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Abstract The self-healing of concrete through the use of bacteria is an ecological, sustainable, and environmentally friendly method that can replace time-consuming and costly repairs. The aim of this research was to isolate and select spore-forming bacilli with potential for concrete self-healing. Soil samples from the limestone mines of Simbal, Trujillo, La Libertad, Peru were used. These samples were processed to primarily isolate spore-forming bacteria. The self-healing potential of these bacteria was evaluated through their ability to produce the urease enzyme, grow at an alkaline pH, and produce calcium carbonate crystals in a culture medium with urea and CaCl2 at pH 8.0. The produced crystals were visualized with scanning electron microscopy and their calcium content was confirmed through EDS analysis. The isolated bacteria were identified by 16 S rRNA gene amplification by PCR as Bacillus sp and Streptomyces sp. It was observed that Bacillus sp. produces CaCO3 crystals with vaterite morphology, while Streptomyces sp. produces rhombohedral calcite crystals. It is concluded that the isolated bacteria have the potential to be used in concrete self-healing processes.

Nowadays, there is great interest in microbial fuel cells because of the different substrates that can be used in them for electric energy generation. In order to find an alternative and contribute with eco-friendly technologies, this research used the Serratia fonticola bacteria and Rhotula glutinis yeast as a fuel source through laboratory scale microbial fuel cells. A single chamber microbial fuel cell with air cathode was fabricated with a copper foil and a graphite plate as anode and cathode electrode respectively. For the characterization of the cells, physicochemical parameters such as voltage, electric current, pH and electrical conductivity were measured for 30 days and at room temperature (18 ± 2.2 °C). It was possible to generate peak voltage and current values of 0.53 ± 0.01 V and 0.55 ± 0.02 V and current values of 1.76 ± 0.16 mA and 1.52 ± 0.02 mA, for MFCs with bacteria and yeast respectively. In addition, acidic operating pH was observed, and its conductivity peak values around 242 mS/cm. Finally, this work demonstrates the great potential that microorganisms have for the generation of electric current, giving a new and promising way to generate electricity

The growing demand for agricultural products has increased exponentially, causing their waste to increase and become a problem for society. Searching for sustainable solutions for organic waste management is increasingly urgent. This research focuses on considering the waste of an Andean tuber, such as Olluco, as a fuel source for generating electricity and becoming a potential sustainable energy source for companies dedicated to this area. This research used Olluco waste as fuel in single-chamber microbial fuel cells using carbon and zinc electrodes. An electric current and electric potential of 6.4 ± 0.4 mA and 0.99 ± 0.09 V were generated, operating with an electrical conductivity of 142.3 ± 6.1 mS/cm and a pH of 7.1 ± 0.2. It was possible to obtain a 94% decrease in COD and an internal resistance of 24.9 ± 2.8 Ω. The power density found was 373.8 ± 28.8 mW/cm2 and the current density was 4.96 A/cm2. On day 14, the cells were connected in earnest, achieving a power of 2.92 V and generating enough current to light an LED light bulb, thus demonstrating the potential that Olluco waste has to be used as fuel in microbial fuel cells.

Currently, industry in all its forms is vital for the human population because it provides the services and goods necessary to live. However, this process also pollutes soils and rivers. This research provides an environmentally friendly solution for the generation of electrical energy and the bioremediation of heavy metals such as arsenic, iron, and copper present in river waters used to irrigate farmers’ crops. This research used single-chamber microbial fuel cells with activated carbon and zinc electrodes as anodes and cathodes, respectively, and farmers’ irrigation water contaminated with mining waste as substrate. Pseudomonas stutzeri was used as a biocatalyst due to its ability to proliferate at temperatures between 4 and 44 °C—at which the waters that feed irrigated rivers pass on their way to the sea—managing to generate peaks of electric current and voltage of 4.35 mA and 0.91 V on the sixth day, which operated with an electrical conductivity of 222 mS/cm and a pH of 6.74. Likewise, the parameters of nitrogen, total organic carbon, carbon lost on the ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 51.19%, 79.92%, 64.95%, 79.89%, 79.93%, and 86.46%. At the same time, iron, copper, and arsenic values decreased by 84.625, 14.533, and 90.831%, respectively. The internal resistance values shown were 26.355 ± 4.528 Ω with a power density of 422.054 mW/cm2 with a current density of 5.766 A/cm2. This research gives society, governments, and private companies an economical and easily scalable prototype capable of simultaneously generating electrical energy and removing heavy metals.

