Moutai is a world-famous traditional Chinese liquor with complex taste and aroma, which are considered to be strongly influenced by the quality of fermentation starters (Daqu). However, the role of microbial communities in the starters has not been fully understood. In this study, we revealed the microbial composition of 185 Moutai starter samples, covering three different types of starters across immature and mature phases, and functional gene composition of mature starter microbiome. Our results showed that microbial composition patterns of immature starters varied, but they eventually were similar and steady when they became mature starters, after half-year storage and subsequent mixing. To help identify two types of immature starters, we selected seven operational taxonomic unit (OTU) markers by leave-one-out cross validation (LOOCV) and an OTU classified as Saccharopolyspora was the most decisive one. For mature starters, we identified a total of 16 core OTUs, one of which annotated as Bacillus was found positively associated with saccharifying power. We also identified the functional gene and microbial composition in starch and cellulose hydrolysis pathways. Microbes with higher abundances of alpha-glucosidase, alpha-amylase, and glucoamylase probably contributed to high saccharifying power. Overall, this study reveals the features of Moutai starter microbial communities in different phases and improves understanding of the relationships between microbiota and functional properties of the starters.

Mangroves, as important and special ecosystems, create unique ecological environments for examining the microbial gene capacity and potential for producing bioactive compounds. However, little is known about the biogeochemical implications of microbiomes in mangrove ecosystems, especially the variations between pristine and anthropogenic mangroves. To elucidate this, we investigated the microbial taxonomic and functional shifts of the mangrove microbiomes and their potential for bioactive compounds in two different coastal mangrove ecosystems in southern China. A gene catalogue, including 87 million unique genes, was constructed, based on deep shotgun metagenomic sequencing. Differentially enriched bacterial and archaeal taxa between pristine mangroves (Guangxi) and anthropogenic mangroves (Shenzhen) were found. The Nitrospira and ammonia-oxidizing archaea, specifically, were more abundant in Shenzhen mangroves, while sulfate-reducing bacteria and methanogens were more abundant in Guangxi mangroves. The results of functional analysis were consistent with the taxonomic results, indicating that the Shenzhen mangrove microbiome has a higher abundance of genes involved in nitrogen metabolism while the Guangxi mangrove microbiome has a higher capacity for sulfur metabolism and methanogenesis. Biosynthetic gene clusters were identified in the metagenome data and in hundreds of de novo reconstructed nonredundant microbial genomes, respectively. Notably, we found different biosynthetic potential in different taxa, and we identified three high quality and novel Acidobacteria genomes with a large number of BGCs. In total, 67,278 unique genes were annotated with antibiotic resistance, indicating the prevalence and persistence in multidrug-resistant genes in the mangrove microbiome. IMPORTANCE This study comprehensively described the taxonomy and functionality of mangrove microbiomes, including their capacity for secondary metabolite biosynthesis and their ability to resist antibiotics. The microbial taxonomic and functional characteristics differed between geographical locations, corresponding to the environmental condition of two diverse mangrove regions. A large number of microbial biosynthetic gene clusters encoding novel bioactivities were found, and this can serve as a valuable resource to guide novel bioactive compound discovery for potential clinical uses.

