Monitoring Yeast Cell Growth in the Presence of Ethanol

The yeast Saccharomyces cerevisiae is a single celled organism used in numerous tasks. The fast growing and unicellular nature of the yeast along with its asexual reproduction capabilities make it an ideal model to study the biology and genetics of eukaryotic cells. Besides its importance in scientific research yeast play an essential role in the baking of bread, the fermentation of alcohol for consumption and for biofuels.

Many of the assays employed with yeast involve variant or mutant strains the exhibit differences in growth under selective conditions. For example mutations that cannot grow without certain nutrients can be identified. Ethanol resistance to growth inhibition is another important parameter for the production of alcohol biofuel or the fermentation of beer and wine. Because individual yeast clones can be grown, one can identify unique strains that exhibit the desired growth characteristics in microplate.

Cell suspensions (bacterial or eukaryotic) result in light scatter when a light beam is passed through them. Using a spectrophotometer or a microplate reader this light scatter is detected as an increase in absorbance. While not strictly obeying Beer’s law, this relationship can still be exploited to monitor cell growth using absorbance. We have used the Synergy H1 Multi-Mode Microplate reader to monitor the growth of beer strains of yeast under different concentrations of ethanol.

Figure 1. Effect of Ethanol Concentration on the Growth of Strain 2000 Budvar lager beer yeast.

By following the growth of yeast cells in suspension, the effect of environmental conditions such as ethanol concentration can be monitored (Figure 1). The log-phase of yeast cell growth is linear with respect to the change of absorbance (cell number) per unit of time for a given ethanol concentration. As such, changes in the slope as a result of ethanol concentration can be plotted for individual strains and compared (Figure 2).

Figure 2. Effect of ethanol on log-phase growth rate.

These data demonstrate the utility of the Synergy H1 to monitor kinetically yeast cell growth in the presence of ethanol. Yeast cultures require constant temperature along with adequate agitation in order for consistent repeatable results. Besides providing adequate mixing of the cellular nutrient suspension for cellular growth, maintenance of a uniform suspension allows for accurate light scatter measurements. The Synergy H1 has a number of different shaking features including linear, orbital and double or figure eight shaking modes. Each mode can also be adjusted for speed and amplitude, providing a number of different mixing options for different materials.

Do you measure yeast cells in suspension? Do you have a need for a microplate reader?


By Paul Held,Ph.D, Principal Scientist, BioTek Instruments, Inc.

First Stem Cell Clinical Trial for Stroke Patients

Most of us have someone in their families or know of a family where one of the members has suffered from a stroke. When it doesn’t kill (stroke is the third largest cause of death in the developed world) it often disables the victim. Strokes usually occur on only one side of the brain, so decreased motor control usually develops on only one side of the body. In fact, one side of the body may be paralyzed (hemiplegia), or muscles on the affected side may be weakened (hemiparesis). Memory loss is another common symptom that many patients experience after a stroke. Further, a patient's attention span tends to be shorter and may display as dementia. According to the National Center on Physical Activity and Disability (NCPAD), in 2007, four million stroke survivors were living in the United States, and more than 730,000 Americans experience a stroke each year. It is the leading cause of disability in the developed world.

Thus there is heartening news from the world of stem cell therapy, which holds promise for regenerative medicine in general and in this case, the reversal of stroke disabilities. Today, ReNeuron Group plc announced that the first patient has been treated with the Company’s ReN001 stem cell therapy for stroke in a clinical trial. The PISCES study (Pilot Investigation of Stem Cells in Stroke) is the world’s first fully regulated clinical trial of a neural stem cell therapy for disabled stroke patients. The Phase 1 PISCES trial is designed primarily to test the safety profile of ReN001 in ischaemic stroke patients at a range of cell doses, but a number of efficacy measures will also be evaluated over the course of the two year trial. Subject to satisfactory safety data, the Company intends to pursue an accelerated clinical development pathway with ReN001, focusing on particular stroke patient groups who are expected to most benefit from the therapy.

Planet xMAP Travels to Vienna

Luminex’s Planet xMAP Europe 2010 was held October 20-21 at the Hofburg Congress Center in Vienna, Austria with over 500 scientists in attendance to see the latest in xMAP technology from Luminex and their licensing reagent partners. A major focus of the meeting was the new MAGPIX reader for 96-well magnetic bead assays (50 plex maximum) which expands Luminex’s reader portfolio creating a lower end, value priced solution for assays developed on the xMAP platform. The well known Luminex 100/200 (96-well plates, 100/200 plex), Luminex’s flagship product, will continue to be sold along with the FlexMAP 3D (96- and 384-well, 500 plex) for higher throughput applications. The Hofburg was bustling in activity with two keynote speakers, 7 satellite sessions and 35 customers from around the world presenting their research utilizing xMAP technology. Professor Sabine Bahn, MD PhD MRCPsych of the Cambridge Center for Neuropsychiatric Research presented her work on “Disease Biomarkers in First-Onset Schizophrenia” while Carlo Croce, MD of the Centre Alexis Vautrin spoke about “Causes and Consequences of microRNA Dysregulation in Cancer”. Satellite sessions included Pathogen Detection, Immunology Monitoring, Human Genetics, Newborn Screening, Protein Research, Genomic Research and Respiratory Viruses.




Located in the center of Vienna, the Hofburg Imperial Palace was an amazing location for this year’s meeting. Back in the days of the Habsburg dynasty, rulers of the Austro-Hungarian empire, the Hofburg served as the winter residence to a line of mighty emperors. Built between the 13th and 19th centuries, the large complex currently houses a vast number of cultural and congress facilities including the official residence of the President of Austria.

19 exhibiting companies showcased their xMAP focused products to existing and new users alike. BioTek Instruments was a silver sponsor at this year’s meeting and featured the ELx50 Strip Washer and the ELx405 Washer as two different levels of xMAP sample processing automation. Both instruments were available for customer demonstrations together with their available modules for biomagnetic separation and vacuum filtration. Although users realize they can wash their samples with manual magnet stations and vacuum manifolds, it is evident that those with experience appreciate the added value of unattended operation provided by automated microplate washers. BioTek also presented a scientific poster titled "Automated Processing of Bead-based Cytokine Multiplex Assays using Multiple Washer Platforms" highlighting ELx50 vacuum and ELx50/ELx405 magnetic bead washing compared to manual processes using Cytokine Panels from Bio-Rad and Life Technologies.



By Jason Greene, Product Manager