The great utility that plastics generate for society has generated a large amount of waste, producing tons of garbage from this material that damages the ecosystem, human health, and farmland. Likewise, the issue of the absence of electricity in low-income areas is critical for society. This research proposes a novel solution to simultaneously solve these two problems, which, through single-chamber microbial fuel cells, introduce plastic waste and the fungus Paecilomyces. The microbial fuel cells (MFCs) showed a maximum electric current of 0.547 ± 0.185 mA with a peak voltage of 0.575 ± 0.106 V on day 36; on this day, the MFCs operated with a pH of 6.524 ± 0.360 and electrical conductivity of 264.847 ± 6.395 mS/cm. These results demonstrate the potential of this system to generate electricity from plastic waste, addressing the issue of electricity scarcity in low-income areas. The chemical oxygen demand was also reduced by 85.47%, indicating the system's ability to degrade plastic waste. The power density calculated on day 36 was 0.0624 ± 0.0053 mW/cm2 at a current density of 0.0052 mA/cm2 and an internal resistance of 55.254 ± 7.583 Ω. The reducing action of the fungus on the plastic was demonstrated in the FTIR transmittance spectrum because the characteristic peaks (3378, 2854–2911, 1642, 1472, and 720 cm−1) of the plastic suffered reductions in the final state, and the micrographs of the plastic surfaces showed the lifting of layers and the formation of irregular structures and a decrease in the thickness of the plastic sample of 139.66 ± 4.19 µm. [ABSTRACT FROM AUTHOR]

The mismanagement of plastic waste, organic waste, and the shortage of electricity in remote villages has created significant challenges for industries and governments. Therefore, this research aims to utilize the fungus Trichoderma sp. as a catalyst in microbial fuel cells, where the novelty of the research is the generation of electricity and the degradation of plastic simultaneously. In this study, single-chamber microbial fuel cells were constructed using carbon (anode) and zinc (cathode) electrodes. The substrate consisted of 20 gr of potato waste and 1.5 × 1.5 cm samples of plastic waste, all combined in 390 mL of Bushnell broth, into which Trichoderma sp. was inoculated. The highest electrical readings were recorded on day 23, showing values of 5.648 ± 0.093 mA and 0.479 ± 0.025 V. On the same day, the pH level was measured at 7.046 ± 0.314, and the substrate's electrical conductivity was found to be 155.135 ± 2.569 mS/cm. Over the 45-day monitoring period, the chemical oxygen demand decreased by 78.67%. The microbial fuel cells achieved a maximum power density of 68.140 ± 2.418 mW/cm2 at a current density of 4.719 mA/cm2, with an internal resistance of 23.647 ± 1.514 Ω. Analysis of the plastic using FTIR (Fourier Transform Infrared Spectroscopy) revealed a decrease in the intensity of spectral bands associated with hydroxyl groups, C-H structural groups, methyl groups, and C=C bonds. Additionally, SEM (Scanning Electron Microscopy) images demonstrated a reduction in the thickness of the plastic film and the formation of voids and sheets, highlighting the potential of Trichoderma sp. for plastic degradation. [ABSTRACT FROM AUTHOR]

