ABSTRACT
Synergistic microbial co-culture has been an efficient and energy-saving strategy to produce lignin-degrading enzymes (LDEs), including laccase, manganese peroxidase, and versatile peroxidase. However, the regulatory mechanism of microbial co-culture is still unclear. Herein, the extracellular LDE activities of four white-rot fungi were significantly increased by 88-544% over monoculture levels when co-cultured with Rhodotorula mucilaginosa. Ptf6 was demonstrated from the 9 million Y1H clone library to be a shared GATA transcription factor in the four fungi, and could directly bind to the laccase gene promoter. Ptf6 exists in two alternatively spliced isoforms under monoculture, namely Ptf6-α (1078 amino acids) containing Cys2/Cys2-type zinc finger and Ptf6-ß (963 amino acids) lacking the complete domain. Ptf6 responded to co-culture by up-regulation of both its own transcripts and the proportion of Ptf6-α. Ptf6-α positively activated the production of most LDE isoenzymes and bound to four GATA motifs on the LDEs' promoter with different affinities. Moreover, Ptf6-regulation mechanism can be applicable to a variety of microbial co-culture systems. This study lays a theoretical foundation for further improving LDEs production and providing an efficient way to enhance the effects of biological and enzymatic pretreatment for lignocellulosic biomass conversion.
Subject(s)
Laccase , Lignin , Lignin/metabolism , Laccase/genetics , Transcription Factors/genetics , Coculture Techniques , Amino AcidsABSTRACT
Fucoidans, sulfated polysaccharides in brown algae, were depolymerized though high-pressure hydrolysis, and their antibacterial activity, structural properties, and antibacterial mechanisms were investigated in this work. The fucoidans from Laminaria japonica show no antibacterial activity before depolymerization; however, their depolymerized products can effectively (p<0.05) inhibit the proliferation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The structure-activity study demonstrated that lower molecular weight and stronger polyanionic property can promote the antibacterial activity. And the depolymerized fucoidans exhibited better antibacterial activity against E. coli than against S. aureus. The results also indicated that the bactericidal pathway of depolymerized fucoidans should be through destruction of the cytomembranes and the target molecules are the membrane proteins, which can result in changed membrane fluidity and/or activated autophagocytosis. Therefore, the depolymerized fucoidans possess potential appliance values in partly or totally replacing antibiotics in our daily life.
Subject(s)
Anti-Bacterial Agents/pharmacology , Laminaria/chemistry , Polysaccharides/pharmacology , Anti-Bacterial Agents/isolation & purification , Escherichia coli/drug effects , Polysaccharides/isolation & purification , Staphylococcus aureus/drug effects , Structure-Activity RelationshipABSTRACT
With increasingly serious eye exposure to light stresses, such as light-emitting diodes, computers, and widescreen mobile phones, efficient natural compounds for preventing visible light-induced retinal damages are becoming compelling needs in the modern society. Fucoxanthin, as the main light absorption system in marine algae, may possess an outstanding bioactivity in vision protection because of its filtration of blue light and excellent antioxidative activity. In this work, both in vitro and in vivo simulated visible light-induced retinal damage models were employed. The in vitro results revealed that fucoxanthin exhibited better bioactivities than lutein, zeaxanthin, and blueberry anthocyanins in inhibiting overexpression of vascular endothelial growth factor, resisting senescence, improving phagocytic function, and clearing intracellular reactive oxygen species in retinal pigment epithelium cells. The in vivo experiment also confirmed the superiority of fucoxanthin than lutein in protecting retina against photoinduced damage. This excellent bioactivity may be attributed to its unique structural features, including allenic, epoxide, and acetyl groups. Fucoxanthin is expected to be an important ocular nutrient in the future.
Subject(s)
Laminaria/chemistry , Light/adverse effects , Plant Extracts/administration & dosage , Protective Agents/administration & dosage , Retina/radiation effects , Retinal Diseases/drug therapy , Vegetables/chemistry , Xanthophylls/administration & dosage , Animals , Cell Line , Humans , Oxidative Stress/drug effects , Oxidative Stress/radiation effects , Rabbits , Reactive Oxygen Species/metabolism , Retina/drug effects , Retina/injuries , Retina/metabolism , Retinal Diseases/metabolism , Vascular Endothelial Growth Factor A/metabolismABSTRACT
A spectral liquid signature analyzer system including a miniature fiber-optic spectrometer is described in this paper. Through the combination of the spectral method and liquid signature analysis technology, the analytical function of the liquid signature analyzer will be improved obviously. With this spectral liquid signature analyzer system, the physical, chemical, and mechanical characteristics of the tested sample can be obtained at the same time. In detail, that is the light intensity signal, the equivalent drop volume signal, and the spectroscopic data from the miniature spectrometer. And after merging the information data, the three-dimensional fingerprint that is unique to the liquid sample is attainable. This three-dimensional fingerprint includes the full information we gain from the experiment, and it provides visualized differences in various samples. The application of spectral analysis makes it possible for further research into the chemical compositions of liquid samples and supplies discrimination evidence to different liquids. Therefore, the liquid signature analyzer can be used in more fields related to liquid.
