Interspecies microbial interactions in bioelectrochemical system and biodegradation: A state of the art review.

Microbial mutualistic interaction or synthetic microbiology evolves closely from the concept of cell-cell relations in a complex microbial community, which plays a crucial role in waste degradation, bioremediation, and bioenergy generation. Recently, the application of synthetic microbial consortia has renewed attention in the field of bioelectrochemistry. In the past few years, the influence of microbial mutualistic interaction has been extensively studied in bioelectrochemical systems (BES), especially in microbial fuel cells (MFCs). Nevertheless, synthetic microbial consortia were found to exhibit superior bioremediation performance compared to single strains of microbes for polycyclic aromatic hydrocarbons, synthetic dyes, polychlorinated biphenyls, and other organic pollutants compared to the respective single microbial species. However, a comprehensive understanding of intermicrobial interactions, specifically the metabolic pathways in a mixed-cultured microbial community system, is still lacking. In this study, we have comprehensively reviewed the possible pathways for executing intermicrobial communication within a complex microbial community consortium with various underlying pathways. The influence of mutualistic interactions on the power generation of MFCs and wastewater biodegradation has been widely reviewed. We argue that this study would motivate the design and construction of potential synthetic microbial consortia to stimulate the extraction of bioelectricity and the biodegradation of contaminants.

A novel atropine electrochemical sensor based on silver nano particle-coated Spirulina platensis multicellular blue-green microalga.

In this work, Atropine as the anticholinergic drug was measured using the environmentally friendly sensor. In this regard, Self-cultivated Spirulina platensis with electroless silver was employed as a powder amplifier in carbon paste electrode modification. Also, 1-Hexyl-3 methylimidazolium Hexafluorophosphate (HMIM PF6) ion liquid as a conductor binder was used in the suggested electrode construction. Atropine determination was investigated by voltammetry methods. According to voltammograms, the electrochemical behavior of atropine depends on pH, and pH 10.0 was used as the optimal condition. Moreover, the diffusion control process for the electro-oxidation of atropine was verified by the scan rate study, so the diffusion coefficient (D∼ 3.0136×10-4cm2/sec) value was computed from the chronoamperometry study. Furthermore, responses of the fabricated sensor were linear in the concentration range from 0.01 to 800 µM, and the lowest detection limit of the Atropine determination was obtained at 5 nM. Moreover, the stability, reproducibility, and selectivity factors of the suggested sensor were confirmed by the results. Finally, the recovery percentages for atropine sulfate ampoule (94.48-101.58), and water (98.01-101.3) approve of the applicability of the proposed sensor to Atropine determination in real samples.

Synthesis of N-myristoyltaurine stabilized gold and silver nanoparticles: Assessment of their catalytic activity, antimicrobial effectiveness and toxicity in zebrafish.

In this paper, the application of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) synthesized using a biomimetic lipid, N-myristoyltaurine (N14T) was evaluated in common fields. The catalytic effectiveness of AgNPs and AuNPs was studied in the popular nanocatalyst reaction, nitroaromatic reduction, and dye degradation. Both NPs display catalytic activity in the nitroaromatic compound and organic dyes reduction reaction involving sodium borohydride and the rate constant is estimated as 10-3 s-1. Strikingly, the reaction initiation time (t0) and completion time (tc) differ significantly between AgNPs and AuNPs. Analyzing the reaction kinetic profile revealed that the reaction carried out with AuNPs showed a shorter t0 and tc, suggesting a better catalyst than AgNPs. In addition, the efficiency of the NPs was examined in Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa). In difference to the catalytic study, AuNPs display poor antibacterial activity. Whereas AgNPs kill the tested bacteria at 250 µM via disturbing bacterial membrane integrity and produce excess reactive oxygen species. The toxicology study carried out with zebrafish animal model reveals that both AgNPs and AuNPs are non-toxic. The findings suggest that each nanomaterial possesses unique physicochemical properties irrespective of stabilization with the same molecules.

