Effect of high oxygen pretreatment of whole tuber on anti-browning of fresh-cut potato slices during storage.

The surface browning usually occurs on fresh-cut potato during storage. The effect of short-time high oxygen pretreatment on anti-browning of fresh-cut potato slices was investigated. The whole potato tubers were firstly immersed in the oxygen concentration of 21%, 60% and 80% for 20 min. Then, the potatoes were peeled, cut and stored at 4 °C for 8 days. The results showed that the short-time 80% oxygen pretreatment possessed significantly anti-browning effect by retarding the increase of polyphenol oxidase (PPO) activity and the accumulation of malondialdehyde (MDA) content, maintaining the cell integrity. Meanwhile, the 80% oxygen treatment could increase the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD), and the total phenolic content. Importantly, the 80% oxygen treatment could effectively improve the antioxidant capacity. Overall, all results suggest that the short-time high oxygen pretreatment holds great promise on anti-browning of fresh-cut potato.

Sequencing and Analysis of Chrysanthemum carinatum Schousb and Kalimeris indica. The Complete Chloroplast Genomes Reveal Two Inversions and rbcL as Barcoding of the Vegetable.

Chrysanthemum carinatum Schousb and Kalimeris indica are widely distributed edible vegetables and the sources of the Chinese medicine Asteraceae. The complete chloroplast (cp) genome of Asteraceae usually occurs in the inversions of two regions. Hence, the cp genome sequences and structures of Asteraceae species are crucial for the cp genome genetic diversity and evolutionary studies. Hence, in this paper, we have sequenced and analyzed for the first time the cp genome size of C. carinatum Schousb and K. indica, which are 149,752 bp and 152,885 bp, with a pair of inverted repeats (IRs) (24,523 bp and 25,003) separated by a large single copy (LSC) region (82,290 bp and 84,610) and a small single copy (SSC) region (18,416 bp and 18,269), respectively. In total, 79 protein-coding genes, 30 distinct transfer RNA (tRNA) genes, four distinct rRNA genes and two pseudogenes were found not only in C. carinatum Schousb but also in the K. indica cp genome. Fifty-two (52) and fifty-nine (59) repeats, and seventy (70) and ninety (90) simple sequence repeats (SSRs) were found in the C. carinatum Schousb and K. indica cp genomes, respectively. Codon usage analysis showed that leucine, isoleucine, and serine are the most frequent amino acids and that the UAA stop codon was the significantly favorite stop codon in both cp genomes. The two inversions, the LSC region ranging from trnC-GCA to trnG-UCC and the whole SSC region were found in both of them. The complete cp genome comparison with other Asteraceae species showed that the coding area is more conservative than the non-coding area. The phylogenetic analysis revealed that the rbcL gene is a good barcoding marker for identifying different vegetables. These results give an insight into the identification, the barcoding, and the understanding of the evolutionary model of the Asteraceae cp genome.

Carbon and steel surfaces modified by Leptothrix discophora SP-6: characterization and implications.

Leptothrix discophora SP-6, a type of manganese(Mn)-oxidizing bacteria, has been known to accumulate Mn oxides from the aqueous environment and thus play a key role in microbiologically influenced corrosion by increasing the electrochemical potential of steel and other metals. Similarly, this bacterium was found to modify the surface of glassy carbon in aqueous solution and increase its potential (i.e., ennoblement). In the latter case, biomineralized Mn oxides can be used as cathodic reactants for a new generation of microbial fuel cells featuring a biocathode. In this preliminary study, factors affecting the biofilm formation and biomineralization processes were examined. The inflow of air into the culture medium was found essential to sustain the ennoblement of substrate electrodes. The OCP and FESEM/EDS data indicated that a smoother initial substrate surface generally led to better ennoblement. Polarizing the carbon electrode at +500 mV(SCE) for 15 min was found to facilitate the ennoblement on carbon electrodes, and so did coating it with a poly(L-lysine) layer. Independent of substrate material, initial surface roughness, and pretreatment, there were three parameters in the EIS equivalent circuit that correlated well with the OCP indicating the level of ennoblement by L. discophora SP-6, i.e., electrolyte resistance, double-layer capacitance, and low-frequencies capacitance. These fascinating findings merit further investigation as they may shed light on the fundamental bacteria/substrate interactions and help advance the knowledge base needed forthe engineering applications.