survive adverse environmental conditions. pathogenic bacteria have been shown to survive inside cyst even after exposed to antibiotic treatment or highly acidic conditions. Common and wide spread foodborne pathogenic bacteria like salmonella, E-coli, Yersinia, and listeria were found to survive with up to 53% of amoeba cysts infection and some surviving up to 3 weeks! This suggest protozoa may play a bigger role on foodborne illness and further research on the factors and condition that prevent uptake of foodborne pathogens by protozoa is necessary.

 TEM micrograph of A. Castellanii cyst with (c) E.Coli and (b) L.Monocytogenes  

figure from Lambrecht et al.

Lambrecht E, Baré J, Chavatte N, Bert W, Sabbe K, Houf K. 2015. Protozoan cysts act as a survival niche and protective shelter for foodborne pathogenic bacteria. Appl Environ Microbiol 81:5604–5612. doi:10.1128/AEM.01031-15.

Flying with MRSA!

By: Priscilla Carlo

Corbisimages.com

Planning to take a nice far far away vacation? Maybe an airplane is not the best traveling option. With the constant flow of passengers, bacteria tend to accumulate in certain spots within the aircraft. Research acknowledged by the American Society for Microbiology (ASM), shows that airplanes can carry pathogens such as Escherichia coli 0157 (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA).
Both leading scientist, Dr. Vaglenov and Dr. Barbee from the Auburn University conducted this experiment by replicating the environment of an airplane cabin. These scientist obtained cabin fixtures such as armrests and seat pockets, and also replicated the temperature and humidity inside the cabin. Next, they sterilized and intentionally infected the surfaces of the fixtures with common human pathogens such as E. coli and MRSA in order to mirror the pathogens introduced by human exposure. The results showed that longest living pathogen inside the cabin happens to be MRSA, with a whopping eight days of survival inside of the seat pockets. The seat pockets happens to be the perfect breeding ground from this bacterium; thus, the scientists recommend for the passengers to wash their hands before and after boarding the aircraft. 

                                    

Original Source:
American Society for Microbiology.  (2014, May 20). Where Pathogens Can Linger on Airplanes. [Video File]. Retrieved from http://gm.asm.org/index.php/scientific-activities/asm-live/archives/571-asm-gm-2014-where-pathogens-can-linger-on-airplanes.

Bacteria in Dust

By: Marisol De Leon

There is without a doubt very few instances, if any, where a person is not in contact with a microbe. Maintaining a clean home does not guarantee that it is free of bacteria or fungi as these can be found in dust. In a study done throughout the United States, dust samples from 1100 homes were collected in order to find the fungal and microbial communities found in settled dust. These samples were taken from upper door trim in the main living area and the upper door trim on the outside surface of an exterior door. The study showed that bacteria associated with the skin and faeces such as Streptococcus and bacteroides were more abundant inside homes as was expected. Fungal communities found inside the home varied by climate and geographical regions. Furthermore, bacteria from non-human occupants were also found to be relatively more abundant inside homes. This showed that the composition of bacterial communities found were influenced by the number and types of occupants. As seen in the figure below, 56 and 24 bacterial genera were more abundant in homes with dogs or cats. Also, skin- associated taxa such as Dermobacter were more abundant in homes with fewer women. Lactobacillus was found to be more abundant in homes with women than without women.While trying to eliminate all dust from your home might sound like a good but tiring option, its important to remember that bacteria and fungal communities found in settled dust can depend on the presence and activities of human and non-human occupants as well. 

Figure from Barberan A et al. (2015) shows the differences in proportion of bacteria found in homes with a) dogs or no dogs, b) cats present or absent, and c) homes with more females than males and homes with more males than females.

