5 Interesting Microbiology News

1. Blowing out birthday candles increases cake bacteria by 1,400 percent

“Due to the transfer of oral bacteria to icing by blowing out birthday candles, the transfer of bacteria and other microorganisms from the respiratory tract of a person blowing out candles to food consumed by others is likely.”
Read more: http://www.ccsenet.org/journal/index.php/jfr/article/view/67217

2. Investigators use light to kill Gram-positive bacteria

Gram-positive bacteria cause the majority of skin and soft tissue infections (SSTIs), resulting in the most common reason for clinic visits in the United States. Recently, it was discovered that Gram-positive pathogens use a unique heme biosynthesis pathway, which implicates this pathway as a target for development of antibacterial therapies.
Read more: http://www.pnas.org/content/early/2017/07/19/1700469114.full

3. Hybrid yeast new to science found in self-fermented beer

“The hybrid appears to be a recent hybridization event between Pichia membranifaciens and a previously undescribed species approximately 10-20 million years divergent.”
Read more: http://www.biorxiv.org/content/early/2017/06/15/150722

4. Woman died from tick disease through a cat bite

“The woman was reportedly caring for a sick stray cat. Just ten days after, she died from a condition known as Severe Fever with Thrombocytopenia Syndrome (SFTS).”          Read more: https://www.labroots.com/trending/clinical-and-molecular-dx/6569/diagnosed-woman-died-tick-disease-cat-bite

5. Cryptosporidium outbreaks linked to swimming have doubled since 2014

“Diarrhea caused by the parasite is a problem for swimming pools and water playgrounds.”
Read more: https://www.cdc.gov/media/releases/2017/p0518-cryptosporidium-outbreaks.html

Your Regularly Cleaned Kitchen Sponge May Be Dirtier Than You Think

It’s already common sense that kitchen sponges are a reservoir of bacteria.

One solution that has been presented to us over the years is their sanitization, by boiling or even microwaving them, for example. However, according to a recently published study, it was found that regularly sanitized sponges had the same quantity of bacteria as non-sanitized sponges, and also an increased abundance of bacteria related to pathogens. This increase in abundance may be due to the survival of resistant bacteria after sanitation, leaving the sponge free of competition and available to be quickly recolonized.

(A) Kitchen sponges, due to their porous nature (evident under the binocular; (B)) and water-soaking capacity, represent ideal incubators for microorganisms. Scale bar (B): 1 mm. (C) Pie charts showing the taxonomic composition of the bacterial kitchen sponge microbiome, as delivered by pyrosequencing of 16S rRNA gene libraries of 28 sponge samples (top and bottom samples of 14 sponges, respectively). For better readability, only the 20 most abundant orders and families are listed.
(A) Kitchen sponges, due to their porous nature (evident under the binocular; (B)) and water-soaking capacity, represent ideal incubators for microorganisms. Scale bar (B): 1 mm. (C) Pie charts showing the taxonomic composition of the bacterial kitchen sponge microbiome, as delivered by pyrosequencing of 16S rRNA gene libraries of 28 sponge samples (top and bottom samples of 14 sponges, respectively). For better readability, only the 20 most abundant orders and families are listed.

The study also emphasizes the presence of a Gram-negative bacterium, Moraxella osloensis, capable of causing infection in immunocompromised people, especially cancer patients, and, curiously, responsible for the characteristic smell of locker-rooms, leading to the hypothesis that “ cleaned sponges might paradoxically smell more often”.
The importance of this study is related to the fact that kitchen sponges act as bacteria disseminators, which in turn “can lead to cross–contamination of hands and food, which is considered a main cause of food–borne disease outbreaks”.

Finally, the solution presented by the scientists is simple – replace kitchen sponges regularly, for example, every week.

Gram-positive or Gram-negative Bacteria – What Does This Mean?

Gram-positive or Gram-negative bacteria – What Does This Mean?
When we read about bacteria in the media, we often come across the term gram-positive or gram-negative bacteria. But what does this mean?

