Search Results (190)

The persistence of antibiotics and antibiotic-resistant bacteria (ARB) in aquatic environments poses a significant risk to both the environment and public health. Conventional wastewater treatment systems are often inefficient in completely removing these emerging contaminants, highlighting the need for advanced and integrative treatment approaches. Electrocoagulation (EC) has emerged as a promising electrochemical method due to its operational simplicity, low chemical demand, and versatility in treating a wide range of wastewater types. This review critically analyzes the efficiency of EC, both as a standalone process and in combination with complementary technologies such as electrooxidation, membrane filtration, advanced oxidation processes (AOPs), and biological treatments. Emphasis is placed on the removal mechanisms, influencing parameters (pH, current density, electrode material), and the synergistic effects that enhance the degradation of antibiotics and the inactivation of ARB. Additionally, the review discusses the limitations of EC, including electrode passivation and energy consumption. The integration of EC with other technologies demonstrates improved pollutant removal and process robustness, offering a viable alternative for treating complex wastewater streams. This work provides a perspective on the current state and future potential of EC-based hybrid systems in mitigating the environmental impact of antibiotic pollutants and antimicrobial resistance. Full article

Aquatic environments are potential reservoirs for the persistence and spread of pathogenic bacteria. This study investigated the prevalence of Salmonella spp. in stream environments and their relationship with clinical isolates in Republic of Korea. A total of 4582 water samples were collected from 94 streams. We identified these isolates using MALDI–TOF MS and the Kauffmann–White scheme. Polymerase chain reaction and sequencing were performed to identify the resistance genes. Whole genome sequencing analysis and pulsed-field gel electrophoresis (PFGE) were performed to investigate genetic relatedness. In total, 110 Salmonella isolates showing 23 serotypes were isolated from the streams. S. Typhimurium (20.9%) was the most common, followed by S. Livingstone (17.3%), S. Infantis (10.9%), S. Othmarschen (6.4%), S. I. 4,[5],12:i:- (5.5%), and S. Thompson (5.5%). PFGE patterns of eight serotypes were identical or closely related to the stream and clinical strains. The sequence types of S. Mbandaka and S. Livingstone isolates from streams were identical to those of the clinical specimens as ST413 and ST543, respectively. Salmonella strains are highly prevalent in streams and are closely related to the isolates obtained from patients. Therefore, the continuous monitoring of stream environments is required to control the spread of Salmonella. Full article

Extremophilic biological process (EBP) pretreatment increases substrate availability in anaerobic digestion, but the effect on downstream microbial community composition in industrial systems is not characterized. Changes in microbial communities were determined at an industrial facility processing dairy manure in a modified split-stream system with three reactor types: (1) EBP tanks at 70–72 °C; (2) mesophilic Continuously Stirred Tank Reactors (CSTRs); (3) mesophilic Induced Bed Reactors (IBRs) receiving combined CSTR and EBP effluent. All reactors had a two-day hydraulic retention time. Samples were collected weekly for 60 days. pH, volatile fatty acid and bicarbonate concentrations, COD, and methane yield were measured to assess tank environmental conditions. Microbial community compositions were obtained via 16S rRNA gene sequencing. EBP pretreatment increased acetate availability but led to a decline in the relative abundance of acetoclastic Methanosarcina species in downstream IBRs. Rather, syntrophic methanogens, e.g., members of Methanobacteriaceae, increased in relative abundance and became central to microbial co-occurrence networks, particularly in association with hydrogen-producing bacteria. Network analysis also demonstrated that these syntrophic relationships were tightly coordinated in pretreated digestate but absent in the untreated CSTRs. By promoting syntrophic methanogenesis while increasing acetate concentrations, EBP pretreatment requires system configurations that enable acetoclast retention to prevent acetate underutilization and maximize methane yields. Full article

