Technical note: LFNS-SMOD-0.4
smod Smart Measuring Optical Device
™
Abstract
The SMODTM or Smart Measuring Optical Device, is a sensor that monitors cell growth
in situ by measuring the Optical Density
(OD600) of the culture and transfers real-time
data to a Windows PC. The device and data are managed by the SMOD Control
Software (v1.0).
In this technical note we demonstrate the
reproducibility of the data produced by the
SMOD and describe how growth curves can
be generated using the SMOD.
Authors Grand, R. S., Saraswat, M., Lifeonics Ltd.
Keywords Optical Density monitoring (OD600),
Data consistency, Growth curves, Growth rate determination, Mutant
strain analysis.
Copyright © 2016, Lifeonics Ltd.
Effortless growth curves with the SMOD
Copyright © 2015, Lifeonics Ltd.
Introduction
Different microorganisms or microorganisms
grown under different conditions have varied
growth rates. Commonly, to determine the
growth rate of a microorganism, a growth curve is generated. To do this, a cell culture
is inoculated with a low number of cells and
the Optical Density (OD600) of the culture is
measured at regular intervals over many hours. This is a time consuming task that
requires the researcher to be present for
many hours to measure the OD600. The Smart Measuring Optical Device (SMODTM)
provides a long awaited solution to this task
by measuring the OD600 of a culture in situ,
in real-time and transmitting the data wirelessly to a PC, automatically creating a
growth curve and freeing up researchers
time.
How the SMOD he lps to
generate growth curves? Many parameters alter the growth rate of
microorganisms such as growth medium
(Figure 3), temperature and mutations (Figure 4). For many procedures the growth
rate of microorganisms needs to be
determined. For example, to be able to estimate how long it will take for a culture to
reach a specific OD600 or to compare the
g r o w t h r a t e b e t w e e n d i f f e r e n t
microorganism strains. The conventional way to produce a growth curve requires a
researcher to take samples of a cell culture
at regular intervals over many hours and measure the OD600 in a bench top
spectrophotometer. This has a number of
issues. First, monitoring multiple cultures at
once is a time consuming process. Second, once cultures reach high ODs they need to
be diluted to be accurately measured in a
bench top spectrophotometer. Third, as a
result of the first two issues, the culture cannot be monitored at short time intervals
(e.g. every 10 minutes) because the
researcher would have to continually take measurements. This would frequently
interrupt the culturing process (e.g. shaking
speed and cause fluctuations in incubation
temperature) because the incubator is opened every time a sample(s) is taken,
resulting in high variability between
measurements. The use of the SMOD elevates these issues by enabling the OD600
of many cultures to be monitored in parallel
and to high OD600 without the need for
culture dilution. Furthermore, because the measurements are taken in situ, the culturing
process is not interrupted and the
measurements can be taken at shorter time intervals (as frequent as every 10 minutes).
As a result the SMOD delivers highly
reproducible data (Figures 1 - 2), generates
clean growth curves and enables the precise determination of growth rate (Figures 1 - 4).
Conclusion
D e t e r m i n i n g t h e g r o w t h r a t e o f microorganisms is a common technique
used to estimate how long organisms take
to reach a particular growth phase or to
compare the growth of different organisms. This is a time consuming and laborious task
that no one enjoys. With the SMOD - the lab
is in the sample - enabling real-time, continuous monitoring of culture growth
without interrupting the culturing process.
This provides an effortless method to
determine the growth rate of any microorganism grown in a suspension
culture.
Copyright © 2016, Lifeonics Ltd.
Figure 2. Optical density measurements taken by SMODs in separate Yeast cultures are highly reproducible. The growth of three separate Yeast (Schizosaccharomyces pombe) cell cultures in YES medium was monitored with the SMOD over-night. Cells were grown at a constant temperature (300C) with agitation (200rpm) and the average Optical Density (OD600) measurements of the three SMODs is graphed with the standard deviation (Black). Also shown is the average temperature of the cultures as measured by the SMOD with the standard deviation (Blue).
Figure 1. Optical density measurements taken by two SMODs in the same Escherichia coli culture are highly reproducible. The growth of E. coli cells in LB medium was monitored by two SMODs in the same culture to determine the reproducibility of the Optical Density measurements between SMODs. Cells were grown at a constant temperature (370C) with agitation (200rpm) and the average Optical Density (OD600) measured by the two SMODs is graphed with the standard deviation (Black). Also shown is the average temperature of the cultures as measured by the SMOD with the standard deviation (Blue).
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Copyright © 2016, Lifeonics Ltd.
Figure 4. The SMOD can be used to quantifying the difference in growth rate between different mutant strains. Two Wild-type (Black) and Mutant (Red) Yeast (Schizosaccharomyces pombe) cell cultures were grown in YES medium and the OD600 was monitored with the SMOD. Cells were grown at a constant temperature (300C) with agitation (200rpm) and the average Optical Density (OD600) measurements of two replicates is graphed with the the standard deviation (Black and Red). Also shown is the average temperature of the cultures as measured by the SMOD with the standard deviation (Blue).
Figure 3. The SMOD can be used to determine the difference in growth rate when cell are grown in different medium. Escherichia coli cells were grown in LB medium without (Black) and with (Red) MgSO4 and the OD600 was monitored with the SMOD. Cells were grown at a constant temperature (370C) with agitation (200rpm) and the Optical Density (OD600) measurements are plotted (Black and Red). Also shown are the temperatures of the cultures as measured by the SMOD (light and dark Blue).
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