The microbial conversion of agro-industrial oil wastes into biosurfactants shows promise as a biomass refinery approach. In this study, Bacillus subtilis #309 was applied to produce surfactin using rapeseed and sunflower cakes, the most common oil processing side products in Europe. Studies of the chemical composition of the substrates were performed, to determine the feasibility of oil cakes for surfactin production. Initially, screening of proteolytic and lipolytic activity was performed to establish the capability of B. subtilis #309 for substrate utilization and hence effective surfactin production. B. subtilis #309 showed both proteolytic and lipolytic activity. The process of surfactin production was carefully analyzed by measurement of the surfactin concentration, pH, surface tension (ST) and emulsification index (E₂₄). The maximal surfactin concentration in the sunflower and rapeseed cake medium reached 1.19 ± 0.03 and 1.45 ± 0.09 g/L, respectively. At the same time, a progressive decrease in the surface tension and increase in emulsification activity were observed. The results confirmed the occurrence of various surfactin homologues, while the surfactin C₁₅ was the dominant one. Finally, the analysis of surfactin biological function exhibited antioxidant activity and significant angiotensin-converting enzyme (ACE)-inhibitory activity. The half-maximal inhibitory concentration (IC₅₀) value for ACE inhibition was found to be 0.62 mg/mL for surfactin. Molecular docking of the surfactin molecule to the ACE domains confirmed its inhibitory activity against ACE. Several interactions, such as hydrophobic terms, hydrogen bonds and van der Waals interactions, were involved in the complex stabilization. To the best of our knowledge, this is the first report describing the effect of a lipopeptide biosurfactant, surfactin, produced by B. subtilis for multifunctional properties in vitro, namely the ACE-inhibitory activity and the antioxidant properties, using different assays, such as 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). Thus, the ACE-inhibitory lipopeptide biosurfactant shows promise to be used as a natural antihypertensive agent.

Stearin-derived waste glycerol as an economic substrate for biosurfactant production usingPseudomonas antarcticaisolated from the Arctic Archipelago of Svalbard.

Brewers' spent grain was used as a substrate to obtain protein hydrolysates with antioxidant activity. Hydrolysis was conducted in the culture using proteolytic bacteria. Hydrolysis was controlled by measurement of α-amino group concentration and with the aid of size exclusion chromatography. For each culture the degree of hydrolysis was calculated. The most efficient protein hydrolysis was observed in the cultures of Bacillus cereus (43.06%) and Bacillus lentus (41.81%). In addition, gelatin zymography was performed in order to detect bacterial proteases and their activity. The profile of secreted enzymes was heterogeneous, while the greatest variety was observed for Bacillus polymyxa. Brewers' spent grain protein hydrolysates exhibited high antioxidant activity. Bacillus subtilis and Bacillus cereus post-cultured media displayed the highest activity, respectively 1291.97 and 1621.31 μM TEAC per g for ABTS, 188.89 and 160.93 μM TEAC per g for DPPH, and 248.81 and 284.08 μM TEAC per g for the FRAP method.

Proteolytic enzymes are commercially valuable and have multiple applications in various industrial sectors. The most studied proteolytic enzymes produced by Yarrowia lipolytica, extracellular alkaline protease (Aep) and extracellular acid protease (Axp), were shown to be good candidates for different biotechnological applications. In this study, we performed a comprehensive analysis of the alkaline proteolytic enzymes of Yarrowia clade species, including phylogenetic studies, synteny analysis, and protease production and application. Using a combination of comparative genomics approaches based on sequence similarity, synteny conservation, and phylogeny, we reconstructed the evolutionary scenario of the XPR2 gene for species of the Yarrowia clade. Furthermore, except for the proteolytic activity of the analyzed Yarrowia clade strains, the brewers’ spent grain (BSG) was used as a substrate to obtain protein hydrolysates with antioxidant activity. For each culture, the degree of hydrolysis was calculated. The most efficient protein hydrolysis was observed in the cultures of Y. lipolytica, Y. galli, and Y. alimentaria. In contrast, the best results obtained using the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) method were observed for the culture medium after the growth of Y. divulgata, Y. galli, and Y. lipolytica on BSG.

The functioning of neuronal networks critically depends on the coordinated interaction between excitation and inhibition. The properties of glutamatergic and GABAergic synapses are finely tuned by network activity, and the heterosynaptic nature of inhibitory plasticity further emphasizes their functional coupling. Although the dependence of glutamatergic plasticity on protein synthesis is well established, the role of translation in inhibitory plasticity remains unclear. Herein, we investigated how protein synthesis supports the concurrent plasticity at inhibitory and excitatory inputs onto CA1 pyramidal neurons. To this end, we applied a high-frequency stimulation protocol of CA3-CA1 input combined with prolonged postsynaptic depolarization of principal cells. This induced both glutamatergic long-term potentiation (LTP) and inhibitory LTP (iLTP) at synapses formed by somatostatin-expressing interneurons onto pyramidal neurons. Although LTP was observed in slices from both juvenile (≤45 days) and adult (>45 days) mice, iLTP was only present in the adult group, revealing an unusual developmental profile. Moreover, in adult animals, excitatory LTP was required for the induction of iLTP but did not determine its magnitude. We found that bath application of translation inhibitor cycloheximide (CHX) strongly attenuated LTP and converted co-occurring iLTP into iLTD. However, when CHX was restricted to the recorded postsynaptic neuron, the initial phase of iLTP proceeded normally, but GABAergic currents gradually returned to baseline levels, indicating intact induction but impaired maintenance. In contrast, postsynaptic CHX left excitatory LTP unaffected. Together, these findings identify two distinct translational mechanisms: a postsynaptic one necessary for strengthening inhibition and a non-postsynaptic process required to potentiate excitation.