Actually, Gram is the name given to a technique developed in 1884 by a Danish doctor named Hans Christian Joachim Gram. The popularity of this technique is due to the fact that it allows to quickly differentiate bacteria according to a characteristic of its cell wall: the amount of peptidoglycan. In fact, Gram-positive bacteria have a relatively thick layer of peptidoglycan in their cell wall, while Gram-negative bacteria have only a small layer which is dissolved during the procedure, being unable to retain the applied dye. Thus, Gram-positive bacteria are characterized by their purple color when viewed under the microscope, after applying the Gram staining, while the Gram-negative bacteria present a pink color.

microscopic image of a Gram stain of mixed Gram-positive cocci (Staphylococcus aureus ATCC 25923, purple) and Gram-negative bacilli (Escherichia coli ATCC 11775, pink)
Microscopic image of a Gram stain of mixed Gram-positive cocci (Staphylococcus aureus ATCC 25923, purple) and Gram-negative bacilli (Escherichia coli ATCC 11775, pink) By Y tambe – Y tambe’s file, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9999296

At the clinical level, this method will allow distinguishing whether an infection is of bacterial origin and provide additional information by distinguishing between Gram-positive or negative bacteria (Gram-negative bacteria tend to cause more serious diseases comparatively to Gram-positive bacteria). You can also obtain information about the size, amount and shape of the bacteria present in the smear, allowing the health professional to monitor the infection, and apply a treatment until other diagnostic tests are complete, if necessary, taking into account that the Gram stain alone is not sufficient for the identification of the bacterial species.

 

Food Choice Controlled by Bacteria in Host

According to a study made by researchers at the Champalimaud Foundation, the interaction between specific nutrients and microbiota (microorganisms living in the host’s intestine) has the ability to model the behavior and demand of certain foods in animals. This interaction was studied in Drosophila melanogaster, a fly that feeds on yeasts to obtain protein.

Knowing that animals, including humans, alter eating behavior in order to control protein intake, researchers observed that, faced with a deficiency in essential amino acids, there were differences in behavior between flies according to the bacteria in their microbiota.
In summary, the lack of essential amino acids induced a strong appetite for foods rich in proteins or amino acids in microbiota-free Drosophila, as well as a reduction of their reproduction. On the other hand, in Drosophila whose microbiota specifically included the bacteria Acetobacter pomorum and Lactobacilli, a lower appetite for protein rich foods was observed and also recovery of their reproductive activity, thus demonstrating the influence of bacteria on physiology and behavior of their host, in this case, caused by Acetobacter pomorum working together with Lactobacillus plantarum or Lactobacillus brevis changing food choice of the flies.

The importance of this study is related to the big impact of diet on human health, with the “interaction of the microbiota with ingested nutrients being a major determinant of health and disease, including obesity”. It has been proposed that bacteria of the intestinal flora can even affect brain functions such as anxiety and social behavior.

 

Source: Leitão-Gonçalves R, Carvalho-Santos Z, Francisco AP, Fioreze GT, Anjos M, Baltazar C, et al. (2017) Commensal bacteria and essential amino acids control food choice behavior and reproduction. PLoS Biol 15(4): e2000862. https://doi.org/10.1371/journal.pbio.2000862

Scientists Stored a GIF in DNA of Living Bacteria

A team of scientists from Harvard University was able to successfully introduce a GIF into the genome of live Escherichia coli bacteria.

The GIF, an image with movement of a horse and its rider in black and white, was divided into 5 frames of which each pixel was encoded into nucleotides and placed into the DNA of the bacterium, using the CRISPR–Cas method. This method is based on the utilization of the bacteria’s adaptive immune system, in short, consisting of inserting small DNA sequences into its genome. This intrinsic defense mechanism of bacteria arose from a need to defend themselves against viruses, allowing the cell to recognize and eliminate infections.

Finally, the DNA sequencing of the bacteria allowed the scientists to reproduce the image with 90% accuracy, confirming the success of the experiment. According to the study, it has been shown that this system has the ability to capture and store information into the genome of living cells in a stable manner.