Barberan A et al. (2015). The ecology of microscopic life in household dust. Proc. R. Soc. B 282: 20151139

Fizzy Drink With a Fuzzy Fungus

Carbonated (fizzy) drinks are a mixture of water, fruit juice, flavorings, and preservatives such as benzoic or citric acid. If the drink has citric acid then it is probably a microbial product. Most citric acid is made by fermenting a sugar, like molasses, with the mold called Aspergillus niger. The specific strain of the fungus used by soda companies is kept secret. Having a precise combination of sugar type and convention, pH, trace metal content, aeration, and salt concentration, can produce the perfect amount of citric acid. The easiest fermentation method used is called the submerged process. Fermintation is carried out in to towers made of stainless steel. The hairy part of the fungus (mycelium) develops into small pellets. This process takes about 7-10 days. The culture broth is then filtrated and the citric acid is extracted and crystallized out and sent to beverage industries to produce your favorite soda!  

Soils naturally suppressive to banana Fusarium wilt disease harbor unique bacterial communities

Panama disease, also known as Fusarium wilt disease, is caused by the fungal soil pathogen Fusarium oxysporium f.sp. cubense. The pathogen infects the root system, the vascular system, and then the leaves of the banana, rendering fruits unconsumable and eventually causing the whole destruction of the tree. Today people around the world consume Cavendish cultivars since the previous cultivar, Gros Michel, was wiped out by F. oxysprorium to the extent that it was discontinued and replaced by Cavendish. Once the banana is infected by the Fusarium, the damage is devastating since it is a monocrop at the plantation level.  Thus, the disease spreads quickly. Shen et al. studied what types of indigenous soil bacteria (i.e. Pseudomonas, Bacillus, Burkholderia) suppress soil diseases and thus protect susceptible crops from soil pathogens.  From the analyses of the soil bacteria, Pseudomonas accounts for the suppression of Fusarium wilt disease.  Also, Gp5 ( Acidobacteria subgroup) was found in abundant amounts in many disease-suppressive soils.  Shen et al. suggests that the abundance of the two bacteria help suppress soil disease and that further studies and application of these bacteria will help reduce the spread of the Fusarium wilt disease.

Fig. 4 The relative abundance of phyla for conducive soil samples collected from the north site (NC),

suppressive soil samples collected from the north site (NS), conducive soil samples collected from the

south site (SC) and suppressive soil samples collected from the south site (SS). Others indicates

extremely low abundant phyla, including Chlorobi, Elusimicrobia, Spirochaetes, Synergistetes, BRC1,

OD1 and OP11

 

 

 

Shen et al. (2015). Soils naturally suppressive to banana Fusarium wilt disease harbor unique bacterial communities. Plant Soil 393:21-33

 

 

 

 

Winter is Coming...So is Flu Season

By: Ashley Garcia 

The time of autumn and winter is upon us and with it the dreaded pathogens that cause sore throats and runny noses. A notable trend has been observed between seasonal changes and influenza outbreaks in much of the northern hemisphere. However, answers on the specific factors that influence this trend have remained ambiguous. A study investigated the climatic and socio-demographic variables that contributed to the H1N1pdm09 outbreak in France in 2009-2010. The investigators collected data such as reported influenza cases, population density, temperature, and demographics throughout France. It was found that low humidity, insolation (UV radiation), and high population density lead to increased host susceptibility and prevalence. An interesting finding was that the degree of interconnectedness between urban cities and rural communities increased the ease of disease transmission rather than distance alone. Nonetheless, the mechanisms that influence these factors need further investigation. This includes influenza transmission in sub-tropical and tropical regions where relative humidity and high temperatures are constant. Our biggest defense against influenza is vaccination, which unfortunately many tend to forgo resulting in a long winter indeed. 

Original Article:

Vittecoq M, Roche B, Cohen JM, Renaud F, Thomas F (2015). Does the weather play a role in the spread of pandemic virus influenza? A study of H1N1pdm09 infections in France during 2009-2010. Epidemiology of Infectious Disease. doi:10.1017/S0950268815000941

Microbes in Extreme Environments

Is there an apparent link between the evolutionary processes of microbial communities and their environments? In order to conclude whether this is true, six different habitats were examined using metagenomics samples to see if the evolutionary process is dependent on the type of microbial community. The results demonstrated that there is a correlation between the evolutionary process and their communities. It was shown that microbes that live in extreme habitats have a capability to evolve faster. Basically, microbes who live in hot springs or saline lakes evolve more rapidly compared to microbes who live in “normal” environments. Microbes living in extreme habitats may evolve quickly due to their constant exposure to stress in their extreme environments. 