Disinfection by ultrasound and carbon nanotubes (CNTs) provides attractive alternatives to conventional methods for water and wastewater treatment. This study explored the inactivation of Escherichia coli (E. coli) by 5 mg/L pristine short and long multi-walled CNTs (MWCNTs) and 20 kHz ultrasound individually or in combinations in DI water, Suwannee River natural organic matter (SRNOM), and sodium dodecyl sulfate (SDS) solution, respectively. The results indicated that the dispersity of MWCNTs was the single most important factor determining the inactivation rate of E. coli. The dispersity of short MWCNTs in solutions increased in the order of DI water <10 mgC/L SRNOM < 2 mM SDS. Correspondingly, the greatest log inactivation of E. coli was achieved in SDS when short MWCNTs were used alone (0.67 ± 0.12) and combined with ultrasound (1.80 ± 0.02) for 10 min. Short MWCNTs alone had a slightly greater inactivation (0.29 ± 0.07) in SRNOM solution than in DI water (0.18 ± 0.05). However, long MWCNTs had a slightly higher inactivation in DI water (0.24 ± 0.03) than short ones (0.18 ± 0.05), because of better dispersity in DI. The observed synergistic inactivation when ultrasound and short MWCNTs were used together in 2 mM SDS shows that ultrasound energized the MWCNTs more effectively when they were well dispersed, although SDS and MWCNTs can occupy the reaction sites at the cavitational bubble–water interfacial regions and scavenge •OH radicals. The results suggest that sonophysical effects are more important to inactivate E. coli than sonochemical effects. Ultrasound inactivates E. coli and/or energizes MWCNTs through the mechanisms of acoustic streaming, microstreaming, microstreamers, transient cavitation collapse-generated shock waves and microjets (transitional forms), and localized hot temperatures. The results of this study indicate that the cytotoxicity of CNTs includes impinging bacterial cells and/or direct contact with the bacteria. Full article

With the global population steadily rising, the demand for sustainable protein sources has become increasingly urgent. Traditional animal- and plant-based proteins face challenges related to scalability, resource efficiency, and environmental impact. In this context, single-cell protein has emerged as a promising alternative. Derived from microorganisms such as algae, bacteria, fungi, and yeast, single-cell protein offers a high nutritional profile- including all essential amino acids and vitamins—while enabling rapid production, minimal land and water requirements, and no generation of greenhouse gas emissions. A particularly compelling advantage of single-cell protein is its ability to be produced from agro-industrial waste, converting low-cost residues into valuable nutritional resources and contributing to environmental sustainability. Among these waste streams, lignocellulosic biomass from agricultural and forestry residues stands out as a renewable, biodegradable, and abundant feedstock. This review explores the potential of lignocellulosic waste as a substrate for single-cell protein production, emphasizing both its environmental advantages and nutritional value. It highlights the single-cell protein role as a sustainable and scalable alternative to conventional protein sources. The review also identifies key scientific, economic, and regulatory challenges, and recognizes the importance of targeted investments, particularly in policy development, public awareness, and technological innovation, to enable the broader adoption and acceptance of single-cell protein -based products. Full article

The manipulation of cells and bioparticles has garnered significant interest in the field of viscoelastic microfluidics, particularly regarding its capacity for single-stream focusing within a three-dimensional and simple microchannel structure. The inherent simplicity of this method enables the effective manipulation of particles, facilitating the separation and focusing of various cell types, including blood cells, circulating tumor cells (CTCs), and microalgae. However, the viscoelastic nature of the particles imposes limitations in the handling of submicron-sized particles, due to a significant decrease in the viscoelastic force acting on the particle. In this study, we propose a microfluidic device featuring a cruciform cross-sectional microchannel with 45 µm and 45 µm of its vertical and horizontal size, respectively. The cruciform microchannel, which has a 270° reflex angle on four corners, can increase the viscoelastic force on the particles, allowing the device to focus submicron-sized particles down to 180 nm in a single-stream manner. It is important to note that the single-stream formation was maintained, while the channel width at the outlet region was drastically increased, allowing for the enrichment of submicron-sized particles. For biological feasibility, the proposed device also demonstrates the single-stream focusing on biological particles such as bacteria. The presented microfluidic device would have great potential for the focusing and enrichment of nanoparticles including bacteria in a highly robust manner, expecting its use in the various fields such as diverse biological analysis and biomedical research. Full article

