Technical note: LFNS-SMOD-0.6

smod Smart Measuring Optical Device

™  

Abstract

The SMODTM or Smart Measuring Optical Device, is a sensor that monitors cell growth

in situ (OD600) and transfers data in real-time

to a Windows PC. The device and data are

managed by SMOD Control Software (v1.0).

In this technical note we demonstrate how

the SMOD can be used to monitor cell growth over a long time period, over 30

hours.

Authors Grand, R. S., Seymour, C., Lifeonics Ltd.

Keywords Optical Density monitoring (OD600),

Growth curves, Slow growth strains, Long time monitoring of OD600 and

temperature.

Copyright © 2016, Lifeonics Ltd.

Monitoring slow growing cultures with the SMOD

Introduction

Commonly grown microorganisms proliferate rapidly and, therefore, creating growth curves or

obtaining a desired growth stage is achieved within 16h – see Technical Notes LFNS-SMOD-0.2

and LFNS-SMOD-0.4 for setting up an experiment and growth curve analysis with the SMOD. However, there are microorganisms and mutant strains that grow much slower, so the Optical

Density (OD600) needs to be monitored over a longer time (>16h). The Smart Measuring Optical

Device (SMOD) can be used to non-invasively monitor slow growing suspension cell cultures

using the - slow growth - monitoring protocol outlined here.

  How to use the SMOD to monitor slow growing microorganisms

Set up an experiment as normal - see Technical Note LFNS-SMOD-0.2 - to monitor the culture

growth for the first ~16 hours. Then to extend the time over which the OD600 of the culture can be monitored there are two methods, both of which require a second, fully changed SMOD, to

be added to the culture after ~14 hours.

Copyright © 2016, Lifeonics Ltd.

Copyright © 2016, Lifeonics Ltd.

Method one:

After ~14 hours, before the battery of the

first SMOD runs out, set up an experiment

with a second SMOD (Figure 1):

1 Start a New Experiment, select a

SMOD from the dropdown menu and identify it using the Glow button

2’ Remove the SMOD from the

charger and place it into a flask containing the same medium that was used to

starting the culture

3’ Place the flask into the incubator to

Equilibrate the temperature (~30min)

4’ Remove the flask from the incubator and Take the Blank

5’ Remove the SMOD from the flask and add it to the flask containing the

already growing culture

6 Place the flask back into the incubator and Start the experiment

7 Once the experiment has finished,

download the data and line up the OD values measured by the second SMOD

with those from the first SMOD using the

time stamp, then graph the data (Figure 2).

Figure 1. Diagram outlining the use of the SMOD to monitor cell culture growth over long time periods with Method One.

Copyright © 2016, Lifeonics Ltd.

Method two:

After ~14 hours, before the battery of the

first SMOD runs out, set up an experiment

with a second SMOD (Figure 3):

1 Start a New Experiment, select a

SMOD from the dropdown menu and identify it using the Glow button

2’ Remove the SMOD from the

charger and place it into the culture flask containing the already growing culture

3’ Place the flask back into the incubator to Equilibrate the tempearture

(~30min)

4’ Remove the flask from the incubator, Take the Blank on the already

growing culutre

5’ Place the flask back into the

incubator and Start the experiment

6 Once the experiment has finished,

download the data and line up the values

read by the second SMOD with those from

the first SMOD using the time stamp. Subtract the first OD reading taken by the

second SMOD from the OD measured by

the First SMOD at the same time. Then add this value to every OD reading taken

by the second SMOD to determine the

actual OD of the culture. Graph the data

(Figure 4).

Figure 3. Diagram outlining the use of the SMOD to monitor cell culture growth over long time periods with Method Two.

Copyright © 2016, Lifeonics Ltd.

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Figure 2. Using the SMOD to monitor cell culture growth over more then 30 hours with Method One. To demonstrate the use of the SMOD to monitor cultures over a long time period an Escherichia coli culture was monitored with two SMODs using Method One. The growth of E. coli cells in LB medium was monitored from the start of the culture by the first SMOD for 18h. Then a second SMOD was added to the culture during exponential phase growth, taking measurements over 16h. The Optical Density (OD600) and temperature measurements take by the two SMODs were highly reproducible and gave a total monitoring time of 34 hours. Cells were grown at constant temperature (370C) with agitation (200rpm) and the Optical Density (OD600) and temperature measured by the two SMODs is graphed.

Figure 4. Using the SMOD to monitor cell culture growth over more then 30 hours with Method Two. To demonstrate the use of the SMOD to monitor cultures over a long time period an Escherichia coli culture was monitored with two SMODs using Method Two. The growth of E. coli cells in LB medium was monitored from the start of the culture by the first SMOD for 17h. Then a second SMOD was added to the culture during exponential phase growth, taking measurements over 17h. The Optical Density (OD600) and temperature measurements take by the two SMODs were highly reproducible and gave a total monitoring time of 34 hours. Cells were grown at a constant temperature (370C) with agitation (200rpm) and the Optical Density (OD600) and temperature measured by the two SMODs is graphed.

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