Nanofiber applications in microbial fuel cells for enhanced energy generation: a mini review

Microbial fuel cells (MFCs) represent simple devices that harness the metabolic activities of microorganisms to produce electrical energy from diverse sources such as organic waste and sustainable biomass. Because of their unique advantage to generate sustainable energy, through the employment of biodegradable and repurposed waste materials, the development of MFCs has garnered considerable interest. Critical elements are typically the electrodes and separator. This mini-review article presents a critical assessment of nanofiber technology used as electrodes and separators in MFCs to enhance energy generation. In particular, the review highlights the application of nanofiber webs in each part of MFCs including anodes, cathodes, and membranes and their influence on energy generation. The role of nanofiber technology in this regard is then analysed in detail, focusing on improved electron transfer rate, enhanced biofilm formation, and enhanced durability and stability. In addition, the challenges and opportunities associated with integrating nanofibers into MFCs are discussed, along with suggestions for future research in this field. Significant developments in MFCs over the past decade have led to a several-fold increase in achievable power density, yet further improvements in performance and the exploration of cost-effective materials remain promising areas for further advancement. This review demonstrates the great promise of nanofiber-based electrodes and separators in future applications of MFCs.

The influence of growth conditions on strain differentiation within the Lactobacillus acidophilus group using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry profiling

RATIONALE

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling of bacteria is often used to distinguish isolates beyond the species level, even to the level of individual strains. However, the influence of bacterial growth conditions on the discriminatory power of the method to the strain level has not yet been properly evaluated.

METHODS

For the purpose of this study, we used an extraction protocol recommended for clinical laboratories for MALDI-TOF MS profiling of bacteria. Seventeen closely related strains of the Lactobacillus acidophilus group were cultivated under various growth conditions (growth medium, time, and temperature) and analyzed.

RESULTS

Out of a total of 327 samples, 80 % were correctly assigned to the species level and 13 % only to the genus level. When using data obtained from strains cultured for lengthy periods (7 days), the identification success rate was reduced due to poor signal quality, whereas with shorter cultivation times there was no influence of growth conditions on the assignment of particular strains to their corresponding species. However, variations in certain cultivation parameters were found to influence identification and differentiation of most of the examined strains. Strain discrimination was frequently found to be dependent on the selection of culture conditions. MALDI-TOF MS data treatment (strain-specific peak detection, BioTyper scoring, subtyping, or cluster analysis) also contributed to the discriminatory power of the method.

CONCLUSIONS

When MALDI-TOF MS profiling of bacteria is used for strain discrimination, the cultivation conditions should be properly optimized and controlled as they significantly contribute to the discriminatory power of the method.