Microorganisms metabolising low-value carbon sources can produce a diverse range of bio-based and biodegradable materials compatible with circular economy principles. One such material is bacterial cellulose (BC), which can be obtained in high purity through the fermentation of sweetened tea by a Symbiotic Culture of Bacteria and Yeast (SCOBY). In recent years, there has been a growing research interest in SCOBYs as a promising solution for sustainable material design. In this work, we have explored a novel method to grow SCOBYs vertically using a waste-based scaffold system. Waste sheep wool and cotton fabric were soaked in a SCOBY infusion to serve as scaffolds, carrying the infusion and facilitating vertical growth through capillary forces. Remarkably, vertical membrane growth up to 5 cm above the liquid–air interface (LAI) was observed after just one week. Membranes with different microstructures were found in sheep wool and cotton, randomly oriented between the scaffold fibre, resulting in a high surface area. This study demonstrated that vertical growth in scaffolds is possible, proving the concept of a new method of growing composite materials with potential high-value applications in biomedicine, energy storage, or filtration. Full article

Propionic acid (PA) is an important organic acid with applications in food preservation, feed additives, and bio-based chemical production. While industrial PA is mostly derived from petrochemical processes, sustainable microbial alternatives are gaining attention. In this study, we explored a co-fermentation strategy using lactic acid bacteria (LAB) with complementary metabolic capabilities to enhance PA biosynthesis via the 1,2-propanediol (PDO) pathway. Genome-based screening identified a metabolic division between strains capable of producing PDO (e.g., Carnobacterium maltaromaticum IBB3447) and those converting PDO to PA (e.g., Levilactobacillus brevis IBB3735). Notably, we discovered that C. maltaromaticum IBB3447 is capable of PDO 24 biosynthesis, a function previously undescribed in this species. Phenotypic assays confirmed glycerol metabolism and acid tolerance among strains. In co-culture fermentation trials, the highest PA concentration (6.87 mM) was achieved using simultaneous fermentation in a fructose–sorbitol–glucose (FRC-SOR-GLC) medium, accompanied by prior PDO accumulation (up to 13.13 mM). No single strain produced PA independently, confirming that metabolic cooperation is required. These findings reveal a novel LAB-based bioprocess for sustainable PA and PDO production, using cross-feeding interactions and the valorization of industrial waste streams. The study supports future optimization and scale-up for circular bioeconomy applications. Full article

Purple phototrophic bacteria (PPB) offer a sustainable approach for biological wastewater treatment while simultaneously producing valuable by-products such as polyhydroxyalkanoates (PHAs). This study investigates the effects of continuous light wavelengths over a two-stage nutrient reduction setup on PHA accumulation in a mixed PPB culture grown on fuel synthesis wastewater (FSW). The first stage promoted biomass production under nutrient availability, while the second stage targeted the enhancement of PHA accumulation through nitrogen (N) or phosphorus (P) reduction. Biomass growth remained stable under P reduction but significantly increased under N reduction. The results showed that organics removal efficiency decreased under nutrient reduction, particularly under P reduction, while N reduction conditions enhanced P uptake from the media. Maximum PHA accumulation reached 12.6% CDW under N reduction and 10.0% CDW under P reduction. Light type played a dominant role, with a full-spectrum light that included ultraviolet (UV) and infrared (IR) promoting the highest PHA accumulation, whereas white light with far-red wavelengths (700–770 nm) enhanced biomass growth. These findings highlight the potential of optimizing light conditions and nutrient availability to enhance PHA biosynthesis, paving the way for improved bioplastic production from wastewater streams. Full article

