ndary metabolites. Anabaenopeptin was absent in Nostoc sp. ErbB3/HER3 MedChemExpress strain KVJ2 biomass obtained beneath traditional cultivation. High-density cultivation of this strain revealed the presence of 3 novel anabaenopeptins (KVJ827, KVJ841, and KVJ811). The raise on the content of those APs in the strain KVJ2 is attributed to a greater quantity of transcriptions amongst the cells. Inside the traditional cultivation, the distribution on the aptA transcripts (an NRPS gene related to AP production) was restricted only to a cell at (pre-)akinete state when in high-cell density culture, this transcript was widely distributed amongst the vegetative cells [21]. The interaction involving unique chemotypes of cyanobacteria in a water physique can provoke considerable alterations in their secondary metabolites profile. Consequently, variations are observed between laboratory culture and organic environments. In co-culture with M. CYP26 Gene ID aeruginosa PCC 7806, the non-microcystin-producing strain M. aeruginosa PCC 9432 enhanced its bioactive peptide content material, which includes Ferintoic acids A and B [90]. These findings suggest the release of diffusible signals by cyanobacteria together with the capacity of regulating the production of APs. The chemical nature of such metabolites was not determined in this study. Even so, specific oligopeptides can fill the signaling function given that they may be sometimes identified in the extracellular compartment, acting as infochemicals. Also to peptides, cyanobacterial exudate has also some nutrients, which influence the production of specific toxins and can be, consequently, accountable for the boost of Ferintoic acids A and B in M. aeruginosa PCC 9432 [100]. Within a later study, the supplementation from the culture medium of a P. agardhii with two oligopeptides extracts from samples of P. agardhii as the predominant cyanobacterial species had distinct effects around the synthesis on the peptides of this strain. Each extracts showed a good influence on biomass accumulation and chlorophyll-a production, becoming attributed to these nutrients and oligopeptides now present. The higher nutritional content in the extracts is linked with the capacity of cyanobacterial in fixing nitrogen and generating vitamins, phytohormones, and polysaccharides. Three out of 4 anabaenopeptins maintained constant (m/z 851, 844, and 837) while the variant with m/z 828 was substituted by other with m/z 923. One of the extracts increased the anabaenopeptin content material of variants m/z 844, 851, and 837 when the other diminished the quantity of those last two [101]. The opposite responses to these extracts can be assigned for the content differences observed between them. The extract accountable for decreasing the APs expression exhibits a superior concentration of nitrate and phosphate, which, as was previously pointed out features a unfavorable impact around the production of anabaenopeptin [27]. Additionally to interaction with other cyanobacteria, these microorganisms are capable to establish symbiotic associations with invertebrates, which include corals, mollusks, and sponges. Both organisms may be benefited in the course of this consortium by way of secondary metabolite production, for example [102]. Sponges host an massive quantity of microorganisms belonging to diverse phyla, exactly where cyanobacteria are mainly represented by genera Aphanocapsa, Synechocystis, Phormidium, and Oscillatoria [103]. These photosynthetic microorganisms can occupy either extra- or intracellular spaces, aiding the host within the manage of the redox