Evaluation of cytotoxicity and genotoxicity effects of refractory pollutants of untreated and biomethanated distillery effluent using Allium cepa.

Environmental pollution caused by the discharge of raw and partly treated distillery effluent has become a serious and threatening problem due to its high pollution load. The aim of the present study was to assess the physicochemical load in alcohol distillery effluent before and after biomethanation treatment and the cyto- and genotoxicity effects of refractory pollutants emanated in raw/untreated and biomethanated distillery effluent on the ultrastructural and biochemical responses of Allium cepa root tip cells. Physicochemical analysis revealed high biochemical oxygen demand (BOD: 47840-36651 mg L-1), chemical oxygen demand (COD: 93452-84500 mg L-1) and total dissolved solids (TDS: 64251-74652 mg L-1) in raw and biomethanated effluent along with metal(loid)s (Fe: 456.152-346.26; Zn: 1.654-1.465; Cu: 0.648-0.562; Ni: 1.012-0.951, and Pb: 0.264 mg L-1) which were beyond the safe discharge values prescribed by the environmental regulatory agencies. The UV-Visible and Fourier transform infrared spectrophotometry analyses confirmed the high levels of organic, inorganic, and mixed contaminants discharged in raw and biomethanated distillery effluents. Furthermore, GC-MS analysis characterised chemical contaminants, such as hexadecanoic acid, butanedioic acid, bis(trimethylsilyl) ester; hexadecane, 2,6,11,15-tetramethyl, stigmasterol, and ß-sitosterol trimethylsilyl ether that have been reported as androgenic-mutagenic, and endocrine disrupting chemicals by the United States Environmental Protection Agency (U.S. EPA). The cytotoxicity measured by A. cepa showed dose depended inhibition root growth inhibition and simultaneous reduction in mitotic index in tested effluents. The chromosomal aberrations studies resulted in laggard chromosomes, sticky chromosomes, vagrant chromosomes, chromosome loss, c-mitosis, chromosome bridge, abnormal metaphase, and disturbed anaphase as found in a dose-dependent manner. Furthermore, dose-dependent enhancement in the levels of malondialdehyde, hydrogen peroxide, and antioxidative enzymes, such as superoxide dismutase, ascorbate peroxidase, and catalase were found to be higher in raw effluents treated root cells compared to biomethanated distillery effluent. Analysis of ultrastructural changes in root tip cells by TEM analysis revealed dramatic changes in the morphology of cell organelles and accumulation of metallic elements in and on the surface tissues. The results concluded that the discharged distillery effluents retained certain toxic pollutants which imposed cytotoxic and genotoxic hazards to A. cepa. Thus, for the sake of environmental protection, the raw as well as the disposed biomethanated effluent must be efficiently treated before its dumping into the terrestrial ecosystem.

Selective Detection of Legionella pneumophila Serogroup 1 and 5 with a Digital Photocorrosion Biosensor Using Antimicrobial Peptide-Antibody Sandwich Strategy.

Rapid detection of Legionella pneumophila (L. pneumophila) is important for monitoring the presence of these bacteria in water sources and preventing the transmission of the Legionnaires' disease. We report improved biosensing of L. pneumophila with a digital photocorrosion (DIP) biosensor functionalized with an innovative structure of cysteine-modified warnericin antimicrobial peptides for capturing bacteria that are subsequently decorated with anti-L. pneumophila polyclonal antibodies (pAbs). The application of peptides for the operation of a biosensing device was enabled by the higher bacterial-capture efficiency of peptides compared to other traditional ligands, such as those based on antibodies or aptamers. At the same time, the significantly stronger affinity of pAbs decorating the L. pneumophila serogroup-1 (SG-1) compared to serogroup-5 (SG-5) allowed for the selective detection of L. pneumophila SG-1 at 50 CFU/mL. The results suggest that the attractive sensitivity of the investigated sandwich method is related to the flow of an extra electric charge between the pAb and a charge-sensing DIP biosensor. The method has the potential to offer highly specific and sensitive detection of L. pneumophila as well as other pathogenic bacteria and viruses.

