Corrigendum: Improvement of antioxidant activity and active ingredient of Dendrobium officinale via microbial fermentation.

[This corrects the article DOI: 10.3389/fmicb.2023.1061970.].

Improvement of antioxidant activity and active ingredient of Dendrobium officinale via microbial fermentation.

This study used brewer's yeast to ferment Dendrobium officinale and single-factor and orthogonal experiments were conducted to determine the optimal fermentation conditions. The antioxidant capacity of Dendrobium fermentation solution was also investigated by in vitro experiments, which showed that different concentrations of fermentation solution could effectively enhance the total antioxidant capacity of cells. The fermentation liquid was found to contain seven sugar compounds including glucose, galactose, rhamnose, arabinose, and xylose using gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-quadrupole-time of flight mass spectrometry (HPLC-Q-TOF-MS), with the highest concentrations of glucose and galactose at 194.628 and 103.899 µg/ml, respectively. The external fermentation liquid also contained six flavonoids with apigenin glycosides as the main structure and four phenolic acids including gallic acid, protocatechuic acid, catechol, and sessile pentosidine B.

Effects of novel cellulase (Cel 906) and probiotic yeast fermentation on antioxidant and anti-inflammatory activities of vine tea (Ampelopsis grossedentata).

Vine tea (Ampelopsis grossedentata) is a plant resource with good nutritional and medicinal, and is widely consumed in China. This study aimed to develop a functional vine tea fermentation broth using microbial fermentation and cellulase degradation. First, the most suitable probiotics for vine tea fermentation were screened, and the fermentation conditions were optimized. Then, a new cellulase (Cel 906, MW076177) was added to evaluate the changes in the contents of effective substances and to study its efficacy. The results show that saccharomyces cerevisiae Y-401 was identified as the best strain, the optimal fermentation conditions were a time of 94.60 h, feeding concentration of 115.21 g/L, and temperature of about 34.97°C. The vine tea fermentation broth has a strong inhibitory ability on 2,2'-azinobis3-ethylbenzothiazoline-6-sulfonic acid (ABTS) (99.73%), peroxyl (53.15%), superoxide anion radicals (84.13%), and 1,1-Diphenyl-2-trinitrophenylhydrazine (DPPH) (92.48%). It has a decent inhibitory impact on the cell viability, tyrosinase activity (32.25%), and melanin synthesis (63.52%) of B16-F10 melanoma cells induced by α-MSH. Inflammatory cell recruitment was reduced in a zebrafish inflammation model. Therefore, this vine tea fermented broth has strong antioxidant, anti-melanoma, and anti-inflammatory effects, and has healthcare potential as a probiotic tea.

Expression, Characterization, Fermentation, Immobilization, and Application of a Novel Esterase Est804 From Metagenomic Library in Pesticide Degradation.

Esterase, as a type of powerful catabolic enzyme for the degradation of pyrethroid pesticides (PYRs), appears promising in improving the quality of crops and the environment contaminated by pesticide residues. The purpose of this research is to provide a detailed introduction to the enzymatic properties, optimal production and immobilization conditions, and the degradation ability of Est804 for PYRs. The study on enzymatic properties indicated that Est804 was an alkaline esterase with an optimal pH of 8.0 and a broad optimal temperature in the range of 35-50°C. The optimal activity of free Est804 was calculated to be 112.812 U, and the specific enzyme activity was 48.97 U/mg. The kinetic parameters of Est804 were K m = 0.613 mM, k cat = 12,371 s-1, and V m = 0.095 mM/min. The results of the fermentative optimization demonstrated that the optimal conditions included 1.5% of inoculation amount, 30 mL of liquid volume, 28°C of the fermentation temperature, and 18 h of the fermentation time. The optimal medium consists of 15.87 g of yeast powder, 8.00 g of glycerol, and 9.57 g of tryptone in 1 L of liquid. The optimized enzyme activity was 1.68-fold higher than that before optimization. Immobilized Est804 exhibited the highest activity under the optimum preparation conditions, including 0.35 g of chitosan dosage, 0.4 mL of an enzyme, and 4 h at 40°C for adsorption. The degradation rates of Cypermethrin (CYP), fenpropathrin (FE), and lambda-cyhalothrin (LCT) by Est804 within 30 min were 77.35%, 84.73%, and 74.16%, respectively. The present study indicated that Est804 possesses great potential for the treatment of pesticide residues on crops and environmental remediation, conducive to the development of SGNH family esterase against pyrethroid accumulation.

Causal inference methods for vaccine sieve analysis with effect modification.

The protective effects of vaccines may vary depending on individual characteristics, such as age. Traditionally, such effect modification has been examined with subgroup analyses or inclusion of cross-product terms in regression frameworks. However, in many vaccine settings, effect modification may also depend on the infecting pathogen's characteristics, which are measured postrandomization. Sieve analysis examines whether such effects are present by combining pathogen genetic sequence information with individual-level data and can generate new hypotheses on the pathways whereby vaccines provide protection. In this article, we develop a causal framework for evaluating effect modification in the context of sieve analysis. Our approach can be used to assess the magnitude of sieve effects and, in particular, whether these effects are modified by individual-level characteristics. Our method accounts for difficulties occurring in real-world data analysis, such as competing risks, nonrandomized treatments, and differential dropout. Our approach also integrates modern machine learning techniques. We demonstrate the validity and efficiency of our approach in simulation studies and apply the methodology to a malaria vaccine study.

Correction: The tree balance signature of mass extinction is erased by continued evolution in clades of constrained size with trait-dependent speciation.

[This corrects the article DOI: 10.1371/journal.pone.0179553.].

The tree balance signature of mass extinction is erased by continued evolution in clades of constrained size with trait-dependent speciation.

The kind and duration of phylogenetic topological "signatures" left in the wake of macroevolutionary events remain poorly understood. To this end, we examined a broad range of simulated phylogenies generated using trait-biased, heritable speciation probabilities and mass extinction that could be either random or selective on trait value, but also using background extinction and diversity-dependence to constrain clade sizes. In keeping with prior results, random mass extinction increased imbalance of clades that recovered to pre-extinction size, but was a relatively weak effect. Mass extinction that was selective on trait values tended to produce clades of similar or greater balance compared to random extinction or controls. Allowing evolution to continue past the point of clade-size recovery resulted in erosion and eventual erasure of this signal, with all treatments converging on similar values of imbalance, except for very intense extinction regimes targeted at taxa with high speciation rates. Return to a more balanced state with extended post-extinction evolution was also associated with loss of the previous phylogenetic root in most treatments. These results further demonstrate that while a mass extinction event can produce a recognizable phylogenetic signal, its effects become increasingly obscured the further an evolving clade gets from that event, with any sharp imbalance due to unrelated evolutionary factors.