Role of plant metabolites on the regulation of bioactive metabolite production in cyanobacteria - Omnic's approach (CNPreg)

Cyanobacteria are a large group of photoautotrophic prokaryotes, ubiquitous in nature and found to have symbiotic relationships with a broad range of eukaryotic hosts including plants. These interactions can occur in different ways, both beneficial and harmful. A beneficial symbiosis have been demonstrated with rice with long-term stable endophytic association. Some plants enhance their chances of infection by producing chemical signals/ chemo-attractants to stimulate hormogonia formation and direct it into the plant tissue. The chemical communication between the host and the cyanobiont have been also speculated, where the role of flavonoids, lectins, and other small molecules were reported. A lot of research is done concerning the metabolic change in plants during symbiosis or when treated with cyanobacteria or growth media thereof. However, the reverse way holds a research gap: The influence of plant secondary metabolites on regulation of cyanobacterial metabolites production.

Cyanobacteria are prolific producer of a large array of natural products. Approximately 26% of the total known metabolites produced by filamentous cyanobacteria. From a biotechnology perspective, these compounds have been widely studied for a broad spectrum of biological activities comprising anti-inflammatory, anticancer, immune-modulating activities and with significant biocidal activity against important agricultural insect-pests. Among many, members of genus Nostoc are one of the most widely studied genera of cyanobacteria or found to have symbiotic association. Regrettably, inter-kingdom interactions among the biofilm-forming cyanobacteria and plants have been neglected which might underlie metabolite production.

We hypothesized that the ability of cyanobacteria to produce certain secondary metabolites, is triggered or shifted by secondary plant metabolites. Secondary plant metabolites exert a wide range of effects on the plant itself and on other living organisms. Over 50,000 secondary plant metabolites have been discovered from the plant kingdom exhibiting broad range of bioactivity. They can be divided into subclasses such as the alkaloids, saponins, essential oils, flavonoids and many more. In contrast to plant produced metabolites, very limited data is available on metabolites produced by cyanobacteria for their chemical defense. It has also been hypothesized that the production of defending metabolites is controlled by the presence of competitors, bacteria, light intensity, temperature, nutrient levels, and pH.

In this project the plant extracts will be used as plant based pseudo-competitor, which shift the spectra of metabolites of cyanobacteria. The established consortium, with the expertise of the principal investigator’s (PI), Dr. Kumar Saurav team in chemical isolation, purification, and genome mining together with Dr. Corinna Urmann - knowledge in analysis, extraction and synthesis of plant-based natural products and enzyme and cell based bioactivity testing will enable the discovery of novel and less known cyanobacterial metabolites and will allow in-depth study on the regulation of its production. To achieve the aims set in the project, an innovative interdisciplinary approach is used that combines scientific fields including basic microbiology, analytical chemistry (omnics), and bioactivity testing (anti-virulence, protective and regenerative activity).