Antimicrobial peptides: Promising alternatives over conventional capture ligands for biosensor-based detection of pathogenic bacteria.

The detection of pathogenic bacteria using biosensing techniques could be a potential alternative to traditional culture based methods. However, the low specificity and sensitivity of conventional biosensors, critically related to the choice of bio-recognition elements, limit their practical applicability. Mammalian antibodies have been widely investigated as biorecognition ligands due to high specificity and technological advancement in antibody production. However, antibody-based biosensors are not considered as an efficient approach due to the batch-to-batch inconsistencies as well as low stability. In recent years, antimicrobial peptides (AMPs) have been increasingly investigated as ligands as they have demonstrated high stability and possessed multiple sites for capturing bacteria. The conjugation of chemo-selective groups with AMPs has allowed effective immobilization of peptides on biosensor surface. However, the specificity of AMPs is a major concern for consideration as an efficient ligand. In this article, we have reviewed the advances and concerns, particularly the selectivity of AMPs for specific detection of pathogenic bacteria. This review also focuses the state-of-the-art mechanisms, challenges and prospects for designing potential AMP conjugated biosensors. The application of AMP in different biosensing transducers such as electrochemical, optical and piezoelectric varieties has been widely discussed. We argue that this review would provide insights to design and construct AMP conjugated biosensors for the pathogenic bacteria detection.

Use of Industrial Wastes as Sustainable Nutrient Sources for Bacterial Cellulose (BC) Production: Mechanism, Advances, and Future Perspectives.

A novel nanomaterial, bacterial cellulose (BC), has become noteworthy recently due to its better physicochemical properties and biodegradability, which are desirable for various applications. Since cost is a significant limitation in the production of cellulose, current efforts are focused on the use of industrial waste as a cost-effective substrate for the synthesis of BC or microbial cellulose. The utilization of industrial wastes and byproduct streams as fermentation media could improve the cost-competitiveness of BC production. This paper examines the feasibility of using typical wastes generated by industry sectors as sources of nutrients (carbon and nitrogen) for the commercial-scale production of BC. Numerous preliminary findings in the literature data have revealed the potential to yield a high concentration of BC from various industrial wastes. These findings indicated the need to optimize culture conditions, aiming for improved large-scale production of BC from waste streams.

Short Ligand, Cysteine-Modified Warnericin RK Antimicrobial Peptides Favor Highly Sensitive Detection of Legionella pneumophila.

Culture-based methods for the detection of Legionella pneumophila are prohibitively slow and frequently inadequate. The problem has been addressed with biosensing technology that employs a variety of ligands for the specific capture of bacteria. However, the limited success of the application of mammalian antibodies, aptamers, and nucleic acid-based probes for sensitive biosensing has generated growing interest in exploring alternative biosensing architectures, such as those based on antimicrobial peptides (AMP) that are known for their attractive therapeutic applications. We report on the successful employment of cysteine-modified warnericin RK AMP for the operation of a highly sensitive biosensor of L. pneumophila based on digital photocorrosion of GaAs/AlGaAs nanoheterostructures. The replacement of the relatively cumbersome procedure commonly applied for the attachment of antibodies to COOH-terminated mercaptohexadecanoic acid self-assembled monolayers has allowed for a significant reduction in the distance at which bacteria are immobilized above the biosensor surface. An important consequence of this approach is the attractive limit of detection of L. pneumophila estimated at 2 × 102 CFU/mL. The target bacteria were captured four times more efficiently than P. fluorescens, B. subtilis, and E. coli, which is highly promising for environmental monitoring.

Microbial synergistic interactions enhanced power generation in co-culture driven microbial fuel cell.

