Microbial Prions: Dawn of a New Era

Protein misfolding and aggregation are associated with human diseases and aging. However, microorganisms widely exploit the self-propagating properties of misfolded infectious protein particles, prions, as epigenetic information carriers that drive various phenotypic adaptations and encode molecular information. Microbial prion research has faced a paradigm shift in recent years, with breakthroughs that demonstrate the great functional and structural diversity of these agents. Here, we outline unorthodox examples of microbial prions in yeast and other microorganisms, focusing on their noncanonical functions. We discuss novel molecular mechanisms for the inheritance of conformationally-encoded epigenetic information and the evolutionary advantages they confer. Lastly, in light of recent advancements in the field of molecular self-assembly, we present a hypothesis regarding the existence of non-proteinaceous prion-like entities.

Perspectives of future water sources in Qatar by phytoremediation: biodiversity at ponds and modern approach

Anthropogenic and industrial wastewater (IWW) could be an additional future source of water to support the needs of the people of the State of Qatar. New lagoons have been built using modern technologies to optimize water use and waste recycling, as well as increasing the green spaces around the country. To achieve successful development of these new lagoons, lessons should be learned from the old ponds by examining their biodiversity, ecology, and the roles played by aquatic plants and algae to remediate wastewaters at these ponds. The perspectives of using IWW (from oil and gas activities), that is currently pumped deep into the ground are presented. Instead of causing great damage to groundwater, IWW can be stored in artificial ponds prepared for ridding it of all impurities and pollutants of various types, organic and inorganic, thereby making it serviceable for various human uses. Phycoremediation, bioremediation, and phytoremediation methods adopted by algae, bacteria and aquatic native plants are discussed, and special attention should be paid to those that proved successful in removing heavy metals and degrading organic compounds. At least three native plants namely: Amaranthus viridis, Phragmites australis, and Typha domingensis should be paid special attention, since these plants are efficient in remediation of arsenic and mercury; elements found abundantly in wastewater of gas activities. Some promising modern and innovative experiences and biotechnologies to develop efficient transgenic plants and microorganisms in removing and degrading pollutants are discussed, as an important strategy to keep the ecosystem clean and safe. Novelty statementIndustrial wastewater (IWW) could be an alternative source of water at the Arabian Gulf region. Currently, IWW is pumped deep into the ground causing a great damage to groundwater; little information about this issue has been reported. Such IWW can be stored in artificial ponds designed for ridding them of all impurities of various types; various remediation methods can be used. Modern biotechnology to develop transgenic plants and microorganisms to enhance these remediation methods can be adopted.

[Effects of ant disturbance on soil organic carbon cycle: A review.]

The impact of ants, as consumer and decomposer in ecosystems, on soil organic carbon pool is a hotspot in soil fauna research. Recently, effects of ants on soil organic carbon pool dynamics have been mainly documented in terms of soil macro-elements storage, physical and chemical properties, and microbial community. We summarized the effects of ant disturbance on soil organic carbon cycle. Ant nesting alters microhabitat, microclimate, and physicochemical properties of ant nested soils. By re-shaping soil microbial community structure, regulating the succession process and pattern of vegetation, ant nesting directly or indirectly affects the source, allocation, stability, and microcosmic molecular characteristics of soil organic carbon, scaling from micro, local, to landscape scale. In the future, more attentions should be paid on quantifying the contribution of ant disturbance combined with the fluctuations in environmental factors to soil carbon flux dynamics, establishing quantitative model to link and unify ant-induced soil carbon cycle process, and clari-fying mechanisms underlying the impacts of ants on the stability of soil organic carbon pool, and finally revealing the "ecological engineers" role of ants in regulating soil organic carbon cycling.

Colonization of methicillin-resistant Staphylococcus aureus among healthcare students: an integrative review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a worldwide concern given its presence even in non-hospitalized healthy individuals, such as university students.

OBJECTIVE

To identify in the literature the prevalence of colonization by MRSA among healthcare students.

DESIGN AND SETTING

Integrative review of the literature conducted in Universidade Federal do Piauí.

METHOD

A search for primary studies was performed in the following databases: Medical Literature Analysis and Retrieval System on-line; Cumulative Index to Nursing and Allied Health Literature; Web of Science; Scopus; and LILACS.

RESULTS

This review included 27 studies that demonstrated MRSA infection prevalence ranging from 0.0 to 15.3% among students.

