Milk kefir fermentation has been used in households for generations. Consumption of milk kefir has been associated with various health benefits, presumably from the probiotics of yeast and bacteria that make up the kefir grains. In addition, many of the microbes are known to produce novel antimicrobial compounds that can be used for other applications. The microbes living inside kefir grains differ significantly depending on geographical location and production methods. In this study, we aimed to use metagenomic analysis of fermented milk by using three different kefir grains (kefir 1, kefir 2, and kefir 3) from different US sources. We analyzed the microbial compositions of the three milk fermentation samples. This study revealed that each sample contains unique and distinct groups of microbes, kefir 1 showed the least diversity, and kefir 3 showed the highest diversity. Kefir 3 is rich in Proteobacteria while kefir 2 is dominated by the Firmicutes. Using bacterial indicator growth analyses carried out by continuous readings from microplate-based bioreactor assays suggested that kefir 2 fermentation filtrate has higher antibacterial property. We have screened 30 purified cultures of kefir 2 sample and isolated two lactic acid bacteria strains with higher antibacterial activities; the two strains were identified as Leuconostoc mesenteroides 28-1 and Lentilactobacillus kefiri 25-2 by 16S genomic PCR with confirmed antibacterial activities of fermentation filtrate after growing under both aerobic and anaerobic conditions.
A superfast, room-temperature, one-step carrier-solvent-assisted interfacial reaction process was developed to prepare Ag/AgFeO2 composite nanocrystals (NCs) of less than 10 nm in size within a 1 min reaction time. These composite NCs were with a direct energy band gap of 2.0 eV and were paramagnetic, making them suitable for optical activation and magnetic manipulation. These composite NCs, applied as a photocatalyst for the treatment of HeLa cells, achieved a significant reduction of 74% in cell viability within 30 min. These Ag/AgFeO2 composite NCs proved to be a promising magnetically guidable photocatalyst for cancer cell treatment.
Bivalves have high diversity, widely distributed in various aquatic environments, including saltwater, brackish water and freshwater. Bivalves are known to rich in polysaccharides and have wide applications in functional foods, pharmaceuticals, and industrial research. Despite many relevant reports are available, the information is poorly organized. Therefore, in this study, we conducted a comprehensive scientific review on the potential bioactivity of polysaccharides derived from bivalves. In general, the polysaccharides derived from bivalves possess various bioactive properties, including anticancer, antioxidant, anticoagulant and immunomodulatory activities. The bioactivity of these biomolecules highly depends on the bivalve species, extraction methods, purification methods, dosages, etc. The information in this study can provide an overview of the bioactivities of bivalve polysaccharides. This is very useful to be used as a guide for identifying the health benefits of polysaccharides derived from different bivalve species.
Syngas, consisting of equimolar CO and H2, is an important feedstock for large-scale production of a wide range of commodity chemicals including aldehyde, methanol, ammonia, and other oxygenated chemicals. Dry reforming of methane (DRM), proceeding by reacting greenhouse gases, CO2 and CH4, at high temperatures in the presence of a metal catalyst, is considered one of the most environmentally friendly routes for syngas production. Nevertheless, nonprecious metal-based catalysts, which can operate at relatively low temperatures for high product yields and selectivities, are required to drive the DRM process for industrial applications effectively. Here, we developed NiCo@C nanocomposites from a corresponding NiCo-based bimetallic metal-organic framework (MOF) to serve as high-performance catalysts for the DRM process, achieving high turnover frequencies (TOF) at low temperatures (>5.7 s-1 at 600 °C) and high product selectivities (H2/CO = 0.9 at 700 °C). The incorporation of Co in Ni catalysts improves the operation stability and light-off stability. The present development for MOF-derived nanocomposites opens a new horizon for design of DRM catalysts.