Inhibitory Effect of Non-Saccharomyces Starmerella bacillaris CC-PT4 Isolated from Grape on MRSA Growth and Biofilm.

Methicillin-resistant Staphylococcus aureus (MRSA) is a notorious pathogen with biofilm-forming and drug-resistant properties that make it difficult to eradicate. In this study, the inhibition of MRSA (ATCC 43300) by Starmerella bacillaris CC-PT4 (CGMCC No. 23573) was evaluated. The results showed that the inhibition of MRSA growth and biofilm was caused by S. bacillaris CC-PT4 cell-free supernatant (CFS). The CFS of S. bacillaris CC PT4 at different times can effectively inhibit the formation of MRSA biofilm, remove the preformed biofilm, and down-regulate the related genes that promote the formation of biofilm. Afterwards, untargeted metabolomics was performed to analyze the CFS of S. bacillaris CC-PT4. Several molecules with antibacterial and inhibitory biofilm effects from the CFS were found, one of which, 2-amino-1-phenylethanol (APE), has not been reported to have antiMRSA ability before. In this study, molecular docking analysis and in vitro experiments were used to verify the function of APE to inhibit MRSA. These results indicate that S. bacillaris CC-PT4 CFS can effectively inhibit MRSA which has potential application value in controlling MRSA.

Whole-Genome Analysis of Starmerella bacillaris CC-PT4 against MRSA, a Non-Saccharomyces Yeast Isolated from Grape.

Starmerella bacillaris is often isolated from environments associated with grape and winemaking. S. bacillaris has many beneficial properties, including the ability to improve the flavor of wine, the production of beneficial metabolites, and the ability to biocontrol. S. bacillaris CC-PT4 (CGMCC No. 23573) was isolated from grape and can inhibit methicillin-resistant Staphylococcus aureus and adaptability to harsh environments. In this paper, the whole genome of S. bacillaris CC-PT4 was sequenced and bioinformatics analyses were performed. The S. bacillaris CC-PT4 genome was finally assembled into five scaffolds with a genome size of 9.45 Mb and a GC content of 39.5%. It was predicted that the strain contained 4150 protein-coding genes, of which two genes encoded killer toxin and one gene encoded lysostaphin. It also contains genes encoding F1F0-ATPases, Na(+)/H(+) antiporter, cation/H(+) antiporter, ATP-dependent bile acid permease, major facilitator superfamily (MFS) antiporters, and stress response protein, which help S. bacillaris CC-PT4 adapt to bile, acid, and other stressful environments. Proteins related to flocculation and adhesion have also been identified in the S. bacillaris CC-PT4 genome. Predicted by antiSMASH, two secondary metabolite biosynthesis gene clusters were found, and the synthesized metabolites may have antimicrobial effects. Furthermore, S. bacillaris CC-PT4 carried genes associated with pathogenicity and drug resistance. Overall, the whole genome sequencing and analysis of S. bacillaris CC-PT4 in this study provide valuable information for understanding the biological characteristics and further development of this strain.

Full inhibition of Whangkeumbae pear polyphenol oxidase enzymatic browning reaction by l-cysteine.

The enzymatic browning reaction caused by polyphenol oxidase (PPO) has a negative effect on the processing of fruits and vegetables. However, some chemical inhibitors have been used to prevent enzymatic browning reaction, although they may be toxic and potentially hazardous to use in food. In this study, PPO was isolated and purified from the Whangkeumbae pear, and four food grade inhibitors were used to prevent the enzymatic browning reaction. The results showed that the PPO activity increased by 32.93-fold; its yield was 0.2 U/100 U, and the specific activity was 519,895.73 U/mg protein. The molecular weight of the PPO was approximately 44 kDa. The most potent inhibitor was l-cysteine, which fully inhibited the PPO activity at a concentration of 0.8 mg/mL. The type of inhibition of l-cysteine was noncompetitive. It suggests that l-cysteine can be utilized to prevent enzymatic browning reaction during the processing of pear juice.

Thin cloud removal from single satellite images.

A novel method for removing thin clouds from single satellite image is presented based on a cloud physical model. Given the unevenness of clouds, the cloud background is first estimated in the frequency domain and an adjustment function is used to suppress the areas with greater gray values and enhance the dark objects. An image, mainly influenced by transmission, is obtained by subtracting the cloud background from the original cloudy image. The final image with proper color and contrast is obtained by decreasing the effect of transmission using the proposed max-min radiation correction approach and an adaptive brightness factor. The results indicate that the proposed method can more effectively remove thin clouds, improve contrast, restore color information, and retain detailed information compared with the commonly used image enhancement and haze removal methods.