Extracellular Enzyme Activities and Carbon/Nitrogen Utilization in Mycorrhizal Fungi Isolated From Epiphytic and Terrestrial Orchids

Reshaped local microbiology metabolism by raw tea according to pile fermentation in the dark tea

INTRODUCTION

Traditionally, the mechanism of dark tea quality formation has centered on microorganisms, with quality regulated by manipulating microorganisms and their fermentation environment. Nevertheless, raw teas, the natural selective medium of microbial community, was completely ignored in the formation of dark tea unique flavors.

OBJECTIVES

This study aims to uncover the previously unappreciated interactions between raw tea and microorganisms, demonstrating the significant role of raw tea in the formation of dark tea quality.

METHODS

Sun-dried raw tea (SDT), baked raw tea (BT), and pan-fried raw tea (PFT) were pile fermented. Chemical profiles, microbial communities, and sensory qualities were assessed by metabolomics, high-throughput sequencing, and sensory evaluation, with correlation and multiple factor analyses used to explore their relationships.

RESULTS

Compared to PFT and BT, SDT had 18 % lower flavonoid content and 26 % lower catechin content, which favored dominant Agathobacter and Wickerhamomyces. Wickerhamomyces contributed to flower aroma by producing alcohols, esters and terpenes, while Agathobacter amplified acid production. The distinctive dominant bacterium Acidovorax in BT was positively correlated with alcohols and hydrocarbons, with Pearson's r > 0.6, resulting in a 47 % increase in volatile alcohol level, enhancing the fresh and refreshing attributes. A 70-80 % increase in iron concentration in PFT compared to SDT and BT resulted in the predominance of Geobacter, which exhibited a negative correlation with aldehydes. The presence of distinctive bacteria, Streptococcus and Ligilactobacillus, in PFT led to a significant rise in volatile acid content, increasing from 5 % to 25 %.

CONCLUSION

The chemical profiles of raw tea could reshape local microbiota, which then drives unique qualities of dark tea. This indicates dark tea quality is not passively shaped by the environmental microorganisms, but actively screened by raw tea chemistry. This study paves the way for targeted manipulation of raw tea chemical profiles to achieve desired dark tea flavor characteristics.

Limnobacter olei sp. nov., a Novel Diesel-Degrading Bacterium Isolated from Oil-Contaminated Soil

A bacterial strain P1T, capable of degrading diesel and converting thiosulfate to sulfate was isolated from an oil-contaminated soil sample. The cells were Gram-stain-negative, slightly curved rods and motile with a single polar flagellum. Growth of the strain was observed at 4-45 °C (optimum at 28 °C), at pH 4.0-12.0 (optimum at pH 10.0) and with 0-15.0% (w/v) NaCl (optimum at 2.0%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain P1T was closely related to the members of the genus Limnobacter, with the highest sequence similarity to Limnobacter thiooxidans DSM 13612 T (99.8%), followed by Limnobacter alexandrii LZ-4 T (99.4%), Limnobacter parvus YS8-69 T (98.8%), Limnobacter litoralis KP1-19 T (97.6%), and Limnobacter humi UCM-39 T (97.5%). The draft genome sequence of strain P1T was 3.40 Mb long, with a DNA G + C content of 52.4%. The average nucleotide identity and digital DNA-DNA hybridization values between strain P1T and the closely related type strains were in the range of 71.8-85.1% and 18.1-28.7%, respectively. The predominant cellular fatty acids of strain P1T included C16: 0, summed feature 3 (C16: 1 ɷ7c and/or C16: 1 ɷ6c), summed feature 8 (C18: 1 ɷ7c and/or C18: 1 ɷ6c), and summed feature 7 (C19: 1 ɷ6c and/or C19: 1 ɷ7c and/or C19: 1 cyclo). In addition, the main polar lipid was composed of diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. Q-8 was the sole respiratory quinone. Based on the polyphasic characterization, strain P1T (= KCTC 72814 T = CCTCC AB 2019403 T) represents a novel species of the genus Limnobacter, for which the name Limnobacter olei sp. nov. is proposed.

Effect of Solid-State Fermentation of Hericium erinaceus on the Structure and Physicochemical Properties of Soluble Dietary Fiber from Corn Husk

Corn husk, a by-product of corn starch production and processing, contains high-quality dietary fiber (DF). Our study compares and analyzes the impact of Hericium erinaceus solid-state fermentation (SSF) on the structure and physicochemical characteristics of soluble dietary fiber (SDF) of corn husks. The study also investigates the kinetics of SSF of H. erinaceus in this process. The scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) results revealed significant structural changes in corn husk SDF before and after fermentation, with a significant elevation in the functional group numbers. The data indicate that the fermented corn husk SDF's water-holding, swelling, and oil-holding capacities increased to 1.57, 1.95, and 1.80 times those of the pre-fermentation SDF, respectively. Additionally, the results suggest that changes in extracellular enzyme activity and nutrient composition during SSF of H. erinaceus are closely associated with the mycelium growth stage, with a mutual promotion or inhibition relationship between the two. Our study offers a foundation for corn husk SDF fermentation and is relevant to the bioconversion of maize processing by-products.

Analysis of Faecal Microbiota and Small ncRNAs in Autism: Detection of miRNAs and piRNAs with Possible Implications in Host-Gut Microbiota Cross-Talk

Intestinal microorganisms impact health by maintaining gut homeostasis and shaping the host immunity, while gut dysbiosis associates with many conditions, including autism, a complex neurodevelopmental disorder with multifactorial aetiology. In autism, gut dysbiosis correlates with symptom severity and is characterised by a reduced bacterial variability and a diminished beneficial commensal relationship. Microbiota can influence the expression of host microRNAs that, in turn, regulate the growth of intestinal bacteria by means of bidirectional host-gut microbiota cross-talk. We investigated possible interactions among intestinal microbes and between them and host transcriptional modulators in autism. To this purpose, we analysed, by "omics" technologies, faecal microbiome, mycobiome, and small non-coding-RNAs (particularly miRNAs and piRNAs) of children with autism and neurotypical development. Patients displayed gut dysbiosis related to a reduction of healthy gut micro- and mycobiota as well as up-regulated transcriptional modulators. The targets of dysregulated non-coding-RNAs are involved in intestinal permeability, inflammation, and autism. Furthermore, microbial families, underrepresented in patients, participate in the production of human essential metabolites negatively influencing the health condition. Here, we propose a novel approach to analyse faeces as a whole, and for the first time, we detected miRNAs and piRNAs in faecal samples of patients with autism.