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The model predictive torque control (MPTC) schemes of three-level neutral point clamped (3L-NPC) inverters have multiobjective cost functions, including three weighting factors (WFs). With the lack of theoretical approaches that make rapid the WFs online-tuning, the paper proposes a predictive flux control strategy with weighting factor free cost function (WFFPFC) for 3L-NPC inverter fed induction motor (IM) drives. It consists in discarding the following: 1) the flux WF through a generation of the reference stator flux vector; 2) the NP voltage WF by introducing a comparative condition of the dc-bus capacitors voltages at the beginning of each sector; and 3) the switching number WF by selecting a group of seven voltage vectors per sector that enables the clamping of the stator phase voltages at low or high level of the dc-bus voltage. The proposed approach is then applied to a case study, considering a comparison among the performance of the proposed WFF-PFC, the model predictive flux control (MPFC), and the MPTC strategies, considering both steady-state and transient behaviors of the 3L-NPC inverter-fed IM drive. It is found that the elimination of the WFs leads to an improvement of drive features except a slight increase of the NP voltage. Simulation results are validated by experiments.

Marine vascular plants such as Posidonia oceanicaform symbiotic associations with microbiota to enhance nutrient acquisition, supporting plant growth and fitness. The beneficial symbiotic bacteria can theoretically persist in Posidonia oceanicaleaves and balls deposed on sandy beaches as marine cellulosic wastes, opening up new opportunities for their valorization in biotechnological processes. The objective of this work was to characterize the bacterial communities associated with P. oceanicawaste (POW) samples collected from four sandy beaches in northeastern Tunisia. Analysis of metataxonomic datasets showed high bacterial diversity and richness in POW samples with a prevalence of bacteria belonging to the phyla proteobacteria, firmicutes, and actinobacteria. Analysis of alpha and beta diversity metrics also indicated that POW samples show distinct bacterial profiles and abundances at taxa levels from species to phylum. Combined metataxonomic and chemical data revealed that low bacterial diversity correlated with low contents of cellulose and hemicellulose in POW samples, maybe indicating stressed microbial communities. Both culture-dependent and culture-independent techniques showed that POW harbored halophilic bacteria with tremendous potential for carbohydrate-active enzymes (CAZymes) production (cellulases, xylanases, laccases, peroxidases, etc.) and plant growth-promoting activities such as enhancement of nutrients supply/availability and resistance to salt stress by accumulating osmolytes. The selected enzyme-producing halotolerant PGPB, Nocardiopsis synnemataformansPT2, and Halobacillus trueperiPHm3 have been successfully applied in the bioconversion of POW into bioethanol. A maximum bioethanol yield of 41.17% (equal to 10.45 g ethanol/100 g of POW) was recorded at 30 °C and 37 °C for 72 h of fermentation. These results indicated that POW maybe considered as a source of enzyme-producing–plant growth-promoting bacteria with potential applications in sustainable agriculture and bioenergetics.

The present study examines the use of waste cooking oil (WCO) as a substrate for medium-chain-length polyhydroxyalkanoates (mcl-PHA) production by Pseudomonas rhizophilaS211. The genome analysis revealed that the S211 strain has a mcl-PHA cluster (phaC1ZC2DFI) encoding two class II PHA synthases (PhaC1 and PhaC2) separated by a PHA depolymerase (PhaZ), a transcriptional activator (PhaD) and two phasin-like proteins (PhaFI). Genomic annotation also identified a gene encoding family I.3 lipase that was able to hydrolyze plant oils and generate fatty acids as favorable carbon sources for cell growth and PHA synthesis via β-oxidation pathway. Using a three-variable Doehlert experimental design, the optimum conditions for mcl-PHA accumulation were achieved in 10% of WCO-based medium with an inoculum size of 10% and an incubation period of 48 h at 30 °C. The experimental yield of PHA from WCO was 1.8 g/L close to the predicted yield of 1.68 ± 0.14 g/L. Moreover, 1H nuclear magnetic resonance spectroscopy analysis confirmed the extracted mcl-PHA. Overall, this study describes P. rhizophilaas a cell factory for biosynthesis of biodegradable plastics and proposes green and efficient approach to cooking oil waste management by decreasing the cost of mcl-PHA production, which can help reduce the dependence on petroleum-based plastics.

Considering the current growing interest in new and improved enzymes for use in a variety of applications, the present study aimed to characterize a novel detergent-stable serine alkaline protease from the extremophilic actinobacterium Microbacterium metalliduransTL13 (MmSP) using a combined in silico and experimental approach. The MmSP showed a close phylogenetic relationship with high molecular weight S8 peptidases of Microbacteriumspecies. Moreover, its physical and chemical parameters computed using Expasy’s ProtParam tool revealed that MmSP is hydrophilic, halophilic and thermo-alkali stable. 3D structure modelling and functional prediction of TL13 serine protease resulted in the detection of five characteristic domains: [catalytic subtilase domain, fibronectin (Fn) type-III domain, peptidase inhibitor I9, protease-associated (PA) domain and bacterial Ig-like domain (group 3)], as well as the three amino acid residues [aspartate (D182), histidine (H272) and serine (S604)] in the catalytic subtilase domain. The extremophilic strain TL13 was tested for protease production using agricultural wastes/by-products as carbon substrates. Maximum enzyme activity (390 U/gds) was obtained at 8th day fermentation on potato peel medium. Extracellular extract was concentrated and partially purified using ammonium sulfate precipitation methodology (1.58 folds purification fold). The optimal pH, temperature and salinity of MmSP were 9, 60 °C and 1 M NaCl, respectively. The MmSP protease showed broad pH stability, thermal stability, salt tolerance and detergent compatibility. In order to achieve the maximum stain removal efficacy by the TL 13 serine protease, the operation conditions were optimized using a Box–Behnken Design (BBD) with four variables, namely, time (15–75 min), temperature (30–60 °C), MmSP enzyme concentration (5–10 U/mL) and pH (7–11). The maximum stain removal yield (95 ± 4%) obtained under the optimal enzymatic operation conditions (treatment with 7.5 U/mL of MmSP during 30 min at 32 °C and pH9) was in good agreement with the value predicted by the regression model (98 ± %), which prove the validity of the fitted model. In conclusion, MmSP appears to be a good candidate for industrial applications, particularly in laundry detergent formulations, due to its high hydrophilicity, alkali-halo-stability, detergent compatibility and stain removal efficiency.