Zhiwei Su

Myxobacteria are fascinating and important prokaryotes with remarkable multicellular behaviors, which make them a model system for studying prokaryotic development and cooperation. Although there have been sporadic discoveries of myxobacterial species unable to fruit, it is unclear whether the non-fruiting characteristic is due to taxon-specific genetic deficiency or suboptimal cultivation conditions. Aggregicoccus is a non-fruiting myxobacterial genus typified by a single validly published species, Ag. edonensis . In this study, we report five novel Aggregicoccus strains, which are classified into three novel type species , Ag. lacus , Ag. agri , and Ag. guangxiensis , based on polyphasic taxonomic analysis. All the Aggregicoccus strains are unable to produce fruiting bodies, but can still sporulate. We compared the genome differences between Aggregicoccus and Myxococcus ; both genera belong to the Myxococcaceae family, and all the genomes are of similar sizes. The results showed that the Aggregicoccus strains are inherently deficient in the fruiting body-associated genomic information (FAGI). We propose an assessment of FAGI for the classification of non-fruiting myxobacterial species. IMPORTANCE: Fruiting body formation is traditionally regarded as a defining trait of myxobacteria. Here, we report that Aggregicoccus spp., including six strains of four species, can sporulate but are deficient in the fruiting body-associated genomic information (FAGI). This demonstrates that the non-fruiting characteristic in Aggregicoccus stems from inherent genetic deficiencies rather than suboptimal cultivation. Our findings highlight the need to assess FAGI presence in classifying non-fruiting lineages, innovate the isolation method, and refine our understanding of the diversity and evolution of the myxobacteria.

The thiazole compounds cystothiazole A (7) and melithiazol F (9) potently inhibited Fusarium sacchari by suppressing its growth and spore germination and disrupting cell membrane integrity.

From the ethanol extract of Brucea javanica seeds, an undescribed C ₁₉ ‐type quassinoid, javanicolide I ( 1 ) and its epimer, javanicolide J ( 2 ), a new indole alkaloid, bruceolline O ( 3 ), a new‐to‐nature 1 H ‐Indole‐3‐butanoic acid, α ‐methyl‐ γ ‐oxobutanoic acid ( 4 ), together with 13 known compounds ( 5 – 17 ) were isolated and structurally characterized by spectroscopic analysis. All compounds were evaluated for antifouling activity against Balanus amphitrite cyprid larval settlement. Aglycone of yadanzioside D ( 6 ) not only exhibits potent anti‐settlement activity but also demonstrates low toxicity, with an EC ₅₀ of 1.06 µg/mL and an LC ₅₀ /EC ₅₀ ratio of 20.68 (>15, indicating low toxicity), outperforming the positive control SeaNine 211. Further resuscitation and zebrafish embryo assays also confirmed its low toxicity, highlighting its potential as a promising antifouling candidate.

Background: The search for environmentally friendly antifouling agents has led to an increased focus on marine natural products. Methods: This study investigated the antifouling potential of lipid fractions extracted from ten marine fungal strains isolated from the Beibu Gulf, China. The lipids were evaluated through a multi-level bioassay approach, including the inhibition of microfouling (against four fouling bacteria: Marinobacterium jannaschii, Vibrio pelagius, Vibrio rotiferianus, and Alteromonas macleodii), the prevention of macrofouling (inhibition of barnacle Amphibalanus reticulatus cyprid settlement), and long-term (90-day) marine field trials. Results: Eight lipid fractions demonstrated inhibitory effects against at least one bacterial strain. Five lipids significantly inhibited barnacle cyprid settlement, with half-maximal effective concentration (EC₅₀) values ranging from 0.21 to 1.81 µg/mL and exhibited low toxicity (half-maximal lethal concentration (LC₅₀) > 50 µg/mL). Notably, four lipid fractions maintained potent antifouling efficacy (>70% inhibition) throughout the 90-day field exposure. Chemical characterization via gas chromatography–mass spectrometry (GC–MS) revealed that the bioactive fractions were predominantly composed of fatty acids and their derivatives. Major identified compounds included palmitic acid, methyl palmitate, linoleic acid, dodecyl-9-ynyl chloroacetate, cis-13-octadecenoic acid, oleic acid, methyl 11,14-octadecadienoate, and (E)-9-octadecenoic acid methyl ester. Conclusions: This work represents the first comprehensive investigation of marine fungal lipids from the Beibu Gulf with multi-target antifouling properties, providing a theoretical foundation and practical candidate compounds for developing eco-friendly antifouling coatings.

