Name: Measurement of the Acid-Resistant Fluorescent Reporter Protein mCherry2
Uploaded: 2023-06-23T13:30:00
Description: Watch this Scientific Journal Video about Measurement of the Acid-Resistant Fluorescent Reporter Protein mCherry2 at JoVE.com

measurement of the acid-resistant fluorescent reporter protein mcherry2

Measurement of Reporter Proteins in Limosilactobacillus reuteri DSM20016

The genus Lactobacillus were historically classified as gram-positive, rod-shaped, non-spore-forming, either facultative anaerobes or microaerophiles that break sugars down to primarily produce lactic acid1. These loose criteria led to Lactobacillus being, phenotypically and genotypically, an extremely diverse genus. This broad categorization resulted in the genus being reclassified, introducing 23 novel genera in 20202.
The old, broader genus included major commensal and probiotic species generally regarded as safe (GRAS) for consumption3. The Lactobacillaceae family maintains a public perception of being &#39;good bacteria&#39; due to many reported health benefits bestowed via the consumption of various strains4,5,6,7. The ease with which they can navigate the gastrointestinal tract8 and their public acceptance combine to position Lactobacillaceae strains as strong candidates as chassis organisms for ingestible medicinal, therapeutic, or diagnostic applications.
The wide range of characteristics present within the Lactobacillaceae family has led to a situation in which there is no de facto model-organism strain; research groups have tended to select species with the properties most relevant to their particular aims. (For example, dairy fermentation labs could choose L. lactis; studies of vegetable fermentation might select L. plantarum; research on probiotics might focus on L. acidophilus; and so on.)
This same wide range of characteristics across species has led to an accumulation of protocols and procedures that may work well for one subset of the Lactobacillaceae family, but require optimization to work efficiently (or perhaps to function at all) in others9. This need for optimization between family members and even within members of the same species can frustrate the efforts of unfamiliar researchers. Protocols published in the methods sections of papers can also include their own modifications10, leading to fragmented, decentralized protocol collections.
L. reuteri is considered a widely vertebrate commensal, found consistently in mammalian, avian11 and fish12 gastrointestinal (GI) tracts. L. reuteri sub-strains are often genetically specialized, via mucus adhesion protein adaptation, to more permanently colonize specific native hosts8,11,13. GI tract Limosilactobacillus species can be isolated in hosts outside their native host, but tend more toward a transient nature8.
Due to human-host specialization, L. reuteri DSM20016 positions itself very well as a chassis for diagnostic or therapeutic applications at any point in the human GI tract, and the strain DSM20016 could provide a longer-lasting window of effect for interventions when compared to more transitory strains.
In this paper, we outline a series of protocols with demonstrated effectiveness in Limosilactobacillus reuteri (strain designation: F275; other collection numbers: DSM20016, ATCC23272, CIP109823), along with centralized information on the strain from other sources to aid in molecular and systems biology applications. Procedures laid out herein should enable a researcher with no prior experience to culture L. reuteri, create electrocompetent stocks, select transformed colonies, confirm transformation via colony polymerase chain reaction (PCR), and measure designed system response via fluorescent reporter proteins.
We note that related protocols have covered CRISPR-Cas9 assisted ssDNA genome recombineering in L. reuteri (strain: ATCC-PTA-6475)14, and CRSIPR-Cas9 nickase-assisted genome editing in multiple non-L. reuteri, Lactobacillaceae family stains15,16; these do not, however, address the L. reuteri DSM20016 strain that is our focus here.