CONCLUSION

The prevalence of colonization of MRSA among healthcare students is high, and the nasal cavity was cited as an important reservoir location for these microorganisms.

Vaccines For Type 1 Diabetes: Prevention or Reversal?

Type 1 diabetes mellitus (T1DM) is an autoimmune disease which leads to the destruction of pancreatic β-cells, thereby causing insufficient insulin production. Globally, around 98, 200 children and adolescents below 15 years of age and almost 128,900 subjects below 20 years of age develop T1DM annually, along with severe complications deteriorating their quality of life. In India alone, around 15,900 incident cases below 15 years have reported annually. Hence, its prevention and reversal are significant. Unlike other chronic diseases, T1DM involves the presence of various autoantigens, which can be targeted by proper immunisation. The development of reliable immuno-regulatory surrogate markers would be of great benefit. Vaccines can be one of such strategies in the journey to prevent T1DM. It would not only benefit greatly to reduce the sufferings caused due to diabetic complications but could also help to reverse T1DM, by modulating the autoantigenic immunological reactions and prevent further degradation of pancreatic β-cells. This review collates a wide range of information related to the vaccine studies conducted in animal and human models to prevent and reverse T1DM.

Macrolactin Antibiotics: Amazing Natural Products

The resistance among various microbial species (infectious agents) to different antimicrobial drugs has emerged as a cause of serious public health problem all over the world. In this sense, natural products have been a rich source of compounds for drug discovery with antibiotic activity. Macrolactins are amazing structures which have antibiotic activity against some clinically relevant pathogens. In addition, they have anti-inflammatory, antifungal, antimicrobial, and antitumor activities. They are macrolides containing 24-membered lactone ring with some differences in their chemical structures. The synthesis of these compounds is a difficult task which has attracted attention of researchers; however few syntheses have been reported. In this review, the isolation of all reported macrolactins, their syntheses and biological activities are revisited.

[Integrative microbial-zoological assessment of the postmortem period in forensic medical examination]

THE AIM OF THE STUDY

Is a complex microbial-zoological characterization of the post-mortal period and ways of its determination during forensic examination. The heterotrophic component of the microflora of the corpse and its bed were studied using standard methods of microbiological research and PCR analysis, necrophilic insects - entomological method, and damages from some vertebrate animals - traditional methods of their analysis. We studied 125 corpses of humans, pigs, chickens, mice and some other representatives of mammal class weighing from 100 g to 100 kg at different times of decomposition. We isolated and studied more than 1000 isolates of microorganisms, more than 32 000 insects and more than 100 damages caused by rodents, dogs, cats and birds. We determined the main trends in microbial decomposition of dead bodies. The general characteristics of the corpse decomposition by insects are given and anatomical-topographical and morphological features of the corpse damage by some vertebrates are established. Significant The heterotrophic component of the microflora of the corpse and its bed were studied using standard methods of microbiological research and PCR analysis, necrophilic insects - entomological method, and damages from some vertebrate animals - traditional methods of their analysis. We studied 125 corpses of humans, pigs, chickens, mice and some other representatives of mammal class weighing from 100 g to 100 kg at different times of decomposition. We isolated and studied more than 1000 isolates of microorganisms, more than 32 000 insects and more than 100 damages caused by rodents, dogs, cats and birds. We determined the main trends in microbial decomposition of dead bodies. The general characteristics of the corpse decomposition by insects are given and anatomical-topographical and morphological features of the corpse damage by some vertebrates are established. Significant microbial and zoological characteristics of the post-mortem period have been identified, and ways of its establishment have been determined and confirmed by practical testing during forensic examination. A set of practical recommendations has been developed for forensic experts on the collection of necrophilous insects during the examination of the corpse at the scene and the tactics of the examination with the involvement of entomologists. The results obtained prove that there is a close correlation between the impact of vertebrate scavengers, necrophilic insects and the enzymatic activity of a specific community of heterotrophic microorganisms on the corpse.