Background and Objectives: In Peru, the presence of antimicrobial-resistant bacteria is a constant concern in hospitals and has likely increased in frequency during the pandemic. The objective of the study was to analyze the frequency of carbapenemase-producing bacteria resistant to two carbapenems (Imipenem and Meropenem), which were isolated from Peruvian patients in the intensive care unit of the Victor Lazarte Echegaray Hospital in Trujillo (Peru) during the COVID-19 pandemic. Materials and Methods: The biological samples of the patients hospitalized in the ICU were processed in the Microbiology Diagnostic Laboratory of the Víctor Lazarte Echegaray Hospital between May 2021 and March 2022. Antimicrobial sensitivity was determined with the automated system AutoScan-4, and for the identification of the type of carbapenemase, the RESISIT-3 O.K.N K-SET cassettes were used. Results: The results show that 76 cultures (76/129) had resistance to the two carbapenems (imipenem or meropenem), where the most frequent were Klebsiella pneuomoniae (31.6%), Pseudomonas aeruginosa (26.3%), and Acinetobacter baumannii (14.5%). Pseudomonas aeruginosa cultures showed at least three carbapenemase types (KPC, NDM, and OXA-48), while A. baumannii, Escherichia coli, and Burkholderia cepacia complex presented at least two carbapenemases (NDM and OXA-48). The carbapenemase NDM was detected in Enterobacter cloacae, Morganella morganii, and Proteus mirabilis, while KPC was present in all Klebsiella pneumoniae and Klebsiella oxytoca cultures. Conclusions: The samples from patients hospitalized in the Victor Lazarte Echegaray Hospital ICU showed a high prevalence of imipenem- and meropenem-resistant bacteria. These findings are relevant and concerning from the perspective of antibiotic-resistant bacteria monitoring, control, and disinfection. Thus, an appropriate antibiotic policy must be implemented.

This research aimed to use kiwi waste as fuel to generate bioelectricity through microbial fuel cells. It was possible to generate an electrical current and voltage peaks of 3.807 ± 0.102 mA and 0.993 ± 0.061 V on day 11, showing an electrical conductivity of 189.82 ± 3.029 mS/cm and an optimum operating pH of 5.966 ± 0.121. The internal resistance of the cells was calculated using Ohm’s Law, resulting in a value of 14.957 ± 0.394 Ω, while the maximum power density was 212.68 ± 26.84 mW/m2 at a current density of 4.506 A/cm2. Through the analysis of the FTIR spectra carried out on the substrate, a decrease in the characteristic organic peaks was observed due to their decomposition during the electricity-generation process. In addition, it was possible to molecularly identify the bacteria Comamonas testosteroni, Sphingobacterium sp., and Stenotropho-monas maltophila adhered to the anodized biofilm. Finally, the capacity of this residue to generate bioelectricity was demonstrated by lighting an LED bulb with a voltage of 2.85 V.

Plastic waste, a persistent and escalating issue, and the high costs of installing electric power, particularly in remote areas, have become pressing concerns for governments. This research proposes a novel method for generating electric power from sugarcane bagasse waste and reducing plastic waste. The key to this method is the use of the fungus Pleurotus ostreatus in microbial fuel cells. Microbial fuel cells (MFCs) demonstrated their effectiveness by generating peaks of electric current (4.325 ± 0.261 mA) and voltage (0.427 ± 0.031 V) on day twenty-six, with a pH of 5.539 ± 0.278. The peak electrical conductivity of the substrate was 130.574 ± 4.981 mS/cm. The MFCs were able to reduce the chemical oxygen demand by 83%, showing a maximum power density of 86.316 ± 4.724 mW/cm2 and an internal resistance of 37.384 ± 62.522 Ω. The infrared spectra of the plastic samples showed a decrease in the peaks 2850–2920, 1470, and 720 cm−1, which are more characteristic of plastic, demonstrating the action of the Pleurotus ostreatus fungus on the plastic samples. Also, the micrographs taken by SEM showed the reduction in the thickness of the plastic film by 54.06 µm and the formation of microstructures on the surface, such as pores and raised layers of the sample used. [ABSTRACT FROM AUTHOR]

