Microbial Life on the Surface of Microplastics in Natural Waters

Major water-polluting microplastics (for example, polyethylene, polypropylene and others) have lower density than water. Therefore, they are concentrated in the neustonic layer near the water-air interface altogether with dissolved or colloidal natural organic matter, hydrophobic cells and spores of bacteria. This can cause environmental and public health problems because the floating micro- and nanoparticles of plastics could be coated with biofilm of hydrophobic and often putative pathogenic bacteria. Biofilm-coated microplastics are more attractive for consumption by aquatic animals than pure microplastics, and that increases the negative impacts of microplastics. So, impacts of even small quantities of microplastics in aquatic environments must be accounted for considering their accumulation in the micro-layer of water-air interphase and its interaction with bacterioneuston. Microorganisms attached to the surface of microplastic particles could interact with them, use them as substrates for growth, to change properties and biodegrade. The study of microbial life on the surface of microplastic particles is one of the key topics to understanding their role in the environment

Spectroscopic Studies of Interactions of Iron Oxide Nanoparticles with Ovalbumin Molecules

Recent studies show the possibility of using iron oxide nanoparticles as a food additive with certain functional and technological properties. However, when developing technologies for food products, the interaction of these particles with the main components of the food matrix, in particular proteins, takes on special significance. The aim of the present research was to study the interaction of iron oxide nanoparticles with ovalbumin molecules. Fourier-transform infrared and fluorescence spectroscopy were used to study interaction between iron oxide nanoparticles and ovalbumin molecules. It was found that the interaction of iron oxide nanoparticles with ovalbumin molecules occurs via a mechanism of static quenching with the formation of an intermolecular nonfluorescent complex that changes the native structure of the protein. The binding constant varied from 3.6 × 104 to 4.1 × 104 L·mol−1 depending on the pH value of the medium and temperature. The calculated thermodynamic parameters of binding indicate the spontaneity of the process with the predominance of the enthalpy factor. The interaction between iron nanoparticles and ovalbumin occurred mainly due to the presence of electrotatic forces. The obtained data on the mechanism of interaction of iron oxide nanoparticles with proteins should be taken into account when developing food technologies to control functional properties of products

Microbial Life on the Surface of Microplastics in Natural Waters

Major water-polluting microplastics (for example, polyethylene, polypropylene and others) have lower density than water. Therefore, they are concentrated in the neustonic layer near the water-air interface altogether with dissolved or colloidal natural organic matter, hydrophobic cells and spores of bacteria. This can cause environmental and public health problems because the floating micro- and nanoparticles of plastics could be coated with biofilm of hydrophobic and often putative pathogenic bacteria. Biofilm-coated microplastics are more attractive for consumption by aquatic animals than pure microplastics, and that increases the negative impacts of microplastics. So, impacts of even small quantities of microplastics in aquatic environments must be accounted for considering their accumulation in the micro-layer of water-air interphase and its interaction with bacterioneuston. Microorganisms attached to the surface of microplastic particles could interact with them, use them as substrates for growth, to change properties and biodegrade. The study of microbial life on the surface of microplastic particles is one of the key topics to understanding their role in the environment

Isolation and characterization of thermoactive extracellular protease-producing geobacillus caldoproteolyticus sp. nov. from sewage sludge

A proteolytic thermophilic bacterial strain, designated as strain SF03, was isolated from sewage sludge in Singapore. Strain SF03 is strictly aerobic, rod-shaped, Gram- positive, catalase positive, oxidase positive, and forms endospores. Strain SF03 grew at temperatures ranging from 35 to 65 OC, pH ranging from 6.0 to 9.0 and salinities ranging from 0 to 2.5%. Phylogenetic analyses revealed that strain SF03 was most similar to Saccharococcus themophilus, Geobacillus caldoxylosilyticus and Geobacillus thermoglucosidasius, with the 16s rRNA gene sequence identity of 97.6%, 97.5% and 97.2%, respectively. Based on taxonomic and 16s rRNA analysis data, strain SF03 was named Geobacillus caldoproteolyticus sp. nov. Production of extracellular protease from strain SF03 was observed in a basal peptone medium and the peptone medium supplemented with different carbon and nitrogen sources. Different levels of protease production were found with different carbon and nitrogen sources

Wastewater engineering applications of BioIronTech process based on the biogeochemical cycle of iron bioreduction and (bio)oxidation

Bioreduction of Fe(III) and biooxidation of Fe(II) can be used in wastewater engineering as an innovative biotechnology BioIronTech, which is protected for commercial applications by US patent 7393452 and Singapore patent 106658 “Compositions and methods for the treatment of wastewater and other waste”. The BioIronTech process comprises the following steps: 1) anoxic bacterial reduction of Fe(III), for example in iron ore powder; 2) surface renovation of iron ore particles due to the formation of dissolved Fe2+ ions; 3) precipitation of insoluble ferrous salts of inorganic anions (phosphate) or organic anions (phenols and organic acids); 4) (bio)oxidation of ferrous compunds with the formation of negatively, positively, or neutrally charged ferric hydroxides, which are good adsorbents of many pollutants; 5) disposal or thermal regeration of ferric (hydr)oxide. Different organic substances can be used as electron donors in bioreduction of Fe(III). Ferrous ions and fresh ferrous or ferric hydroxides that are produced after iron bioreduction and (bio)oxidation adsorb and precipitate diferent negatively charged molecules, for example chlorinated compounds of sucralose production wastewater or other halogenated organics, as well as phenols, organic acids, phosphate, and sulphide. Reject water (return liquor) from the stage of sewage sludge dewatering on municipal wastewater treatment plants represents from 10 to 50% of phosphorus load when being recycled to the aeration tank. BioIronTech process can remove/recover more than 90% of phosphorous from this reject water thus replacing the conventional process of phosphate precipitation by ferric/ferrous salts, which are 20–100 times more expensive than iron ore, which is used in BioIronTech process. BioIronTech process can remarkably improve the aerobic and anaerobic treatments of municipal and industrial wastewaters, especially anaerobic digestion of lipid- and sulphate-containing food-processing wastewater. It can also remove the recalcitrant compounds from industrial wastewater, enhance sustainability and quality of water resources,restore eutrophicated lakes due to removal of phosphate, ammonium, and pesticides from water, and recover ammonium and phosphate from municipal and food-processing wastes