A unique microbiome that metabolizes lactate rather than ethanol for n-caproate production was obtained from a fermentation pit used for the production of Chinese strong-flavour liquor (CSFL). The microbiome was able to produce n-caproate at concentrations as high as 23.41 g/L at a maximum rate of 2.97 g/L/d in batch trials without in-line extraction. Compared with previous work using ethanol as the electron donor, the n-caproate concentration increased by 82.89%. High-throughput sequencing analysis showed that the microbiome was dominated by a Clostridium cluster IV, which accounted for 79.07% of total reads. A new process for n-caproate production was proposed, lactate oxidation coupled to chain elongation, which revealed new insight into the well-studied lactate conversion and carbon chain elongation. In addition, these findings indicated a new synthesis mechanism of n-caproate in CSFL. We believe that this efficient process will provide a promising opportunity for the innovation of waste recovery as well as for n-caproate biosynthesis.

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ε-Poly-L-lysine (ε-PL), a naturally occurring amino acid homopolymer, has been widely used as a food preservative. However, its antimicrobial mechanism has not been fully understood. This study investigated the antimicrobial mode of action of ε-PL on a yeast, Saccharomyces cerevisiae. When treated with ε-PL at the concentration of 500 μg/mL, cell mortality was close to 100% and the phospholipid bilayer curvature, pores, and micelles on the surface of S. cerevisiae were clearly observed by scanning electron microscopy (SEM). At the level of 200 μg/mL, ε-PL significantly inhibited the cell growth of S. cerevisiae. When treated with 50 μg/mL ε-PL, the yeast cell was able to grow but the cell cycle was prolonged. A significant increase in cell membrane permeability was induced by ε-PL at higher concentrations. Metabolomics analysis revealed that the ε-PL stress led to the inhibition of primary metabolic pathways through the suppression of the tricarboxylic acid cycle and glycolysis. It is therefore proposed that the microbiostatic effect of ε-PL at lower levels on S. cerevisiae is achieved by inducing intracellular metabolic imbalance via disruption of cell membrane functions. Moreover, the results suggested that the antimicrobial mechanism of ε-PL on S. cerevisiae can in fact change from microbiostatic to microbicidal when the concentration of ε-PL increased, and the mechanisms of these two modes of action were completely different.

Metal-organic frameworks (MOFs) possess excellent strengths, such as high porosity, large specific surface area, and adjustable structure, showing good potential for applications in gas adsorption and separation, catalysis, conductivity, sensing,...

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The ability to detect multidimensional forces is highly desired for electronic skin (E-skin) sensors. Here, based on single-electrode-mode triboelectric nanogenerators (S-TENGs), fully elastic E-skin that can simultaneously sense normal pressure and shear force has been proposed. With the hemispherical curve-structure design and further structural optimization, the pressure sensor exhibits a high linearity and sensitivity of 144.8 mV/kPa in the low-pressure region. By partitioning the lower tribolayer into two symmetric parts, a multidimensional force sensor has been fabricated in which the output voltage sum and ratio of the two S-TENGs can be used for normal pressure and shear force sensing, respectively. When the multidimensional force sensors are mounted at a two-fingered robotic manipulator, the change of the grabbing state can be recognized, indicating that the sensor may have great application potential in tactile sensing for robotic manipulation, human–robot interactions, environmental awareness, and object recognition.

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