All the cytotoxic extracts obtained from the fermentation broths of the bacteria isolated during the miracle project were subjected to a workflow that consisted in the following steps:
- A mass-spectrometry de-replication. All the active extracts were subjected to 4 different analysis, electrospray positive, electrospray negative, atmospheric pressure chemical ionisation (APCI) positive and APCI negative. The spectra obtained were compared to a database generated with 304 different compounds previously isolated at I. Biomar. All the samples that contained previously isolated compounds were not further studied.
The 71 active actinobacteria isolated during the Miracle at I. Biomar were subjected to this de-replication procedure and 44 extracts were discarded for containing known compounds. The compounds detected at this point were: Antimycin (in 29 extracts), Nocardamine (in 15 extracts), Geldanamycin (1 extract), Ikarugamycin (1 extract), Bafilomycin (1 extract) and different types of Steroids (3 extracts).
We received 595 strains from our partners in this project and 47 showed activity. This work is still in progress with the last strains received but so far some metabolites have been identified: fatty acids, Isocoumarins, Antimycin, Actinomycin and several Macrolides.
- The next step was the scaled-up fermentation of the active strains in which the active compound was not identified. A new mass-spectrometry de-replication was performed at this stage but it was carried out after separation of the solid and liquid phases of the fermentation broth. A different set of solvents is used too. The fermentation was performed in 2 liter flasks containing 250 ml of fermentation broth and with at least two passages of inoculum previously to inoculation of the fermentor.
Some other compounds were detected in this second step, that includes Ergosterol, several other Steroids, Genistein, Daidzein, and Antimycins.
- The third step was the fermentation at higher scales for the product isolation. 7 strains were subjected to fermentation in higher volumes (typically in multiples of 4 liter) and only two still remain in study. The rest have shown to produce known compounds all of them included in previous reports.
Additionally, there is still work with one cyanobacteria that showed good cytotoxic activity. The progress with this kind of organisms is much slower since the growth of enough quantity of cell mass for the purification of the active compound requires very long incubation periods.