The bioavailability of organic compounds to bacterial cells is crucial for their vital activities. This includes both compounds that are desirable to the cells (e.g., sources of energy, carbon, ...nitrogen, and other nutrients) and undesirable compounds that are toxic to the cells. For this reason, bioavailability is an issue of great importance in many areas of human activity that are related to bacteria, e.g., biotechnological production, bioremediation of organic pollutants, and the use of antibiotics. This article proposes a classification of factors determining bioavailability, dividing them into factors at the physicochemical level (i.e., those related to the solubility of a chemical compound and its transport in aqueous solution) and factors at the microbiological level (i.e., those related to adsorption on the cell surface and those related to transport into the cell). Awareness of the importance of and the mechanisms governing each of the factors described allows their use to change bioavailability in the desired direction.
The possibility of removing bisphenol A and its five potential substitutes (bisphenols S, F, AF, E, and B) was tested using microorganism consortia from river water and activated sludge from ...municipal and rural wastewater treatment plants. For most bisphenols, biodegradation with activated sludge was faster than with river water and a greater extent of biodegradation was also achieved. However, only bisphenol A and bisphenol F underwent 100% primary biodegradation while other bisphenols degraded no more than about 50% which has some important implications in case of their increased usage. Metabolic activity in biodegradation liquors was also tested and it showed higher activity in the tests with activated sludge than with river water. However, there was no clear connection between the decline of metabolic activity and the extent of biodegradation as decreased activity was observed for two easily degrading bisphenols and two others with little biodegradability. It can be assumed that two different phenomena are involved in this process including depletion of nutrients for easily degradable bisphenol A and absence of nutrients for bacteria incapable of primary degradation of bisphenol AF and bisphenol S.
Despite many years of efforts to reduce the emission of toxic pollutants into the environment, the contamination of air, soils and water by heavy metals and organic xenobiotics is still a serious ...problem. This has urged many scientists around the world to undertake research that aims to find effective methods of removing pollutants from the environment. Special attention is paid to biological methods, which, thanks to their numerous advantages, meet the expectations of the whole society. As part of the Special Issue “Study of Biodegradation and Bioremediation”, in the MDPI journal Processes, several valuable articles have been published, which together form a picture of the current state of advanced research on the effective fight against environmental pollution. These include papers on the biodegradation of petroleum compounds or synthetic dyes by microorganisms or the enzymes they produce. In addition, the Special Issue includes papers on the bioremediation of dangerous heavy metals such as mercury and copper, and the results make a valuable contribution to our current state of knowledge on this topic. A separate and valuable part of this collection of publications are review articles devoted to the remediation of antineoplastic drugs, as well as the hopes and challenges connected with the application of nanotechnology in bioremediation. We are pleased that so many researchers from different parts of the world have submitted their articles on this topic. We are very grateful to them. We hope that readers of this collection will find many interesting ideas and relevant information that will lead to new solutions in the bioremediation and biodegradation of emerging environmental contaminants. Prof. Ewa Kaczorek Dr. Wojciech Smułek
Vitamin D
and iron are important components of a balanced diet. Supplementing meals with these is essential to support the recovery of humankind’s malnutrition. It is necessary to develop effective ...delivery systems to ensure the high bioavailability of these hydrophobic components. For this purpose, emulsions were prepared based on hemp seed oil and with soap nut extract (
fruits) as a natural emulsifier. To characterize the differences in the properties of the emulsions depending on the content of the oil phase and the emulsifier, measurements were performed to determine the following parameters: the color characteristics, transparency of the samples, infrared spectrum, particle size distribution, polydispersity of the system, and the rheological properties of the emulsions. The results showed that the highest stability was observed in systems with a relatively low oil concentration,
, 1%. These samples also had an average particle size not exceeding 200 nm. In turn, the low oil content significantly reduced the dynamic viscosity of the emulsions. At the same time, microscopic observations indicated that the presence of an oil phase was advantageous, not only because of the possibility of providing vitamin D but also because of the high hydrophobicity of the iron particles. Therefore, the realized research made it possible to identify the optimal emulsion composition. The created system can find applications in delivering dietary supplements such as vitamin D
and iron by providing high dispersion of components and high stability.
The environment pollution with hydrophobic hydrocarbons is a serious problem that requires development of efficient strategies that would lead to bioremediation of contaminated areas. One of the ...common methods used for enhancement of biodegradation of pollutants is the addition of biosurfactants. Several mechanisms have been postulated as responsible for hydrocarbons bioavailability enhancement with biosurfactants. They include solubilization and desorption of pollutants as well as modification of bacteria cell surface properties. The presented review contains a wide discussion of these mechanisms in the context of alteration of bioremediation efficiency with biosurfactants. It brings new light to such a complex and important issue.
