Rhamnolipids are extensively studied biosurfactants due to their potential in many industrial applications, eco-friendly production and properties. However, their availability for broader application is severely limited by their production costs, therefore the optimization of efficacy of their cultivation gains significance as well as the information regarding the physio-chemical properties of rhamnolipids resulting from various cultivation strategies. In this work, the bioprocess design focused on optimization of the rhamnolipid yield of Pseudomonas aeruginosa DBM 3774 utilizing the response surface methodology (RSM). Six carbon sources were investigated for their effect on the rhamnolipid production. The RSM prediction improved the total rhamnolipid yield from 2.2 to 13.5 g/L and the rhamnolipid productivity from 11.6 to 45.3 mg/L/h. A significant effect of the carbon source type, concentration and the C/N ratio on the composition of the rhamnolipid congeners has been demonstrated for cultivation of P. aeruginosa DBM 3774 in batch cultivation. Especially, changes in presence of saturated fatty acid in the rhamnolipid congeners, ranging from 18.8% of unsaturated fatty acids (carbon source glycerol; 40 g/L) to 0% (sodium citrate 20 g/L) were observed. This demonstrates possibilities of model based systems as basis in cultivation of industrially important compounds like biosurfactants rhamnolipids and the importance of detailed study of interconnection between cultivation conditions and rhamnolipid mixture composition and properties.

The ever-growing range of possible applications of nanoparticles requires their mass production. However, there are problems resulting from the prevalent methods of nanoparticle production; physico-chemical routes of nanoparticle synthesis are not very environmentally friendly nor cost-effective. Due to this, the scientific community started exploring new methods of nanoparticle assembly with the aid of biological agents. In this study, ethanolic Vitis vinifera cane extract combined with silver nitrate was used to produce silver nanoparticles. These were subsequently characterized using UV-visible (UV-Vis) spectrometry, transmission electron microscopy, and dynamic light-scattering analysis. The antimicrobial activity of produced nanoparticles was tested against the planktonic cells of five strains of Gram-negative bacterium Pseudomonas aeruginosa (PAO1, ATCC 10145, ATCC 15442, DBM 3081, and DBM 3777). After that, bactericidal activity was assessed using solid medium cultivation. In the end, nanoparticles’ inhibitory effect on adhering cells was analyzed by measuring changes in metabolic activity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay-MTT). Our results confirmed that ethanolic Vitis vinifera cane extract is capable of mediating silver nanoparticle production; synthesis was conducted using 10% of extract and 1 mM of silver nitrate. The silver nanoparticles’ Z-average was 68.2 d nm, and their zeta potential was –30.4 mV. These silver nanoparticles effectively inhibited planktonic cells of all P. aeruginosa strains in concentrations less than 5% v/v and inhibited biofilm formation in concentrations less than 6% v/v. Moreover, minimum bactericidal concentration was observed to be in the range of 10–16% v/v. According to the results in this study, the use of wine agriculture waste is an ecological and economical method for the production of silver nanoparticles exhibiting significant antimicrobial properties.

The use of antibiotics or antifungals to control infections caused by pathogenic microorganisms is currently insufficiently effective because of their emerging resistance. Thanks to the ability of microorganisms to form a biofilm and thus increase their resistance to administered drugs even more, modern medicine faces the task of finding novel substances to combat infections caused by them. In this regard, the effects of essential oils or plant extracts are often studied. Among the relatively neglected plants is Boswellia serrata, which has a high content of biologically active boswellic acids. In this study, we focused on one of the most common nosocomial infections, which are caused by Candida species. The most common representative is C. albicans, although the number of infections caused by non-albicans species has recently been increasing. We focused on the antifungal activity of Boswellia serrata extract Bioswellix against planktonic and adhering cells of Candida albicans, Candida parapsilosis and Candida krusei. The antifungal activity against adhering cells was further explored by determining the metabolic activity of cells (MTT) and determining the total amount of biofilm using crystal violet. Boswellic acid-containing plant extract was shown to suppress the growth of a suspension population of all tested Candida species. Boswellia serrata extract Bioswellix was most effective in inhibiting C. albicans biofilm formation.

The utilization of waste materials for the synthesis of nanoparticles has gained significant attention due to its potential for waste valorization and contribution to circular economy. In this study, bimetallic nanoparticles were produced using extracts derived from Cannabis sativa and Vitis vinifera waste, focusing on their green synthesis and antimicrobial activity against Gram-negative bacteria, specifically several strains of Pseudomonas aeruginosa. The Vitis vinifera canes and post-extraction waste from Cannabis sativa were processed using an ethanol extraction method. The extract was then mixed with silver nitrate and tetrachloroauric acid solution at different reagent ratios to optimize the synthesis process. The resulting bimetallic nanoparticles (AgAuNPs) were characterized using UV-vis spectrophotometry, transmission electron microscopy, atomic absorption spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of the biosynthesized AgAuNPs was evaluated against various strains of Pseudomonas aeruginosa. The minimal inhibitory concentration (MIC) was determined using a microcultivation device, and the minimal bactericidal concentration (MBC) was determined through subsequent solid medium cultivation. Additionally, the minimal biofilm inhibitory concentration (MBIC) was assessed using a polystyrene microtiter plate as biofilm carrier and measured through an assay determining the metabolic activity of biofilm cells. The results demonstrated successful synthesis of bimetallic nanoparticles using the extracts from Cannabis sativa and Vitis vinifera waste. The AgAuNPs exhibited significant antimicrobial activity against the tested Pseudomonas aeruginosa strains, inhibiting their growth and biofilm formation. These findings highlight the potential of waste valorization and circular economy in nanoparticle production and their application as effective antimicrobial agents. This study contributes to the growing field of sustainable nanotechnology and provides insights into the utilization of plant waste extracts for the synthesis of bimetallic nanoparticles with antimicrobial properties. The findings support the development of eco-friendly and cost-effective approaches for nanoparticle production while addressing the challenges of waste management and combating microbial infections.

Aims: The study aimed to explore the sustainable synthesis of metal nanoparticles using a green and eco-friendly resource. Specifically, it investigated the utilization of Cannabis sativa waste extract for the production of gold and silver nanoparticles, focusing on their antimicrobial activity against gram-negative bacteria, particularly Pseudomonas aeruginosa strains, which are significant in nosocomial infections. Methods: Cannabis sativa waste extract was employed to synthesize gold and silver nanoparticles through a green synthesis approach. The produced nanoparticles were characterized using transmission electron microscopy (TEM), atomic absorption spectrometry (AAS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The antimicrobial efficacy of the synthesized nanoparticles was assessed through their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) against Pseudomonas aeruginosa, utilizing a microcultivation device, solid medium cultivation, and a metabolic activity assay in a polystyrene microtiter plate, respectively. Results: The TEM analysis revealed the size and morphology of the nanoparticles, while AAS confirmed their concentration. XRD provided insights into the crystalline structure, and FTIR analysis identified the molecular structure of the nanoparticle’s stabilizing layer. The synthesized nanoparticles showed significant antimicrobial activity against Pseudomonas aeruginosa, with determined MIC, MBC, and MBIC values of produced silver nanoparticles, showcasing their potential as effective antimicrobial agents. Conclusions: This study successfully demonstrated the synthesis of silver and gold nanoparticles using Cannabis sativa waste extract and highlighted their potent antimicrobial properties. It underscores the potential of utilizing plant waste extracts in sustainable nanomaterial synthesis and contributes to the fields of green nanotechnology and waste valorization within the circular economy. The findings also offer valuable insights into developing natural waste source-based antimicrobial agents.