How are the euglena samples, collected and sent by people from various places, analyzed in the laboratory of the Microalgal Production Control Technology Research Team?

The procedure is divided into four main steps:

1. Cultivating the samples sent to us,
2. Isolating them using a cell sorter,
3. Reading the DNA sequence of each cultivated euglena candidate, and
4. Comparing the read DNA sequences. In this article, we will introduce the cultivation of the samples sent to us.

The first hurdle: Can it be cultivated? Our research team is on the hunt for euglena that might change the world. For industrial use, it's ideal that the new euglena can be cultivated in large quantities. For instance, Figure 1 shows a facility (located in Ishigaki Island) cultivating E. gracilis, a euglena already in industrial use, with a diameter of 30m (Reference 1). It's essential that they can proliferate until the facility is full.

Outdoor Cultivation of Euglena

Figure 1: E. gracilis cultivation facility (Cited from Reference 1)

As can be inferred from Figure 1, for cost-effectiveness and to utilize sunlight, it's best to cultivate euglena outdoors in large quantities. However, outdoors, there's a high likelihood of contamination by unwanted microorganisms, as shown in Figure 2.

Figure 2: Example of fungal contamination (Modified from Reference 1)

To address this issue, euglena is cultivated under conditions where it can proliferate, but other organisms cannot. Specifically, they are cultivated in acidic media (the liquid used for cultivation). Fungi and lactic acid bacteria thrive in pH 5-6 media, while prokaryotes like E. coli and actinomycetes prefer pH 7-8. In contrast, euglena can proliferate even in highly acidic media with a pH of 3.5 (Reference 1).

The samples sent to us are cultivated in acidic media. As they grow, a small portion is transferred to a new medium for further cultivation. This process is repeated. Those euglena candidates that survive even under these stringent conditions have passed the first hurdle.

In the next step (2), the cultivated "euglena candidates" are isolated using a device called a cell sorter.

References

1. Suzuki K. (2017) Large-Scale Cultivation of Euglena. In: Schwartzbach S., Shigeoka S. (eds) Euglena: Biochemistry, Cell and Molecular Biology. Advances in Experimental Medicine and Biology, vol 979. Springer, Cham