Taking into account the microscopic size of bacteria and the large information storage capacity of DNA, this technique may allow a large amount of information to be stored in a small compact space in the future, the aim of the scientists being the creation of tiny information “recorders” that can monitor the environment in which they are inserted, over time.

How To Grow a Virus

Viruses are infectious agents that multiply exclusively in living host cells. There are a lot of diseases resulting from viral infections so their diagnosis becomes fundamental. One of the techniques most widely used nowadays for demonstrating the virus presence involves its culture. In the past, this was obtained by inoculating viruses into embryonated eggs or even into animals, because of their inability to multiply externally to living cells. However, cultures are now mostly used in cell systems.

In order to grow a virus, we need a living cell monolayer or suspension, which are themselves cultured in vitro or derived directly from the animal source, such as kidney rabbit cells, used to grow Herpes Simplex virus. Cells grown in vitro include, for example, hematopoietic cells (i.e., cells that give rise to all cells present in the blood, by a process called hematopoiesis) derived from blood, or from the umbilical cord. These cells are useful for culturing viruses such as HIV, although the preferred diagnostic technique for this virus is the identification of antibodies through a blood test since viral culture demands a relatively long time until virus identification is possible.

Viral culture is a virus detection technique that is distinguished from other techniques, such as those based on nucleic acids, due to the fact that by placing a sample in a living cell culture we will obtain not just the virus isolate that we intended to characterize in the first place, but also viruses that were in the sample and that we did not suspect initially, allowing us to store and/or characterized them later.

Further viruses responsible for causing infection in humans, which may be identified by viral culture, include:

 

Reference: Knipe, D.M., Howley, P.M (2007) Fields Virology, Philadelphia: Lippincott Williams & Wilkins

Teixobactin and the Battle Against Antibiotic Resistance

Teixobactin is an antibiotic, consisting of a small molecule, effective against gram-positive bacteria. It’s worthy of mention due to two special characteristics, according to a study published by a team of scientists from the University of Northeastern:

  • it effectively eliminated Staphylococcus aureus and Mycobacterium tuberculosis without originating resistant strains;
  • its discovery was coupled with the development of the iChip, an innovative technology that promises to revolutionize the discovery of new antibiotics.

Bacteria resistance to antibiotics is a public health concern, which has been worsening in recent years, since the introduction of antibiotics in 1940. The development of resistance by some bacteria, such as MRSA (methicillin-resistant Staphylococcus aureus), is leading to the necessity of discovering new antibiotics that are capable of eliminating them.

Teixobactin acts by inhibiting cell wall synthesis, by binding to lipid II, a peptidoglycan precursor, thus inhibiting the production of the cell wall peptidoglycan layer, which results in lysis of the bacteria. There are other antibiotics that also act on the cell wall of bacteria, such as Vancomycin. However, there are already strains of bacteria resistant to this antibiotic, such as VRSA (Vancomycin-resistant Staphylococcus aureus), thus the importance of this finding.

The technology used to discover this new antibiotic is also worthy of note. It’s called iChip, and it’s a piece made of plastic that allows bacteria to be enclosed by small pores, large enough for the nutrients to enter and the metabolic waste to escape.The chip is plunged into a sample of bacterial culture mixed with agar, in order to capture it in each well, locked with diffusion membranes and, finally, placed in a medium with the natural environment of the bacteria.The bacteria used to produce this antibiotic is called Eleftheria terrae, and a sample of marine sediments was used as a natural environment. The use of the natural environment of the bacteria is what allows the great success and innovation of this technique, since it’s estimated that about 99% of the bacterial species do not grow in traditional growth medium, such as agar plates. Therefore, if new growth methods were not to be developed, we would have a large gap in the investigation of the substances produced by microorganisms which, like Teixobactin, may have antimicrobial properties, knowing that most natural antibiotics were discovered by investigating soil microorganisms.

The discovery of Teixobactin, while maintaining the need for more studies to ensure it’s safe for human utilization, is a step forward in the discovery of a new class of antibiotics, associated with the discovery of a new bacterial growth technology, which could have a great impact not just regarding the discovery of new antibiotics, but also on the production of other compounds with a wide range of usefulness at the pharmaceutical level.