Ibuprofen is one of the most often detected pollutants in the environment, particularly at landfill sites and in wastewaters. Contamination with pharmaceuticals is often accompanied by the presence ...of other compounds which may influence their degradation. This work describes the new degradation pathway of ibuprofen by
B1(2015b), focusing on enzymes engaged in this process. It is known that the key intermediate which transformation limits the velocity of the degradation process is hydroxyibuprofen. As the degradation rate also depends on various factors, the influence of selected heavy metals and aromatic compounds on ibuprofen degradation by the B1(2015b) strain was examined. Based on the values of non-observed effect concentration (NOEC) it was found that the toxicity of tested metals increases from Hg(II) < Cu(II) < Cd(II) < Co(II) < Cr(VI). Despite the toxic effect of metals, the biodegradation of ibuprofen was observed. The addition of Co
ions into the medium significantly extended the time necessary for the complete removal of ibuprofen. It was shown that
B1(2015b) was able to degrade ibuprofen in the presence of phenol, benzoate, and 2-chlorophenol. Moreover, along with the removal of ibuprofen, degradation of phenol and benzoate was observed. Introduction of 4-chlorophenol into the culture completely inhibits degradation of ibuprofen.
The aim of this study was to determine the effect of saponins-rich plant extract on two model biological membranes: phospholipid monolayers and liposomes. The Langmuir monolayer technique was used to ...study the interactions of model phospholipid membranes with saponins. The π-A isotherms were determined for DPPE (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine) monolayer with the addition of various concentrations of licorice saponins extracts and subjected to qualitative as well as quantitative analysis. Additionally, relaxation studies of the obtained monolayers were carried out and morphological changes were examined using Brewster angle microscopy. Moreover, changes in the structure of phospholipid vesicles treated with solutions of saponins-rich plant extracts were assessed using the FTIR technique. The size and zeta potential of the liposomes were estimated based on DLS methods. The obtained results indicated that the saponins interact with the phospholipid membrane formed by DPPE molecules and that the stability of the mixed DPPE/saponins monolayer strongly depends on the presence of impurities in saponins. Furthermore, it was found that the plant extract rich in saponins biosurfactant interacts mainly with the hydrophilic part of liposomes.
The amounts of antibiotics of anthropogenic origin released and accumulated in the environment are known to have a negative impact on local communities of microorganisms, which leads to disturbances ...in the course of the biodegradation process and to growing antimicrobial resistance. This mini-review covers up-to-date information regarding problems related to the omnipresence of antibiotics and their consequences for the world of bacteria. In order to understand the interaction of antibiotics with bacterial membranes, it is necessary to explain their interaction mechanism at the molecular level. Such molecular-level interactions can be probed with Langmuir monolayers representing the cell membrane. This mini-review describes monolayer experiments undertaken to investigate the impact of selected antibiotics on components of biomembranes, with particular emphasis on the role and content of individual phospholipids and lipopolysaccharides (LPS). It is shown that the Langmuir technique may provide information about the interactions between antibiotics and lipids at the mixed film surface (π–A isotherm) and about the penetration of the active substances into the phospholipid monolayer model membranes (relaxation of the monolayer). Effects induced by antibiotics on the bacterial membrane may be correlated with their bactericidal activity, which may be vital for the selection of appropriate bacterial consortia that would ensure a high degradation efficiency of pharmaceuticals in the environment.
The aim of this research was to elucidate the surface active properties of
(soapwort) extract containing the plant surfactants saponins. To this end, the advancing contact angle (θ) of water, ...formamide and diiodomethane on the glass, as well as θ of the aqueous solution of
extract fractions on PTFE, PMMA and glass, were studied. Based on the obtained results, the wetting behaviour of saponins was considered with regard to the surface tension components and parameters of the solutions and solids. The investigations also involved the description of the θ isotherms, the dependences between the cosine of contact angle and/or the adhesion of the solution to the solid surfaces and solution surface tension, as well as the critical surface tension of PTFE, PMMA and glass wetting. These dependences were studied based on the saponin adsorption at the different interfaces, which was deduced from the dependence between the adhesion and surface tension of the solution, as well as using the Gibbs and Frumkin isotherm equations. This proved that the saponins are poor wetting agents and that the contact angle isotherm can be described by the exponential function of the second order as well as the Szyszkowski equation, but only for PTFE.
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