The amount of waste from agriculture has significantly increased in recent decades due to the growing demand for food. Meanwhile, providing electricity to remote areas remains a challenge due to the high installation costs. Single-chamber fuel cells offer a promising solution as they can effectively generate electric power and treat organic waste. For this reason, the main objective of this research is to utilize pickled chili waste as fuel in SC-MFCs (single-chamber fuel cells), using carbon and zinc electrodes to assess its potential as a sustainable alternative fuel source. The fuel cells exhibited a maximum electric current and voltage of 5.565 ± 0.182 mA with 0.963 ± 0.033 V of voltage, respectively, with a substrate electrical conductivity of 113.526 ± 6.154 mS/cm with a pH of 6.62 ± 0.42 on the twelfth day. The internal resistance measured was 46.582 ± 6.845 Ω, and the maximum power density reached 148.128 ± 8.914 mW/cm2 at a current density of 3.657 A/cm2. Additionally, the microorganisms Pseudomonas taiwanensis and Candida parapsilosis were identified with 100% identity in the anode electrode. This study demonstrates that pickled chili residues can successfully generate bioelectricity and light an LED bulb connected to MFCs in series with a voltage of 2.67 V. [ABSTRACT FROM AUTHOR]

Industrialization has brought many environmental problems since its expansion, including heavy metal contamination in water used for agricultural irrigation. This research uses microbial fuel cell technology to generate bioelectricity and remove arsenic, copper, and iron, using contaminated agricultural water as a substrate and Bacillus marisflavi as a biocatalyst. The results obtained for electrical potential and current were 0.798 V and 3.519 mA, respectively, on the sixth day of operation and the pH value was 6.54 with an EC equal to 198.72 mS/cm, with a removal of 99.08, 56.08, and 91.39% of the concentrations of As, Cu, and Fe, respectively, obtained in 72 h. Likewise, total nitrogen concentrations, organic carbon, loss on ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 69.047, 86.922, 85.378, 88.458, and 90.771%, respectively. At the same time, the PDMAX shown was 376.20 ± 15.478 mW/cm2, with a calculated internal resistance of 42.550 ± 12.353 Ω. This technique presents an essential advance in overcoming existing technical barriers because the engineered microbial fuel cells are accessible and scalable. It will generate important value by naturally reducing toxic metals and electrical energy, producing electric currents in a sustainable and affordable way. [ABSTRACT FROM AUTHOR]

Currently, two significant problems involve the government, population, and environment: the accelerated increase in organic waste and the need to replace conventional energy with environmentally sustainable energy. The sustainable use of organic waste is being intensely investigated to generate energy plants that produce alternative sustainable electrical energy beneficial to the population at a low cost. The novelty of this research is given by the use of pepper waste as fuel in the generation of bioelectricity, giving added value to these types of waste, benefiting farmers and companies dedicated to the export and import of these fruits, because they will be able to generate their own electrical energy using their own waste at a lower cost. For this reason, this research uses pepper waste as fuel in single-chamber microbial fuel cells manufactured at a low cost as its primary objective. The maximum values of the electric current (5.118 ± 0.065 mA) and electric potential (1.018 ± 0.101 V) were shown on the fourteenth day, with an optimal operating pH of 7.141 ± 0.134 and electrical conductivity of 112.846 ± 4.888 mS/cm. Likewise, a reduction in the COD was observed from 1210.15 ± 0.89 mg/L to 190.36 ± 16.58 mg/L in the 35 days of monitoring and with a maximum ORP of 426.995 ± 8.615 mV, whose internal resistance was 33.541 ± 2.471 Ω. The peak power density was 154.142 ± 8.151 mW/cm2 at a current density of 4.834 A/cm2, and the Rossellomorea marisflavi strain was identified with 99.57% identity. [ABSTRACT FROM AUTHOR]