Application of a Medical Diode Laser (810 nm) for Disinfecting Small Microbiologically Contaminated Spots on Degraded Collagenous Materials for Improved Biosafety in Objects of Exceptional Historical Value From the Auschwitz-Birkenau State Museum and Protection of Human Health

The research aim was to optimize the operating parameters of a diode laser irradiation for the effective disinfection of degraded collagenous materials. Historical leather shoes stored at the Auschwitz-Birkenau State Museum in Oświęcim (Poland) were the main study objects. Surfaces of contaminated small spots occurring on the degraded materials were sampled with moistened swabs and microbiologically examined using the molecular techniques MALDI-TOF MS, 16S rRNA, and NGS sequencing. The surfaces were colonized by bacteria with 10⁶ CFU/100 cm² and 10⁴ CFU/100 cm² by fungi, on average. Microorganisms of the genera Bacillus and Penicillium were predominant. The effectiveness of the laser treatment was assessed for the new and degraded collagenous materials against isolated environmental strains using four variants of exposure time and number of repetitions. 0.3 W/CW 2 × 2 min variant was the most effective and also did not noticeably change the color of the treated samples. The variant caused a reduction in the numbers of microorganisms by 96–100%. After 1 month, four types of leather were subjected to comprehensive physico-chemical analyses. SEM and FTIR techniques confirmed that laser irradiation in the selected optimal variant did not affect the surface morphology and collagen structure, while XPS technique enabled detection of subtle changes in non-historical protective coatings on the surfaces of tested degraded historical materials.

DetR DB: A Database of Ionizing Radiation Resistance Determinants

Nuclear pollution is an urgent environmental issue and is a consequence of rapid industrialization and nuclear accidents in the past. Remediation of nuclear polluted sites using microbial vital activity (bioremediation) is a promising approach to recover contaminated areas in an environmentally friendly and cost-saving way. At the same time, the number of known bacterial and archaeal species able to withstand extremely high doses of ionizing radiation (IR) is steadily growing every year, together with growing knowledge about mechanisms of radioresistance that opens up opportunities for developing new biotechnological solutions. However, these data are often not systemized, and can be difficult to access. Here, we present the Determinants of Radioresistance Database, or DetR DB, gathering a comprehensive catalog of radioresistant microbes and their molecular and genetic determinants of enhanced IR tolerance. The database provides search tools, including taxonomy, common gene name, and BLAST. DetR DB will be a useful tool for the research community by facilitating the extraction of the necessary information to help further analysis of radiation-resistant mechanisms.

Effects of Oat Hay Content in Diets on Nutrient Metabolism and the Rumen Microflora in Sheep

Oats have the characteristics of drought tolerance, cold resistance, strong adaptability, high forage yield, and high nutritional value. However, there are few reports on the most appropriate amount of oat hay in ruminant diets, the digestion and metabolism of ruminants, and the rumen microflora. To study the effects of oat hay content in diets on nutrient digestion and metabolism and the rumen microflora in sheep, 9 German Merino and Mongolian crossbred rams of similar body condition and weight with permanent fistulas were selected. The 3 × 3 Latin square design was used to randomly divide the rams into 3 groups, with 3 animals in each group. The three groups were fed different kinds of roughage: whole-plant corn silage only (corn silage group, CSG), oat hay mixed with whole-plant corn silage (1:1) (mixed group, MG), and oat hay only (oat hay group, OHG). The nutrient digestion and metabolism of each group were measured, and the pH and rumen microflora were examined after feeding for different durations. Dynamic changes in microbial communities were detected. The nutrient digestion and metabolism results showed that, with an increase in the content of oat hay in the diet, the intake and apparent digestibility of dry matter (DM) and organic matter (OM) showed an increasing trend, and the intake, digestion, and stability of acid detergent fiber (ADF) and neutral detergent fiber (NDF) increased in the OHG. The apparent digestibility, dietary nitrogen, deposited nitrogen, and nitrogen retention rate in this group were significantly higher than those in the CSG (p < 0.05). The rumen pH and sequencing results showed that the rumen fluid pH of the CSG was significantly lower than that of the OHG at 1 and 5 h (p < 0.05). The main microbial in the rumen of the three groups of sheep were Bacteroides, Sclerotium, and Proteus. The dominant taxon in the CSG was Prevotella, followed by Vibrio syringae, and the dominant taxon in the MG and OHG was Prevotella, followed by Rikenellaceae. Redundancy analysis showed that ADF and NDF in the feed had an effect on the abundance of Fibrobacteres, Ruminococcaceae, and Prevotella. Our findings indicate that the use of oat hay roughage in the diet significantly improves the apparent digestibility of NDF and ADF and helps maintain the stable state of the sheep's rumen internal environment and the growth of rumen microorganisms.