An understanding of the inter-species relationships, especially their metabolic network in a mixed-culture system, is crucial to design an effective inoculum for enhancing the power generation of wastewater fed microbial fuel cell (MFC). In the present study, the influence of microbial mutualistic interactions on the power generation of palm oil mill effluent fed MFCs has been widely investigated by designing several co-culture and mixed culture inoculums. Among the different inoculum compositions, the highest power density of 14.8 W/m3 was achieved by Pseudomonas aeruginosa and Klebsiella variicola co-culture inoculum due to their synergistic relationships which were inter-linked via fermentation-based metabolites. Besides, the interaction of K. variicola and Bacillus cereus positively influenced the power generation resulting in a maximum power density of 11.8 W/m3 whereas the antagonistic relationship between B. cereus and P. aeruginosa resulted in a lower power generation of 1.9 W/m3. The microbial mutualistic interactions were investigated with polarization, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), as well as by using metabolite and biofilm analysis. It was observed that the synergism between bacteria enhanced power generation through the production of higher electron shuttling mediators and efficient biofilm formation as evidenced by polarization, CV and EIS analysis. In contrast, the antagonistic relationship resulted in production of cell inhibiting metabolites leading to the formation of ineffective biofilm. These findings demonstrate that the synergistic interaction between or within microorganisms is emergent in designing co-culture or mixed-culture inoculum for achieving maximum power generation in MFCs.

Bio-electrochemical power generation in petrochemical wastewater fed microbial fuel cell.

The petrochemical wastewater (PCW) from acrylic acid plants possesses a very high chemical oxygen demand (COD) due to the presence of acrylic acid along with other organic acids. The treatment of PCW by conventional aerobic and anaerobic methods is energy intensive. Therefore, the treatment of PCW with concurrent power generation by employing microbial fuel cell (MFC) could be a potential alternative to solve the energy and environmental issues. This study demonstrates the potentiality of PCW from acrylic acid plant with an initial COD of 45,000 mg L-1 generating maximum power density of 850 mW m-2 at a current density of 1500 mA m-2 using acclimatized anaerobic sludge (AS) as biocatalyst. The predominant microbes present in acclimatized AS were identified using Biolog GEN III analysis, which include the electrogenic genera namely Pseudomonas spp. and Bacillus spp. along with methanogenic archea Methanobacterium spp. The mechanism of electron transfer was elucidated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) which clearly demonstrated the natural metabolite-based electron transfer across the electrode/biofilm/solution interface. The abundance of the electron shuttle metabolites was increased with the microbial growth in the bulk solution as well as in the biofilm leading to a high power generation. The COD removal efficiency and the coulombic efficiency (CE) were found to be 40% and 21%, respectively after 11 days of operation using initial COD of 45,000 mg L-1. The low COD removal efficiency could drastically be increased to 82% when the initial COD of PCW was 5000 mg L-1 generating a power density of 150 mW m-2. The current work proves the feasibility of the MFC for the treatment of acrylic acid plant PCW using acclimatized anaerobic sludge (AS) as a biocatalyst.

Optimization of co-culture inoculated microbial fuel cell performance using response surface methodology.

Microbial fuel cells (MFCs) are considered as promising technology to achieve simultaneous wastewater treatment and electricity generation. However, operational and technological developments are still required to make it as a sustainable technology. In the present study, response surface methodology (RSM) was used to evaluate the effects of substrate concentration, co-culture composition, pH and time on the performance of co-culture (Klebsiella variicola and Pseudomonas aeruginosa) inoculated double chamber MFC. From the statistical analysis, it can be seen that the performance of MFC was not influenced by the interaction between the initial COD and time, pH and time, pH and initial COD, time and initial COD. However, the interaction between the inoculum composition and time, pH and the inoculum composition, initial COD and inoculum composition significantly influenced the performance of MFC. Based on the RSM results, best performance (power density and COD removal efficiency) was obtained when the inoculum composition, initial COD, pH and time were about 1:1, 26.690 mg/L, 7.21 and 15.50 days, respectively. The predictions from the model were in close agreement with the experimental results suggesting that the proposed model could adequately represent the actual relationships between the independent variables generating electricity and the COD removal efficiency.

