Listeria monocytogenes is a kind of bacterium that sometimes causes disease in people (recently transmitted on melons mostly, for some reason). It’s notable for being able to proliferate at relatively low temperatures, and can also get inside our cells and spread from cell to cell, even infecting the central nervous system, causing meningitis. Most of the time it lives in the soil, and can swim around with several flagella. People have wondered whether certain kinds of amoebas in the soil, such as Acanthamoeba, may be infected by Listeria and help it to maintain its presence in the environment. On the other hand, Acanthamoeba is known to feed on some kinds of bacteria, so it may actually reduce the numbers of Listeria. A study being published in Environmental Microbiology recently provided evidence supporting the latter case, showing that the amoebas actually carry Listeria and other bacteria around on their cell surface as a portable food source! First, to show that Listeria does not survive or multiply inside Acanthamoeba, the scientists mixed wild-type L. monocytogenes, a more virulent strain, and the harmless strain L. innocua with two species of Acanthamoeba, let them interact for a while, then killed all bacteria outside the amoebas with an antibiotic and lysed the cells to free any bacteria that might be inside them so they could be counted. They found that none of the bacteria survived inside the amoebas. What they did see, using bacteria producing fluorescent protein, was that Acanthamoeba had bacteria sticking to its backside for a while, up to half an hour, until the amoeba took them up into itself, holding them in a special chamber called a vacuole, where it could digest and consume them. There’s a very cool video showing this process on the paper’s website that I’ll link to. The bacteria were never observed escaping into the cytoplasm of the amoeba. The researchers called the clumps of bacteria sticking to the amoebas “backpacks,” made up of up to hundreds of cells “hitchhiking” on the amoebas. They wondered what was causing the bacteria to stick to the amoebas; it wasn’t any particular pathogenicity factor, since strains lacking each of them still formed backpacks. Then they discovered that Listeria grown at 37 degrees C, in which condition it does not make flagella, did not form backpacks. So they tested several strains that either did not make flagella or made them but could not move them, and found that none of these made backpacks on Acanthamoeba. So apparently it’s not just the presence of flagella that is necessary; they must actually be moving. Backpack formation wasn’t limited to Listeria though: other kinds of motile bacteria that the scientists tested also formed backpacks on Acanthamoeba. Non-motile species did not, of course. Also, other amoebas besides Acanthamoeba didn’t produce backpacks either. Under an electron microscope, the bacteria seemed to be entangled in some tiny filaments extending from the surface of the amoeba, though the scientists did not figure out what the nature of these filaments was. That and the reason behind the need for motility were left for future studies. This study was useful enough, though; it’s good to know how pathogens interact with other microbes in the environment, so we can possibly get a better idea of how outbreaks occur and how to prevent them. I also thought this study was just kinda funny and interesting; the amoebas are carrying around the food they caught to munch on when they get hungry. I wonder if there might be some advantage to the bacteria, though, to prevent them from adapting to this backpacking strategy, which it seems like they could easily do by turning off their flagellar motors; maybe some can escape from backpack before being eaten, after being carried to a new environment where they can proliferate. It’s possible that having functional flagella is beneficial enough that it outweighs the risk of being captured by an amoeba. Microbes are pretty interesting!

Listeria monocytogenes is a kind of bacterium that ...

proliferate at relatively low temperatures, and can also get inside our cells and spread from cell to cell, even infecting the central ... Microbes are pretty interesting!

11KB Sizes 0 Downloads 205 Views

Recommend Documents

for Detection of Listeria monocytogenes
... Palm Instrument (BZ. Houten, Netherlands). Fig. 1. Apparatus and immunosensing processes of the SPCE. Reagents and solutions. Ethanol (100%) was obtained from Pharmco-Aaper (Brookfield, CT). Sodium citrate. (C6H5Na3O7), hydrogen peroxide (H2O2),

for Detection of Listeria monocytogenes
applications in the food and water industries (Lin et al., 2008). ... ability to amplify the detection signal, improve the electron transducer, and reduce the detection ...

Submission Deadline What kind of opportunity is this ...
and Applications. (SGDA 2013). Trondheim,. Norway. 25-27. September. 2013 .... Decision Analytics,. Mobile Services and. Service Science. Digital and Social.

Join us for a one-of-a-kind professional development opportunity that ...
www.top20training.com or contact Becky Cain at [email protected] ... Call about requests for alternative formats and/or interpreters: Disk, Braille, Large Print, Interpreter, ... July 20-21- Sioux Falls - Denny Sanford Convention Center.

Submission Deadline What kind of opportunity is this ...
May 8, 2013 - MindTrek Association,. City of Tampere,. Tampere University of. Technology (TUT),. Tampere University. (UTA), Tampere. University of Applied. Sciences (TAMK),. Ambient Media. Association (AMEA). Academic MindTrek. 2013. Tampere,. Finlan

"Knowledge is that which ..." "Knowledge is that ... -
what the Messenger [. ىلص. ملس و هيلع الله. , may Allah exalt his mention and render him and his message safe from every derogatory thing ] came with".

A New Kind of Science - Scott Aaronson
³8 &k k@®5 q@²! daq@m ²Aknh3 fa³8 ¯E³8m8m hgk@ " q " qi ²0faq)eg ..... q@ zfgk ¯Eh £q@m8 q@h3 ¨ ¶ mµzk ³8h U¾faq)eg a eaz Ag§gk@p0q@hg§gknr & p" ...

A Better Kind of Consulting -
Company. How to Become Involved. •. Visit www.mbinterim.com and complete the online registration form. A Sampling of MBIL's Clientele. Angela Anderson.

It's Kind of a Funny Story.pdf
It's Kind of a Funny Story.pdf. It's Kind of a Funny Story.pdf. Open. Extract. Open with. Sign In. Main menu. Displaying It's Kind of a Funny Story.pdf. Page 1 of 2.

Ned Vizzini - It's kind of a funny story.pdf
Whoops! There was a problem loading more pages. Retrying... Ned Vizzini - It's kind of a funny story.pdf. Ned Vizzini - It's kind of a funny story.pdf. Open. Extract.

Postsecondary Enrollment Options (PSEO) is a program that allows ...
and 12th-grade students to earn both high school and college credit while still in ... courses are offered online. ... take one career/technical PSEO course.

Is that a bathtub in your kitchen? - Nature
Princeton University, Princeton, New Jersey, USA. e-mail: [email protected] or [email protected] ... cortex may support this ability. These regions, defined by their strong response to intact as ... objects in a scene can be used to support

Is Core Affect a Natural Kind? John Jenkinson Many ...
affect and its role in emotional episodes. .... vary over time (or space), while t continues to have the same definition (Boyd. 1999, 144). Further, not all of the members of class of homeostatic property clusters need to share exactly the ..... Pank

PDF A New Kind Of Science Full Books
A New Kind of Science Challenging the traditional mathematical model of scientific ... Deep Learning (Adaptive Computation and Machine Learning Series).

ePub A New Kind Of Science Read Online
Bayes' Rule: A Tutorial Introduction to Bayesian Analysis · Reinforcement Learning: An Introduction (Adaptive Computation and Machine Learning series).

Read Online A Different Kind of Animal
Read Online A Different Kind of Animal: How Culture. Transformed Our Species (The University Center for Human. Values Series) Free epub ...

Is that a bathtub in your kitchen?
Princeton University, Princeton, New Jersey, USA. e-mail: ... [email protected] ..... protein–containing complex and activation of the MAP kinase signaling ...