Anode modification with carbon nanomaterials is an important strategy for the improvement of microbial fuel cell (MFC) performance. The presence of nitrogen in the carbon network, introduced as active nitrogen functional groups, is considered beneficial for anode modification. In this aim, nitrogen-containing carbon nanostructures (NCNs) with different morphologies were obtained via carbonization of polyaniline and were further investigated as anode modifiers in MFCs. The present study investigates the influence of NCN morphology on the changes in the anodic microbial community and MFC performance. Results show that the nanofibrillar morphology of NCNs is beneficial for the improvement of MFC performance, with a maximum power density of 40.4 mW/m², 1.25 times higher than the anode modified with carbonized polyaniline with granular morphology and 2.15 times higher than MFC using the carbon cloth-anode. The nanofibrillar morphology, due to the well-defined individual nanofibers separated by microgaps and micropores and a better organization of the carbon network, leads to a larger specific surface area and higher conductivity, which can allow more efficient substrate transport and better bacterial colonization with greater relative abundances of Geobacter and Thermoanaerobacter, justifying the improvement of MFC performance.

Polyhydroxyalkanoates (PHAs) are biodegradable bioplastics that can be manufactured sustainably and represent a promising green alternative to petrochemical‐based plastics. Here, we describe the complete genome of a new marine PHA‐producing bacterium—Photobacterium ganghwense (strain C2.2), which we have isolated from the Black Sea seashore. This new isolate is psychrotolerant and accumulates PHA when glycerol is provided as the main carbon source. Transmission electron microscopy, specific staining with Nile Red visualized via epifluorescence microscopy and gas chromatography analysis confirmed the accumulation of PHA. This is the only PHA‐producing Photobacterium for which we now have a complete genome sequence, allowing us to investigate the pathways for PHA production and other secondary metabolite synthesis pathways. The de novo assembly genome, obtained using open‐source tools, comprises two chromosomes (3.5, 2 Mbp) and a megaplasmid (202 kbp). We identify the entire PHA synthesis gene cluster that encodes a class I PHA synthase, a phasin, a 3‐ketothiolase, and an acetoacetyl‐CoA reductase. No conventional PHA depolymerase was identified in strain C2.2, but a putative lipase with extracellular amorphous PHA depolymerase activity was annotated, suggesting that C2.2 is unable to degrade intracellular PHA. A complete pathway for the conversion of glycerol to acetyl‐CoA was annotated, in accordance with its ability to convert glycerol to PHA. Several secondary metabolite biosynthetic gene clusters and a low number of genes involved in antibiotic resistance and virulence were also identified, indicating the strain's suitability for biotechnological applications.

Bacterial contamination during fuel storage can lead to fuel biodegradation (biodeterioration) or infrastructure problems (i.e., microbiologically influenced corrosion (MIC), biofouling, etc.). Jet A-1 storage tank samples were screened, and 23 morphologically distinct bacterial strains were isolated. 6 isolates revealed biofilm initiation capacity. For 12 isolates the alkane monooxygenase gene (alkB) was successfully detected. The 12 alkB-possessing isolates were 16S rDNA sequences identified as belonging to Bradyrhizobium, Sphingomonas, Bacillus, Pseudomonas, Methylobacterium and Lelliottia genera. In addition to possessing enzymatic equipment (AlkB) required for alkane oxidation, 10 out of 12 isolates were able to use Jet A-1 and n-tetradecane as their sole carbon source and energy. Biofilm initiation capacity and the ability to grow on different hydrocarbons highlights once again that fuel bacterial contamination can lead to serious fuel and storage system alterations. In contrast, their adaptation to high concentrations of hydrocarbons highlights the potential use of our isolates for bioremediation processes.