Antifungal and antiovarian cancer properties of α Fe2O3 and α Fe2O3/ZnO nanostructures synthesised by Spirulina platensis

Candida albicans (C. albicans) infection shows a growing burden on human health, and it has become challenging to search for treatment. Therefore, this work focused on the antifungal activity, and cytotoxic effect of biosynthesised nanostructures on human ovarian tetracarcinoma cells PA1 and their corresponding mechanism of cell death. Herein, the authors fabricated advanced biosynthesis of uncoated α-Fe2O3 and coated α-Fe2O3 nanostructures by using the carbohydrate of Spirulina platensis. The physicochemical features of nanostructures were characterised by UV-visible, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The antifungal activity of these nanostructures against C. albicans was studied by the broth dilution method, and examined by 2', 7'-dichlorofluorescein diacetate staining. However, their cytotoxic effects against PA1 cell lines were evaluated by MTT and comet assays. Results indicated characteristic rod-shaped nanostructures, and increasing the average size of α-Fe2O3@ZnO nanocomposite (105.2 nm × 29.1 nm) to five times as compared to α-Fe2O3 nanoparticles (20.73nm × 5.25 nm). The surface coating of α-Fe2O3 by ZnO has increased its antifungal efficiency against C. albicans. Moreover, the MTT results revealed that α-Fe2O3@ZnO nanocomposite reduces PA1 cell proliferation due to DNA fragmentation (IC50 18.5 μg/ml). Continual advances of green nanotechnology and promising findings of this study are in favour of using the construction of rod-shaped nanostructures for therapeutic applications.

Application of next generation sequencing-based rapid detection platform for microbiological diagnosis and drug resistance prediction in acute lower respiratory infection

Background

Acute lower respiratory infections (ALRIs) have a high mortality rate. We aimed to apply a platform that rapidly detects 36 microorganisms and 49 antibiotic resistance markers in the clinical diagnosis of ALRI and drug resistance prediction.

Methods

Multicenter collection of clinical samples from patients with ALRIs was carried out from 2017 to 2018. Sputum culture (SC) was performed, which provided two outcomes: the detected pathogens and the resistance to different antibiotics. Additionally, each sputum sample was used to extract deoxyribonucleic acids (DNAs) followed by high-throughput sequencing.

Results

Eleven commonly observed pathogens were surveyed, and for all samples with positive SC results (137 cases), the overall coverage was 95.62% according to the sequencing results. The receiver operating characteristic (ROC) curve was drawn, and cutoff reads of the most frequently detected pathogens were acquired. Overall, sequencing exhibited significantly higher sensitivity in the detection of pathogens compared with the traditional SC method, with a generally satisfactory specificity. Furthermore, we investigated the correlation between antibiotic resistance gene phenotypes and the actual outcomes of the drug sensitivity test, and some significant correlations were found, especially for the resistance to Amikacin in the presence of blaOXA7.

Conclusions

Sequencing-based sputum metagenomics can reveal a profile of the lung pathogen microbiome. The sequencing method offers both sufficient accuracy and significantly higher sensitivity in the detection of pathogens, and can be at least a complementary approach to traditional SC reporting. The sequencing technique also revealed some novel potential correlations between the presence of different pathogens, as well as new antimicrobial-resistant genes.

Greater topoclimatic control of above- versus below-ground communities

Assessing the degree to which climate explains the spatial distributions of different taxonomic and functional groups is essential for anticipating the effects of climate change on ecosystems. Most effort so far has focused on above-ground organisms, which offer only a partial view on the response of biodiversity to environmental gradients. Here including both above- and below-ground organisms, we quantified the degree of topoclimatic control on the occurrence patterns of >1,500 taxa and phylotypes along a c. 3,000 m elevation gradient, by fitting species distribution models. Higher model performances for animals and plants than for soil microbes (fungi, bacteria and protists) suggest that the direct influence of topoclimate is stronger on above-ground species than on below-ground microorganisms. Accordingly, direct climate change effects are predicted to be stronger for above-ground than for below-ground taxa, whereas factors expressing local soil microclimate and geochemistry are likely more important to explain and forecast the occurrence patterns of soil microbiota. Detailed mapping and future scenarios of soil microclimate and microhabitats, together with comparative studies of interacting and ecologically dependent above- and below-ground biota, are thus needed to understand and realistically forecast the future distribution of ecosystems.