Microbial lipid extraction from Lipomyces starkeyi using irreversible electroporation.

The aim of the study was to investigate the feasibility of using irreversible electroporation (EP) as a microbial cell disruption technique to extract intracellular lipid within short time and in an eco-friendly manner. An EP circuit was designed and fabricated to obtain 4 kV with frequency of 100 Hz of square waves. The yeast cells of Lipomyces starkeyi (L. starkeyi) were treated by EP for 2-10 min where the distance between electrodes was maintained at 2, 4, and 6 cm. Colony forming units (CFU) were counted to observe the cell viability under the high voltage electric field. The forces of the pulsing electric field caused significant damage to the cell wall of L. starkeyi and the disruption of microbial cells was visualized by field emission scanning electron microscopic (FESEM) image. After breaking the cell wall, lipid was extracted and measured to assess the efficiency of EP over other techniques. The extent of cell inactivation was up to 95% when the electrodes were placed at the distance of 2 cm, which provided high treatment intensity (36.7 kWh m-3 ). At this condition, maximum lipid (63 mg g-1 ) was extracted when the biomass was treated for 10 min. During the comparison, EP could extract 31.88% lipid while the amount was 11.89% for ultrasonic and 16.8% for Fenton's reagent. The results recommend that the EP is a promising technique for lowering the time and solvent usage for lipid extraction from microbial biomass. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:838-845, 2018.

Technical difficulties and solutions of direct transesterification process of microbial oil for biodiesel synthesis.

Microbial oils are considered as alternative to vegetable oils or animal fats as biodiesel feedstock. Microalgae and oleaginous yeast are the main candidates of microbial oil producers' community. However, biodiesel synthesis from these sources is associated with high cost and process complexity. The traditional transesterification method includes several steps such as biomass drying, cell disruption, oil extraction and solvent recovery. Therefore, direct transesterification or in situ transesterification, which combines all the steps in a single reactor, has been suggested to make the process cost effective. Nevertheless, the process is not applicable for large-scale biodiesel production having some difficulties such as high water content of biomass that makes the reaction rate slower and hurdles of cell disruption makes the efficiency of oil extraction lower. Additionally, it requires high heating energy in the solvent extraction and recovery stage. To resolve these difficulties, this review suggests the application of antimicrobial peptides and high electric fields to foster the microbial cell wall disruption.

Determinants of exposure to mass media family planning messages among indigenous people in Bangladesh: a study on the Garo.

This paper evaluates exposure to mass media family planning (FP) messages among the Garo, an indigenous community in Bangladesh. A sample of 223 currently married Garo women were selected purposively from two districts where most of the Garo population live. The analysis demonstrated that television was the most significant form of mass media to disseminate FP messages among the recipients - more so than radio and newspapers. About 80.6% of the respondents had heard of FP messages through television, while for the radio and newspapers the percentages were 55.3% and 22.7% respectively. The contraceptive prevalence rate is much higher (79.5%) in the study area than the national level (55.8%). A linear logistic regression model was employed to identify the confluence of different demographic and socioeconomic characteristics on mass media FP messages. Regarding exposure to FP messages, four independent variables out of six had significant effects on the exposure to FP messages through any one of the types of media, i.e. radio, television and newspapers. These independent variables were age, level of education, occupation and number of children.

Antibacterial activity of Leonurus sibiricus aerial parts.

Different solvent extracts (carbon tetrachloride, chloroform, acetone and methanol) of Leonurus sibiricus were studied for their antibacterial activity. Carbon tetrachloride and chloroform extracts showed a broad spectrum of antibacterial activity.

Analgesic and anti-inflammatory activity of Leonurus sibiricus.

The methanolic extract of Leonurus sibiricus aerial parts injected intraperitoneally at dose of 250 and 500 mg/kg showed a significant analgesic effect in acetic acid-induced writhing in mice. Moreover, when given orally to rats at dose of 200 and 400 mg/kg, it showed a significant anti-inflammatory activity against carrageenin induced rat paw edema in rats.