Anaerobic ammonium oxidation (anammox) technologies have attracted substantial interest due to their advantages over traditional biological nitrogen removal processes, including high efficiency and low energy demand. Currently, multiple side-stream applications of the anammox coupling process have been developed, including one-stage, two-stage, and three-stage systems such as completely autotrophic nitrogen removal over nitrite, denitrifying ammonium oxidation, simultaneous nitrogen and phosphorus removal, partial denitrification-anammox, and partial nitrification and integrated fermentation denitritation. The one-stage system includes completely autotrophic nitrogen removal over nitrite, oxygen-limited autotrophic nitrification/denitrification, aerobic de-ammonification, single-stage nitrogen removal using anammox, and partial nitritation. Two-stage systems, such as the single reactor system for high-activity ammonium removal over nitrite, integrated fixed-film activated sludge, and simultaneous nitrogen and phosphorus removal, have also been developed. Three-stage systems comprise partial nitrification anammox, partial denitrification anammox, simultaneous ammonium oxidation denitrification, and partial nitrification and integrated fermentation denitritation. The performance of these systems is highly dependent on interactions between functional microbial communities, physiochemical parameters, and environmental factors. Mainstream applications are not well developed and require further research and development. Mainstream applications demand a high carbon/nitrogen ratio to maintain levels of nitrite-oxidizing bacteria, high concentrations of ammonium and nitrite in wastewater, and retention of anammox bacteria biomass. To summarize various aspects of the anammox processes, this review provides information regarding the microbial diversity of different genera of anammox bacteria and the engineering aspects of various side streams and mainstream anammox processes for wastewater treatment. Additionally, this review offers detailed insights into the challenges related to anammox technology and delivers solutions for future sustainable research. Full article

Microbial fuel cells (MFCs) are environmentally friendly energy converters that use electrochemically active bacteria (EAB) as catalysts to break down organic matter while producing bioelectricity. Traditionally, MFC research has relied on simple organic substrates, such as acetate, glucose, sucrose, butyrate, and glutamate, the production of which involves energy-intensive, CO₂-dependent processes and chemically aggressive methods. In contrast, nonconventional waste streams offer a more sustainable alternative as feedstocks, aligning with zero-waste and regenerative agricultural principles. This review highlights the potential of nonconventional organic wastes, such as fruit and vegetable wastes, raw human and livestock urine, and farm manure, as globally available and low-cost substrates for MFCs, particularly in household and farming applications at small-scale waste levels. Furthermore, complex waste sources, including hydrocarbon-contaminated effluents and lignin-rich industrial wood waste, which present unique challenges and opportunities for their integration into MFC systems, were examined in depth. The findings of this review reveal that MFCs utilizing nonconventional substrates can achieve power outputs comparable to traditional substrates (e.g., 8314 mW m⁻²–25,195 mW m⁻² for crude sugarcane effluent and raw distillery effluent, respectively) and even superior to them, reaching up to 88,990 mW m⁻² in MFCs utilizing vegetable waste. Additionally, MFCs utilizing hydrocarbon-containing petroleum sediment achieved one of the highest reported maximum power densities of 50,570 mW m⁻². By integrating diverse organic waste streams, MFCs can contribute to carbon-neutral energy generation and sustainable waste management practices. Full article

Lactic acid (LA) is a key chemical used in various industries, including food, pharmaceuticals, and bioplastics. Although traditionally produced using lactic acid bacteria, yeasts offer significant advantages, such as higher tolerance to acidic environments, a broader substrate range, and the potential for genetic and metabolic engineering. This review explores the potential use of Lachancea thermotolerans, Saccharomyces cerevisiae, Kluyveromyces marxianus, Kluyveromyces lactis, Candida utilis, and Pichia kudriavzevii as LA producers, highlighting their unique characteristics and industrial applications. S. cerevisiae stands out due to its robust genetic toolkit and acid tolerance, while K. marxianus offers thermotolerance and the efficient utilization of lactose and pentoses, making it ideal for high-temperature fermentations. K. lactis is particularly suited for valorizing dairy by-products like whey, P. kudriavzevii exhibits high tolerance to multiple stresses, while C. utilis demonstrates superior resilience to lignocellulosic inhibitors, enabling its use in biorefineries. Key challenges, including enhancing LA tolerance and optimizing metabolic pathways, are addressed through strategies like heterologous lactate dehydrogenase (LDH) expression, redox balance modification, and adaptive laboratory evolution. The review also discusses industrial applications, particularly in the context of circular economy approaches, where yeasts can convert waste streams into high-value LA. Future research should focus on integrating yeasts into scalable, sustainable bioprocesses to meet the growing demand for renewable and biodegradable materials. Full article