A Gram-staining-positive, motile and short-rod-shaped actinobacterium designated 9W16Y-2^T was isolated from surface-sterilized leaves of reed (Phragmites australis) collected from Taklamakan Desert in Xinjiang Uygur Autonomous Region, China. Colonies were pale greenish yellow, circular, smooth, and convex. The 16S rRNA gene sequence of strain 9W16Y-2^T exhibited highest sequence similarities with Aeromicrobium camelliae CGMCC 1.12942^T (99.0%) and Aeromicrobium erythreum NRRL B-3381^T (97.2%). Phylogenetic analyses based on 16S rRNA gene sequences and single-copy phylogenetic marker genes (pMGs) showed that strain 9W16Y-2^T belonged to the genus Aeromicrobium and formed a monophyletic clade with Aeromicrobium camelliae CGMCC 1.12942^T. Furthermore, average nucleotide identity (ANI) and DNA-DNA hybridization (DDH) clearly separated strain 9W16Y-2^T from the other species of the genus Aeromicrobium with values below the thresholds for species delineation. The G+C content of the genomic DNA is 68.9 mol%. The diagnostic diamino acid of the cell-wall peptidoglycan was ll-diaminopimelic acid. The predominant menaquinone was MK-9(H₄). The major fatty acids (> 10% of the total fatty acids) were C_18:0 10-methyl (TBSA) (28.2%), C_16:0 (21.0%), C_16:0 2-OH (20.8%) and C_18:1ω9c (12.8%). The polar lipid profile comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, an unidentified aminophospholipid and an unidentified lipid. Based on the phylogenic, phenotypic and chemotaxonomic features, strain 9W16Y-2^T represents a novel species of the genus Aeromicrobium, for which the name Aeromicrobium endophyticum sp. nov. is proposed. The type strain is 9W16Y-2^T (= CGMCC 1.13876^T = JCM 33141^T).

A Gram-negative, aerobic, motile and short-rod-shaped bacterium, designated strain 5T4P-12-1T, was isolated from a piece of surface-sterilized bark of Aegiceras corniculatum collected from Cotai Ecological Zones in Macao, China and tested by a polyphasic approach to clarify its taxonomic position. Strain 5T4P-12-1T grew optimally with 0–1 % (w/v) NaCl at 30 °C and at pH 7.0–8.0. The 16S rRNA gene sequence of strain 5T4P-12-1T had the highest similarity (96.7 %) to Aureimonas altamirensis DSM 21988T. Phylogenic analysis based on 16S rRNA gene sequences and coding sequences of 98 protein clusters showed that the strain represented a novel genus of the family Aurantimonadaceae . The predominant quinone system of strain 5T4P-12-1T was ubiquinone 10. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylmethylethanolamine, an unidentified aminophospholipid, three unidentified aminolipids, three unidentified phospholipids and three unidentified lipids. The major fatty acids (>10 % of total fatty acids) were C18 : 1ω7c (55.4 %) and C18 : 1 2-OH (15.6 %). The DNA G+C content of strain 5T4P-12-1T was 66.5 mol%. Based on the phylogenic, phenotypic and chemotaxonomic features, strain 5T4P-12-1T is considered to represent a novel species of a new genus in the family Aurantimonadaceae , for which the name Mangrovicella endophytica gen. nov., sp. nov. is proposed. The type strain is 5T4P-12-1T (=KCTC 62053T=CGMCC 1.16279 T).

A Gram-stain-positive, aerobic, non-motile, non-spore-forming and short-rod-shaped actinobacterium, designated strain 1T4Z-3T, was isolated from a piece of surface-sterilized branch of Aegiceras corniculatum collected from the Cotai Ecological Zones in Macao, China. Comparative 16S rRNA gene sequence analysis showed that strain 1T4Z-3T was clearly affiliated to the genus Amnibacterium and exhibited 97.9 % gene sequence similarity to Amnibacterium kyonggiense JCM 16463T, 97.3 % gene sequence similarity to Amnibacterium soli JCM 19015T and less than 96.4 % gene sequence similarities to other genera of the family Microbacteriaceae. Strain 1T4Z-3T had L-2,4-diaminobutyric acid as the diagnostic cell-wall diamino acid. The major fatty acids (>10 % of total fatty acids) were iso-C16 : 0 (46.6 %) and anteiso-C15 : 0 (27.3 %). The predominant menaquinones of strain 1T4Z-3T were MK-11 (81.4 %) and MK-12 (14.1 %). The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, six unidentified glycolipids, four unidentified phospholipids and two unidentified lipids. The DNA G+C content of strain 1T4Z-3T was 71.4 mol%. Based on the phylogenetic, phenotypic and chemotaxonomic features, strain 1T4Z-3T is considered to represent a novel species of the genus Amnibacterium , for which the name Amnibacterium endophyticum sp. nov. is proposed. The type strain of Amnibacterium endophyticum is 1T4Z-3T (=KCTC 39983T=CGMCC 1.16066T).