Thermophiles are fascinating microorganisms that include fungi, algae, cyanobacteria, and protozoa. They grow best at temperatures higher than 45°C and hyperthermophiles at over 90°C. Thermophiles are limited to bacteria and archaea and inhabit a wide range of environments and niches from hydrothermal vents, hot water tanks, compost, volcanic sites and coal refuse to name a few.

They range from spore forming bacteria such as Bacillus, Clostridia and Moorella species to photosynthetic bacteria including cyanobacteria and green- and purple-suphur microbes like Chromatium.

There are also sulphur oxidisers such as Thiobacillus, sulphate reducers like Desulfovibrio and acidophiles such as Sulfolobus, Metallosphaera and there is Aciduliprofundum boonei which is found in hydrothermal vents featured on TV documentary programmes.

Their physiology and extreme biochemistry that enables them to tolerate and thrive in such extreme environments is fascinating.

Genomic analysis has been enabled by high-throughput sequencing to analyse these environments and their microbial composition. But only by studying their physiology and growth dynamics can we elucidate their fascinating potential.

Only by studying their physiology and growth dynamics can we elucidate their fascinating potential.

The molecular mechanisms that enable them to metabolise, grow and tolerate such extreme conditions can help unlock advanced industrial, biochemical and chemical treatments and even in the mining and processing of metals. We only need to remember the taq polymerase enzyme used in PCR reactions for example !

Their potential catalytic robustness in extreme conditions is attractive for industrial applications. Angelo Fontana et al. in Progress in Biotechnology, as far back as 1998 identified that “thermophilic enzymes are usually poor catalysts at room temperature”. Counter-intuitively they found that thermostable enzymes are not rigid molecules at room temperature and this molecular elasticity is a function of catalytic efficiency. There is an “inverse correlation between enzyme activity and thermostability has been demonstrated in several cases” due to mobility and catalytic potency.

Harnessing and unlocking thermophilic molecular mechanisms can help create recombinant mesophilic hosts for producing those thermophilic enzymes for example. Since thermophiles survive on minerals, metals and gases their metabolic processes and enzymes hold promise for industrial, biochemical, biotechnological and other applications.

The key to unlocking the benefits of thermophiles and their amazing biochemistry is identifying microbes, characterising them and understanding their relevance.

Having the tools to allow us to isolate and grow these microbial species and communities is key to the beneficial exploitation of microbes.

Few tools are available for identifying and characterising microbial physiology and measuring their growth and responses to environmental changes and stimuli. This is especially the case with thermophiles, since their heat loving preferences are not easily compatible with electronic devices !

Obtaining data on growth dynamics allows the characterisation of thermophilic physiology and the optimisation of biotechnological applications.

There are not many devices capable of measuring anaerobic and thermophilic growth rates over extended periods with high-resolution data and non-disruptive sampling techniques reproducibly and repeatably.

Growth measurement devices need to provide comparable measurements, reproducibly, obtain high-resolution data and permit standardised methods across devices. Data must be obtained with a high enough resolution to allow for mathematical modelling and statistical analysis.

Data must also be obtained over long periods of time for slow growing cultures. Devices need to support different conditions over the growth period and record physiologically significant events at consistently high temperatures. Overall, these are very demanding criteria and few devices have these capabilities.

Existing laboratory equipment can be used to measure microbial growth, such as spectrophotometers and plate readers, but they have important limitations that make long-term measurement difficult if not impossible under certain conditions.

There are however, dedicated and innovative devices from Humane Technologies that measure microbial growth for many days at a time. We believe our devices that measure continuous thermophilic growth at up to 85˚C are a world first !

Studying thermophilic physiology, especially of thermophilic anaerobes, is very challenging experimentally.

Using devices capable of measuring thermophilic growth rates over extended periods with high resolution at temperature extremes, that challenge electrical equipment to their limits, is key to studying their physiology.

MicrobeMeters are programmable photometers for continuous measurement of thermophilic microbial growth at up to 85˚C.

For more information please visit our products page here.

MicrobeMeters are wireless automated OD600 photometers for measuring microbial cell growth, for anaerobes, aerobes and thermophiles.


MicrobeMeters have significant advantages over some spectrophotometers:

Improved productivity: High-resolution real-time data directly to your computer from your incubator, continuously for many days.

Continuous turbidity data: No out-of-hours lab visits, lower risk of contamination, no interruption of your experimental conditions. Continuous growth data from your incubator at up to 85˚C !

Programmable: Programmable data capture intervals for both fast and very slow cell cultures. Software included.

Publication-Ready Data: Enables accurate analysis and modelling of microbial cell growth dynamics with publication-ready data.

Advantages over some Spectrophotometers: MicrobeMeter has 3 key advantages over spectrophotometers:

1. MicrobeMeter has lower variability compared with some spectrophotometers,

2. as accurate as some, and

3. is less sensitive to light scattering by different cell types.


Evolution has provided rich microbial diversity over millennia.

Understanding thermophilic growth and dynamics is key to studying the genomics, biochemistry and physiology of thermophiles and reveal the benefits they could offer.

Only then will it be possible to harvest this microbial diversity and exploit them for new biotechnological, medical, agricultural and other applications.

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