Mixed culture of Lactococcus lactis and Kluyveromyces marxianus isolated from kefir grains for pollutants load removal from Jebel Chakir leachate

The wastewater from the dumping site usually contains high pollutant levels. Biological process and physico-chemical treatments are among several technologies for wastewater treatment. Using microorganisms in the treatment of landfill leachate is an emerging research issue. Furthermore, bioremediation is a feasible approach for pollutants removal from landfill leachate which would provide an efficient way to resolve the issue of landfill leachate. In this study, the performance of yeast and bacteria isolated from kefir grains was assessed for landfill leachate treatment. Kefir grains microbial composition was evaluated by molecular approaches (Rep-PCR and 16S rRNA gene sequencing). The obtained outcomes denoted that high concentrations of lactic acid bacteria and yeast populations (over 10⁷  CFU/ml) were found in the kefir grains and were essentially composed of Lactococcus lactis, Lactobaccillus kefirien, bacillus sp., L. lactis, and Kluyveromyces marxianus. The co-culture with 1% of inoculum size was demonstrated as the most efficient in the degradation of different contaminants. The overall abatement rate of chemical oxygen demand (COD), ammonium nitrogen ( NH 4 + - N ), and salinity were 75.8%, 85.9%, and 75.13%, respectively. The bioremediation process resulted in up of 75% removal efficiency of Ni and Cd, and a 73.45%, 68.53%, and a 58.17% removal rates of Cu, Pb, and Fe, respectively. The research findings indicate the performance of L. lactis and K. marxianus co-culture isolated from kefir grains for the bioremediation of LFL. PRACTITIONER POINTS: Isolation and identification of microorganisms from kefir grains was carried out. Biological treatment of LFL using monoculture of (Lactoccocus lactis; Kluyveromyces marxianus) and co-culture (5% of L. lactis and 5% K. marxianus) has been performed. Biological treatment using co-culture strain is an effective approach to remove organic matter, NH 4 + - N and heavy metals.

PANI/TiO2 nanocomposite-based chemiresistive gas sensor for the detection of E. Coli bacteria

In the modern pace of the world, food safety is a major concern. In this work, a simple chemiresistive type gas sensor was fabricated to detect Escherichia Coli (E. coli) bacteria. Polyaniline (PANI) films were deposited on the indium tin oxide substrate by an electrochemical deposition method. TiO2 nanoparticles were synthesised by facile hydrothermal method. PANI films were modified using hydrothermally prepared TiO2 nanoparticles by a spin coating method. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and ultraviolet-visible spectrophotometer techniques were used to characterise the PANI/TiO2 nanocomposites. The peaks obtained in the XRD pattern confirmed the anatase phase of TiO2 nanoparticles. FESEM analysis showed the nanofibrous structure of the nanocomposite. The FTIR characteristic peaks confirmed the formation of the nanocomposite. The electrical resistance of the sensors was evaluated as a function of the bacterial concentration. The PT2 (TiO2 coated 5 times on PANI) in comparison with PT1 (TiO2 coated 3 times on PANI) exhibited good sensitivity to the gas molecules at room temperature. The p-n junction at PANI/TiO2 interface improved the physical adsorption of gas molecules. Since no specific antibodies or receptors are used, the sensor has the potential for adaptation to real-life applications. Thus low cost, real-time, portable, reusable and sensitive bacteria sensors were fabricated and tested.

Structural and physicochemical properties of Rheum emodi mediated Mg(OH)2 nanoparticles and their antibacterial and cytotoxic potential

In the present investigation, Rheum emodi roots extract mediated magnesium hydroxide nanoparticles [Mg(OH)2 NPs] through the bio-inspired experimental technique were synthesised. Mg(OH)2 NPs were characterised by using various characterisation techniques such as field emission scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy. The formation of Mg(OH)2 NPs was confirmed by X-ray diffraction. The structural analysis confirmed the hexagonal crystal symmetry of Mg(OH)2 NPs with space group P-3m1 and space group no. 164 using the Rietveld refinement technique. TEM micrographs illustrated the nano-size formation of Mg(OH)2 NPs of spherical shape and size ∼14.86 nm. With the aid of FTIR data, plant metabolites such as anthraquinones have been identified as a stabilising and reducing agent for the synthesis of biogenic Mg(OH)2 NPs. The synthesised Mg(OH)2 NPs showed antimicrobial and cytotoxic potential against Gram-negative and Gram-positive bacteria such as Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) and MDA-MB-231 human breast cancer cell lines.