The effects of medium and flow rate on the film-forming structures of B10 Cu-Ni alloys and their resistance to corrosion caused by sulfate-reducing bacteria are investigated in this article. Combined with a predicted cloud map of pipeline corrosion area and a particle motion trajectory map obtained using Computational Fluid Dynamics (CFD), the growth law of alloy passivation films was analyzed and the pitting process of sulfate-reducing bacteria (SRB) on passivation films was revealed. The results show that the film formation effect is best when the stream of water in the film-forming environment is filtered seawater with a flow rate of 0.8 m/s, which consists of a uniform and dense gray-brown passivated film layer with the strongest resistance to SRB corrosion. When the flow rate is 0 m/s, the clay particles in the seawater cover the surface of the passivation film, hindering the contact of oxygen with the substrate and inhibiting the growth of the passivation film. When the stream of water in the film-forming environment is seawater with a flow rate of 3 m/s, the surface of the substrate shows obvious scouring marks, which is favorable for the enrichment of SRB and further accelerates the pitting corrosion of the substrate. Cl⁻ has a significant influence on the formation of passivation films on B10 Cu-Ni alloys. When the filming medium is deionized water, the B10 Cu-Ni alloy does not form a complete passivation film at all flow rates. Full article

The biogas and biomethane sectors are crucial for the European Union’s energy transition. One strategy for achieving the EU’s biogas and biomethane targets while reducing the use of agricultural land for energy feedstock production is to use alternative biomass streams. Such a stream includes agricultural residues and by-products. A good example is crop residues after harvesting corn for grain, which are available in large quantities. Due to the fact that they are lignocellulosic biomasses, they require pretreatment. The purpose of this study was to determine the effect of ensiling enhancers on the methane yield of corn stover silages. Corn stover, which was harvested using the same technology, was ensiled in the first variant with an ensiling enhancer preparation based on bacteria of the Lactobacillus plantarum strain (DSM 3676 and DSM 3677) and two strains of propionic acid bacteria (DSM 9676 and DSM 9677), in the second variant with a formulation whose active ingredients were sodium benzoate, propionic acid, and sodium propionite, and in the third with a formulation based on lactic acid bacteria of the strain Lactobacillus plantarum and Lactobacillus Buchneri. The fourth variant was the control; that is, the material was ensiled naturally without the ensiling enhancer preparation. The use of the ensiling enhancer, based on lactic acid bacteria of the Lactobacillus plantarum and Lactobacillus Buchneri strains, reduced carbon dioxide emissions per 1 GJ of silage energy potential in the biogas production process. Specifically, the unique contribution of this research lies in demonstrating the role of ensiling enhancers in improving methane yield and reducing carbon dioxide emissions. Full article

Background: Empirical antibacterial therapy for febrile neutropenia reduces mortality due to Gram-negative blood stream infections (BSIs). Pediatric guidelines recommend monotherapy with an antipseudomonal beta-lactam or a carbapenem and to add a second anti-Gram-negative agent in selected situations. We evaluated the changes in the proportions of resistance of beta-lactam monotherapies vs. their combination with amikacin, and the possible impact on ICU admission or death. Results: 797 BSIs due to Gram-negative bacteria in 685 patients were included. Combination therapies with amikacin had a lower percentage of isolates resistant to one or to both drugs compared with the respective monotherapy. The highest OR for ICU admission was observed when both drugs of the combination of meropenem–amikacin were resistant. Mortality was significantly associated with relapse or the progression of the underlying malignancy, and resistance to both drugs of the combinations of cefepime–amikacin or meropenem–amikacin. Methods: This study was based on data collected for a large multinational study, in which the susceptibility of Gram-negative bloodstream isolates was categorized following either EUCAST or CLSI according to local laboratory standards. An escalation antibiogram was generated for each selected drug. For resistant bacteria, the conditional susceptibility probability on resistance was calculated. Conclusions: In pediatric cancer patients with Gram-negative BSIs, the proportion of the resistant organism correlates with ICU admission or death, which may be reduced by combination therapy. In patients with suspected or confirmed Gram-negative BSIs that are not-improving or deteriorating under monotherapy, escalation to meropenem may represent the best option. Amikacin should be preferred when combination therapy is considered with ciprofloxacin as an alternative in the case of impaired renal function. Full article