A mini-review on indigenous microbial biofilm from various wastewater for heavy-metal removal - new trends.

Biofilm, as a form of the microbial community in nature, represents an evolutionary adaptation to the influence of various environmental conditions. In nature, the largest number of microorganisms occur in the form of multispecies biofilms. The ability of microorganisms to form a biofilm is one of the reasons for antibiotic resistance. The creation of biofilms resistant to various contaminants, on the other hand, improves the biological treatment process in wastewater treatment plants. Heavy metals cannot be degraded, but they can be transformed into non-reactive and less toxic forms. In this process, microorganisms are irreplaceable as they interact with the metals in a variety of ways. The environment polluted by heavy metals, such as wastewater, is also a source of undiscovered microbial diversity and specific microbial strains. Numerous studies show that biofilm is an irreplaceable strategy for heavy metal removal. In this review, we systematize recent findings regarding the bioremediation potential of biofilm-forming microbial species isolated from diverse wastewaters for heavy metal removal. In addition, we include some mechanisms of action, application possibilities, practical issues, and future prospects.

Response of selected microbial strains and their consortia to the presence of automobile paints: Biofilm growth, matrix protein content and hydrolytic enzyme activity.

The goal of the current study was to examine the effects of pollutants (White color - CP; Metallic red color - FM; Thinner - CN; Thinner for rinsing paint - MF; Basic color (primer) - FH) originating from the automotive industry on the biofilm growth, matrix protein content, and activity of the hydrolytic enzymes of selected microbial strains in laboratory conditions that mimic the bioreactor conditions. The chosen microorganisms (bacteria, yeasts, and fungi) were isolated from automotive industry wastewater. Pure microbe cultures and their consortia were injected into AMB Media carriers and developed into biofilms. The use of AMB media carriers has been linked to an increase in the active surface area colonized by microorganisms. Afterwards, the carriers were transferred to Erlenmeyer flasks with nutrient media and pollutants at a concentration of 200 µL/mL. The current study found that, depending on the microbial strain, development phase, and chemical structure, the assessed pollutants had an inhibitory or stimulatory influence on the growth of single cultures and their consortia. Statistical analysis found positive correlations between the protein content in the matrix and the biofilm biomass of Rhodotorula mucilaginosa and consortia in CP and FH media, respectively. The proteolytic activity of Candida utilis was very pronounced in media with MF and CN. The best alkaline phosphatase activity (ALP) was achieved in the CN medium of R. mucilaginosa. Acid invertase activity was the highest in the FM and CP media of Escherichia coli and consortia, respectively, whereas the highest alkaline invertase activity was measured in the MF medium of E. coli. A positive correlation was confirmed between ALP and the biofilm biomass of R. mucilaginosa in CP and CN media, as well as between ALP and the biofilm biomass of Penicillium expansum in FM medium. The findings provide novel insights into the extracellular hydrolytic activity of the investigated microbial strains in the presence of auto paints, as well as a good platform for subsequent research into comprehensive biofilm profiling using modern methodologies.

Great horsetail (Equisetum telmateia Ehrh.): Active substances content and biological effects.

This paper deals with the antioxidant and antimicrobial activity, total phenolic content and concentrations of flavonoids of Equisetum telmateia extracts. Total phenolic content was determined with Folin-Ciocalteu reagent and it ranged between 129.0 to 262.7 mg GA/g. The concentration of flavonoids in various extracts of E. telmateia was determined using spectrophotometric method with aluminum chloride and obtained results varied from 112.6 to 199.8 mg RU/g. Antioxidant activity was monitored spectrophotometrically and expressed in terms of IC50 (µg/ml), and its values ranged from 33.4 to 982.2 µg/ml. The highest phenolic content, concentrations of flavonoids and capacity to neutralize DPPH radicals were found in the acetone extract. In vitro antimicrobial activity was determined using microdilution method. Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were also determined. Testing was performed on 22 microorganisms, including 15 strains of bacteria (standard and clinical strains) and 7 species of fungi. There were statistically significant differences in activity between the extracts of E. telmateia. Different effects were noticed against the bacteria and the methanol extract appeared to be most efficient. All the extracts showed significant antibacterial activity against G+ bacteria and weak to moderate activity against other microorganisms.