Fig. 5 

The figure above demonstrates how there is higher relative evolutionary rates and relative abundance of transposases in extreme microbial environments in comparison to normal environments. 

Cultivating Green Biofuel

By: Gerardo Saldaña

 

Algae had been cultivated during the Second World War, mainly as a food source for nutrient supplement and antibiotics. Not until the 1970’s through today, algae began to play a role as an energy source for gas and electricity. Algae being used as a power source can be beneficial for the environment and it could replace fossil fuels. In order to obtain these microbes, cultivating techniques plays an impact. Algae cultivation might sound simple, but it requires a balance in temperature and water concentration (salts and PH) in order for them to grow. One cultivating method involves large open pond that contains the algae; which makes them exposed to sunlight, the water needs to be replace daily. One aspect is the accumulation of salts if the water concentration is not balanced; too much salt can be crucial for growth. The other method is the enclosed photo-bioreactor (no sunlight) which contains the microbes and provides nutrients that they need. The bioreactor has a pump that is connected to the chemostat, the pump circulates the substrate as needed. In this process the substrate will always be provided, unlike the open pond which algae produce their food by sunlight (autotrophs). Algae can be an excellent biofuel, it does not harm the environment and is efficient.

                                                                     A open pond                                        Image by Google

                                                                                           A Enclosed photo-bioreactor                          Image by Google

Original Article: Murphy CF, Allen DT. (2011). Energy-water nexus for mass cultivation of algae. Environ.Sci. Technol 45: 5861-5868

Catering to Bacteria

                                                                                       Image by Google

By EmmaJo A. Robledo

 

The food industry has come a long way in its hygiene practices with regulations on food, sanitizing, facility, equipment, and uniforms.On a study conducted on 153 events and over a thousand samples it was shown that hygienic and disinfecting practices have greatly improved bacteria control as compared to last year. In the study, it was shown that over half of the wristbands from servers was infected with Escherichia coli and some form of staphylococci due to the fabric of the band. This particular study was designed with the coming London Olympics in mind. Researchers were studying the various procedures and policies placed in order to control bacterial growth at large events and gatherings. Understanding how we cater to bacteria at such large events will better assist us in setting fourth control measures in order to prevent a large pathogenic outbreak in the future.

 

Willis C, Elviss N, Mclauchlin J. (2014). A follow-up study of hygiene in catering premises at large-scale events in the United Kingdom. J Appl Microbiol Journal of Applied Microbiology 222–232.

Microbe-Flavored Wine!

By: Nathan Campos

  

It has always been said that vineyard location plays a big role in the terrior, or characteristics, of any fine wine.  According to researchers from the University of Auckland in New Zealand, there is some truth to the speculation.  After isolating the six major strains of Saccharomyces cerevisiae found in New Zealand’s six wine-producing regions, researchers individually inoculated the 36 strains into sterilized samples of Sauvignon Blanc grape juice in order to induce fermentation.  Each wine sample was tested for the presence and levels of 39 specific compounds, as well as the amount of ethanol, sugar, and acidity.  While there was an overlap in the chemical signatures of the wines, there were much closer similarities observed in the yeast strains of wines found in the same region.  Interestingly enough, the wines produced in the Nelson region of New Zealand all displayed high concentrations of compounds that have generally been known to bestow an apple or sweet fruit aroma and taste to the wine.  The implications of the experiment are significant; theoretically, scientists could manipulate strains of yeast in conjunction with other terrior-affecting factors, and can create the perfect wine regardless of the wine’s age.

        

S. Knight et al., “Regional microbial signatures positively correlate with differential wine phenotypes: evidence for a microbial aspect to terroir,” Scientific Reports, 5:14233, doi:10.1038/srep14233, 2015.