Grape Pomace: A Potential Ingredient for the Human Diet

The industrial production of wine generates annually tons of waste that can and must be properly reused to reduce its polluting load ad increase the availability of passive ingredients to be used in human nutrition. Grape pomace, a by-product of winemaking, beyond being of nutritional value is a bioactive source with high potential value and benefits for human health. Having as main goal the preliminary perception of the potential use of this by-product, the aim of this study was the characterization of eight different grape pomaces. In this sense, ash content, relative ash, moisture, pH, microorganisms, metals (Al, Cd, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, and Zn), and semi-metal (As) were reported. The parameter that limits the daily amount ingested of this product is its arsenic content, a non-essential element that belongs to the group of semi-metal. Considering the obtained results and in the light of the restrictions imposed through the legislation in regulations set by the European Commission, the inclusion of grape pomace in the industrial production of foodstuffs could be a step towards the future of human nutrition and health.

Persistent Activities of Extracellular Enzymes Adsorbed to Soil Minerals

Adsorption of extracellular enzymes to soil minerals is assumed to protect them against degradation, while modifying their activities at the same time. However, the persistence of the activity of adsorbed enzymes remains poorly understood. Therefore, we studied the persistence of cellulase and α-amylase activities after adsorption to soil amended with various amounts (+1, +5, and +10 wt.%) of three typical soil minerals, montmorillonite, kaolinite, and goethite. Soil without mineral addition (pure soil), pure minerals, and pure dissolved enzymes were used as references. Soil mineral–enzyme complexes were prepared and then incubated for 100 days; temporal changes in enzyme activities were analyzed after 0, 0.1, 1, 10, and 100 days. The specific enzyme activities (activities normalized to protein content) and their persistence (activities relative to activities at day 0) were compared to enzyme activities in solution and after sorption to the control soil. Amylase adsorption to pure minerals increased in the following order: montmorillonite > kaolinite > goethite. That of cellulase increased in the following order: goethite > montmorillonite > kaolinite. Adsorption of enzymes to soils did not increase in the same order of magnitude as the addition of reactive binding sites. Based on inverse relationships between the amount of enzyme adsorbed and the specific enzyme activity and their persistency, we showed that a limited availability of sorption sites is important for high specific activity and persistence of the enzymes. This is probably the consequence of less and weaker bonds, as compared to a high availability of sorption sites, resulting in a smaller impact on the active sites of the enzyme. Hence, we suppose that the soil mineral phase supports microorganisms in less-sorptive environments by saving energy on enzyme production, since small enzyme release could already result in sufficient activities to degrade respective target carbon substrates.

Biotemplate-Mediated Green Synthesis and Applications of Nanomaterials

Green synthesis, an emerging field in bionanotechnology, refers to the utilization of non-toxic, biologically safe, and eco-friendly substances for the synthesis of desired materials. It provides both economic and environmental benefits along with simple, cost-effective, and reproducible synthesis approaches that result in the development of stable materials. The green synthesis approaches use living biotemplates, including plants and different microorganisms such as viruses, bacteria, fungi, algae, and actinomycetes. The various metabolites present in different parts of the plants, such as leaves, fruits, seeds, flower, and others, serve as the reducing and stabilizing agents. At the same time, the diverse surface chemistry of microorganisms enables them to convert different substrates into a variety of nanomaterials. This review briefly describes the concept of 'green synthesis' and provides an overview of controlled and green synthesis of nanomaterials using the plants and microbial cells as biotemplates. It also discusses the effect of different reaction conditions such as temperature, pH, reaction time, precursor concentration, and the post-synthesis processing of nanoparticles (NPs) on the material properties. It further describes the applications of different NPs in pharmaceutical and environment sectors by considering their diverse antimicrobial, anticancer, antioxidant, antiviral, antimalarial, reduction, and catalytic properties. Finally, it describes various future perspectives of nanomaterials to broaden the understanding of their synthesis mechanism and expand their applications to other fields.

Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium Pseudodesulfovibrio hydrargyri: Evidences From HERFD-XANES and Nano-XRF

Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 μM on the production and degradation of MeHg in two sulfate-reducing bacteria, Pseudodesulfovibrio hydrargyri BerOc1 able to methylate and demethylate mercury and Desulfovibrio desulfuricans G200 only able to demethylate MeHg. MeHg produced by BerOc1 increased with increasing IHg concentration with a maximum attained for 5 μM, and suggested a saturation of the process. MeHg was mainly found in the supernatant suggesting its export from the cell. Hg L₃-edge High- Energy-Resolution-Fluorescence-Detected-X-ray-Absorption-Near-Edge-Structure spectroscopy (HERFD-XANES) identified MeHg produced by BerOc1 as MeHg-cysteine₂ form. A dominant tetracoordinated βHgS form was detected for BerOc1 exposed to the lowest IHg concentrations where methylation was detected. In contrast, at the highest exposure (50 μM) where Hg methylation was abolished, Hg species drastically changed suggesting a role of Hg speciation in the production of MeHg. The tetracoordinated βHgS was likely present as nano-particles as suggested by transmission electron microscopy combined to X-ray energy dispersive spectroscopy (TEM-X-EDS) and nano-X ray fluorescence (nano-XRF). When exposed to MeHg, the production of IHg, on the contrary, increased with the increase of MeHg exposure until 50 μM for both BerOc1 and G200 strains, suggesting that demethylation did not require intact biological activity. The formed IHg species were identified as various tetracoordinated Hg-S forms. These results highlight the important role of thiol ligands and Hg coordination in Hg methylation and demethylation processes.

The aspects of microbial biomass use in the utilization of selected waste from the agro-food industry

Cellular biomass of microorganisms can be effectively used in the treatment of waste from various branches of the agro-food industry. Urbanization processes and economic development, which have been intensifying in recent decades, lead to the degradation of the natural environment. In the first half of the 20th century, problems related to waste management were not as serious and challenging as they are today. The present situation forces the use of modern technologies and the creation of innovative solutions for environmental protection. Waste of industrial origin are difficult to recycle and require a high financial outlay, while the organic waste of animal and plant origins, such as potato wastewater, whey, lignin, and cellulose, is dominant. In this article, we describe the possibilities of using microorganisms for the utilization of various waste products. A solution to reduce the costs of waste disposal is the use of yeast biomass. Management of waste products using yeast biomass has made it possible to generate new metabolites, such as β-glucans, vitamins, carotenoids, and enzymes, which have a wide range of industrial applications. Exploration and discovery of new areas of applications of yeast, fungal, and bacteria cells can lead to an increase in their effective use in many fields of biotechnology.

Extremophile Microbial Communities and Enzymes for Bioenergetic Application Based on Multi-Omics Tools

Abstract: Genomic and proteomic advances in extremophile microorganism studies are increasingly demonstrating their ability to produce a variety of enzymes capable of converting biomass into bioenergy. Such microorganisms are found in environments with nutritional restrictions, anaerobic environments, high salinity, varying pH conditions and extreme natural environments such as hydrothermal vents, soda lakes, and Antarctic sediments. As extremophile microorganisms and their enzymes are found in widely disparate locations, they generate new possibilities and opportunities to explore biotechnological prospecting, including biofuels (biogas, hydrogen and ethanol) with an aim toward using multi-omics tools that shed light on biotechnological breakthroughs.

Determination of the Empirical Electrokinetic Equilibrium Condition of Microorganisms in Microfluidic Devices

The increased concern regarding emerging pathogens and antibiotic resistance has drawn interest in the development of rapid and robust microfluidic techniques to analyze microorganisms. The novel parameter known as the electrokinetic equilibrium condition (EEEC) was presented in recent studies, providing an approach to analyze microparticles in microchannels employing unique electrokinetic (EK) signatures. While the EEEC shows great promise, current estimation approaches can be time-consuming or heavily user-dependent for accurate values. The present contribution aims to analyze existing approaches for estimating this parameter and modify the process into an accurate yet simple technique for estimating the EK behavior of microorganisms in insulator-based microfluidic devices. The technique presented here yields the parameter called the empirical electrokinetic equilibrium condition (eEEEC) which works well as a value for initial approximations of trapping conditions in insulator-based EK (iEK) microfluidic systems. A total of six types of microorganisms were analyzed in this study (three bacteria and three bacteriophages). The proposed approach estimated eEEEC values employing images of trapped microorganisms, yielding high reproducibility (SD 5.0–8.8%). Furthermore, stable trapping voltages (sTVs) were estimated from eEEEC values for distinct channel designs to test that this parameter is system-independent and good agreement was obtained when comparing estimated sTVs vs. experimental values (SD 0.3–19.6%). The encouraging results from this work were used to generate an EK library of data, available on our laboratory website. The data in this library can be used to design tailored iEK microfluidic devices for the analysis of microorganisms.