Bacillus cyclic lipopeptides (CLP), part of the three main families—surfactins, iturins, and fengycins—are secondary metabolites with a unique chemical structure that includes both peptide and lipid components. Being amphiphilic compounds, CLPs exhibit antimicrobial activity in vitro, damaging the membranes of microorganisms. However, the concentrations of CLPs used in vitro are difficult to achieve in natural conditions. Therefore, in a natural environment, alternative mechanisms of antimicrobial action by CLPs are more likely, such as inducing apoptosis in fungal cells, preventing microbial adhesion to the substrate, and promoting the death of phytopathogens by stimulating plant immune responses. In addition, CLPs in low concentrations act as signaling molecules of Bacillus’s own metabolism, and when environmental conditions change, they form an adaptive response of the host bacterium. Namely, they trigger the differentiation of the bacterial population into various specialized cell types: competent cells, flagellated cells, matrix producers, and spores. In this review, we have summarized the current understanding of the antimicrobial action of Bacillus CLPs under both experimental and natural conditions. We have also shown the relationship between some regulatory pathways involved in CLP biosynthesis and bacterial cell differentiation, as well as the role of CLPs as signaling molecules that determine changes in the physiological state of Bacillus subpopulations in response to shifts in environmental conditions.

Features of the biochemical adaptations of alkaliphilic fungi to exist in extreme environments could promote the production of active antibiotic compounds with the potential to control microorganisms, causing infections associated with health care. Thirty-eight alkaliphilic and alkalitolerant Emericellopsis strains (E. alkalina, E. cf. maritima, E. cf. terricola, Emericellopsis sp.) isolated from different saline soda soils and belonging to marine, terrestrial, and soda soil ecological clades were investigated for emericellipsin A (EmiA) biosynthesis, an antifungal peptaibol previously described for Emericellopsis alkalina. The analysis of the Emericellopsis sp. strains belonging to marine and terrestrial clades from chloride soils revealed another novel form with a mass of 1032.7 Da, defined by MALDI-TOF Ms/Ms spectrometers, as the EmiA lacked a hydroxyl (dEmiA). EmiA displayed strong inhibitory effects on cell proliferation and viability of HCT 116 cells in a dose- and time-dependent manners and induced apoptosis.

A number of bacteria that colonize the human body produce toxins and effectors that cause changes in the eukaryotic cell cycle—cyclomodulins and low-molecular-weight compounds such as butyrate, lactic acid, and secondary bile acids. Cyclomodulins and metabolites are necessary for bacteria as adaptation factors—which are influenced by direct selection—to the ecological niches of the host. In the process of establishing two-way communication with the macroorganism, these compounds cause limited damage to the host, despite their ability to disrupt key processes in eukaryotic cells, which can lead to pathological changes. Possible negative consequences of cyclomodulin and metabolite actions include their potential role in carcinogenesis, in particular, with the ability to cause DNA damage, increase genome instability, and interfere with cancer-associated regulatory pathways. In this review, we aim to examine cyclomodulins and bacterial metabolites as important factors in bacterial survival and interaction with the host organism to show their heterogeneous effect on oncogenesis depending on the surrounding microenvironment, pathological conditions, and host genetic background.

We have performed a characterization of cultivated haloalkalitolerant fungi from the sediments of Big Tambukan Lake in order to assess their biodiversity and antimicrobial activity. This saline, slightly alkaline lake is known as a source of therapeutic sulfide mud used in sanatoria of the Caucasian Mineral Waters, Russia. Though data on bacteria and algae observed in this lake are available in the literature, data on fungi adapted to the conditions of the lake are lacking. The diversity of haloalkalitolerant fungi was low and represented by ascomycetes of the genera Acremonium, Alternaria, Aspergillus, Chordomyces, Emericellopsis, Fusarium, Gibellulopsis, Myriodontium, Penicillium, and Pseudeurotium. Most of the fungi were characterized by moderate alkaline resistance, and they tolerated NaCl concentrations up to 10% w/v. The analysis of the antimicrobial activity of fungi showed that 87.5% of all strains were active against Bacillus subtilis, and 39.6% were also determined to be effective against Escherichia coli. The majority of the strains were also active against Aspergillus niger and Candida albicans, about 66.7% and 62.5%, respectively. These studies indicate, for the first time, the presence of polyextremotolerant fungi in the sediments of Big Tambukan Lake, which probably reflects their involvement in the formation of therapeutic muds.

The microscopic fungi Eremothecium ashbyi and E. gossypii are known for their ability to synthetize essential oil, which has a composition similar to that of rose oil. The development of Eremothecium oil technology enables the production of rose-scented products, which are demanded by pharmaceutical, food, and perfumery industries. This study focuses on assessing the in vitro cytotoxicity of Eremothecium oil, in comparison with that of rose oil, using a combination of methods and two cell types (3T3 mouse fibroblast cell line and bone-marrow-derived mesenchymal stromal cells (BM-MSCs)). The Eremothecium oil samples possessed cytotoxic effects that varied among strains and batches. The revealed cytotoxicity level may be used to tailor the qualitative and quantitative composition of Eremothecium oil to achieve a particular quality in its end products. These results require further analysis using other cell types and assays based on measuring other cell functions.

In this study, two compounds have been isolated from the Arctic-derived fungus Penicillium chrysogenum INA 13460. Structural elucidation, performed using 2D NMR and HR-ESIMS data, has identified the compounds as stereoisomers of secalonic acids, dimeric tetrahydroxanthones. The absolute configurations of these stereoisomers have been determined through conformational NMR analysis and circular dichroism spectroscopy. The antimicrobial activity of secalonic acids D and F has been evaluated against a diverse range of microorganisms, including Gram-positive multidrug-resistant Staphylococcus aureus, Gram-negative Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, the phytopathogen Pectobacterium carotovorum VKM-B1247, and the fungi Fusarium oxysporum VKPM F 890, Aspergillus fumigatus VKM F-37, and A. niger ATCC 16404. Genomic and chemical analyses further support P. chrysogenum INA 13460 as a promising natural source for antimicrobial drug discovery and biological control applications.