Author Spotlight: Methods for Electroporation and Transformation Confirmation in Limosilactobacillus reuteri DSM20016  

Métodos para la electroporación y confirmación de transformación en Limosilactobacillus reuteri DSM20016

L.Reuteri, and specifically the strain, DSM20016 is a robust, natural human gut commensal, with great promise for therapeutic delivery and disease detection throughout the gastrointestinal tract. This work will help position DSM20016 as a synthetic biology chassis for those kinds of applications. Lactobacillales have no specific model organism.Preferred species do exist, but they're usually chosen with a bias towards particular research aims. The variation within the bacterial family has led to fragmented protocols, some with iterations of modifications going back through publications. It is very difficult for people starting out to filter exactly what is and is not useful.One paper for the transformation of DSM20016 does exist, but it's not modern. Modern protocols for other Lactobacillales family members exist, but they are not DSM20016. Here we strive to provide an easy to use, centralized, modernized, complete set of protocols for DSM20016 electroporation.This protocol set offers substantial modernization over previous DSM20016 exploration protocol, and elucidates some hanging threads, as well as emphasizing parts that were previously less clear. The protocol set is also complete, and specifically for DSM20016, a strain for which other non-DSM20016 protocols are not totally compatible. One of our main goals is using microbes as inexpensive sensors and delivery systems.We're working with intestinal disease experts to use DSM20016 to sense the conditions in the gastrointestinal tract and deliver therapeutics as required.

Watch this Scientific Journal Video about Measurement of the Acid-Resistant Fluorescent Reporter Protein mCherry2 at JoVE.com

Measurement of the Acid-Resistant Fluorescent Reporter Protein mCherry2  

Medición de la proteína reportera fluorescente resistente a los ácidos mCherry2

Elija cualquier colonia de la placa de agar MRS que contenga células de L.reuteri electroporadas e inocule en una microplaca de 96 pocillos que contenga caldo MRS esterilizado por filtro por pocillo y un antibiótico de selección apropiado. Incubar aeróbicamente durante 24 horas a 37 grados centígrados sin agitar. Al día siguiente, L.reuteri se precipitará fuera de los medios en la fase estacionaria.Resuspender el cultivo mediante pipeteo. Agregue 200 microlitros de cultivo en una placa plana, transparente y de 96 pocillos inferiores. Transfiera la placa a un lector de placas y mida la densidad óptica y la fluorescencia de M cherry dos y otros reporteros relevantes.La morfología de la colonia cambia notablemente en presencia de oxígeno. En condiciones de bajo oxígeno, las colonias aparecen blancas, opacas, lisas y redondas. En condiciones parciales o con fugas, las colonias aparecen onduladas, y umbanet.Mientras que bajo los niveles de oxígeno atmosférico las colonias siempre aparecen cebo bajo, redondo y seco. En el tipo salvaje L.rueteri, el crecimiento y la expresión de la proteína reportera varían entre colonias, lo que dificulta las deducciones precisas. El curado de plásmidos y la retransformación pueden resultar en una expresión más estable, pero es una ocurrencia poco común y única que depende de fenotipos mutantes más estables que ocurren espontáneamente.

Research

JoVE Journal

Bioengineering

Measurement of the Acid-Resistant Fluorescent Reporter Protein mCherry2

Methods for Electroporation and Transformation Confirmation in Limosilactobacillus reuteri DSM20016

Lactobacillus were an incredibly large, diverse genus of bacteria comprising 261 species, several of which were commensal strains with the potential for ...

Investigación

Bioingeniería

Preparing Limosilactobacillus reuteri DSM20016 Electrocompetent Cells for Electroporation

Preparing Limosilactobacillus reuteri DSM20016 Electrocompetent Cells for Electroporation  

Preparación de Limosilactobacillus reuteri DSM20016 células electrocompetentes para electroporación

Confirmation of Plasmid Uptake via Colony PCR

Confirmación de la captación de plásmidos mediante PCR de colonias

Mini-Prep Protocol for Limosilactobacillus reuteri and Confirmation of Plasmid Presence by PCR

Mini-Prep Protocol for Limosilactobacillus reuteri and Confirmation of Plasmid Presence by PCR  

Protocolo de mini-preparación para Limosilactobacillus reuteri y confirmación de la presencia de plásmidos por PCR