Callicarpa nudiflora is one of high medicinal and economic value plants in China, which was recorded in Chinese pharmacopoeia (2020 edition) and widely used to treat tropical bacterial infections, acute infectious hepatitis, and internal and external bleeding. In this study, we assembled the C. nudiflora genome with a size of approximately 597.82 Mb and a contig N50 length of 34.14 Mb. A total of 98.61% of the assembled sequences were anchored to 17 pseudo-chromosomes by using PacBio long reads and Hi-C sequencing data. We totally predicted 31,266 protein-coding genes, of which 92.45% could be annotated in databases such as NR, GO, KOG, and KEGG. In addition, we identified 2,303 rRNAs, 884 MicroRNAs and 531 tRNAs from the genome. The chromosome-scale genome represents a crucial resource for investigating the molecular mechanisms underlying the biosynthesis of medicinal components and facilitates the exploration and conservation of C. nudiflora.

The increasing challenge of marine biofouling, mainly due to barnacle settlement, necessitates the development of effective antifoulants with minimal environmental toxicity. In this study, fifteen derivatives of brusatol were synthesized and characterized using ¹³C-NMR, ¹H-NMR, and mass spectrometry. All the semi-synthesized compounds obtained using the Multi-Target-Directed Ligand (MTDL) strategy, when evaluated as anti-settlement agents against barnacles, showed promising activity. Compound 3 exhibited the highest anti-settlement capacity, with an EC₅₀ value of 0.1475 μg/mL, an LC₅₀/EC₅₀ ratio of 42.2922 (>15 indicating low toxicity), and a resuscitation rate of 71.11%, while it showed no significant phenotypic differences in the zebrafish embryos after treatment for 48 h. The toxicity screening of zebrafish also demonstrated the low ecotoxicity of the selected compounds. Furthermore, homology modeling of the HSP90 structure was performed based on related protein sequences in barnacles. Subsequently, molecular docking studies were conducted on HSP90 using these newly synthesized derivatives. Molecular docking analyses showed that most activated derivatives displayed low binding energies with HSP90, aligning well with the biological results. They were found to interact with key residues in the binding site, specifically ARG243, TYR101, and LEU73. These computational findings are anticipated to aid in predicting the enzyme targets of the tested inhibitors and their potential interactions, thus facilitating the design of novel antifoulants in future research endeavors.

This study investigated the diversity of cultivable marine myxobacteria from Weizhou Island in the Beibu Gulf of Guangxi, with a particular focus on strains exhibiting potential antibacterial activity and associated enzyme production. The Escherichia coli entrapment method and filter paper methods were employed for separation, followed by purification using sequential conversion techniques. Myxobacteria were identified through morphology characterization and 16S rRNA gene sequence analyses. The antibacterial activity against porcine pathogens was assessed using the plate confrontation method, and enzyme activity was evaluated through the plate assay method. From 13 island samples, 28 myxobacteria cultures were isolated, representing 13 species across 8 genera, predominantly Myxococcus. The antibacterial test showed remarkable activity in 9 myxobacteria strains. Cystobacter fuscus (GXIMD 01665c) and Myxococcus virescens (GXIMD 01661b) produced inhibition zones of 54.4?0.18 mm and 57.33?0.09 mm against E. coli L2 and E. coli 10, respectively. The enzyme activity experiment revealed that all 9 strains of myxobacteria could produce protease and cellulase, with 7 strains specifically producing chitinase, 6 strains producing amylase, and 4 producing lipase. These findings highlight the diverse antibacterial properties and enzymatic potential of myxobacteria from Weizhou Island. Strains GXIMD 01665c and GXIMD 01661b emerged as valuable microbial resources, holding great promise for further research and development.

The phylogenetic studies of the tribe Alsineae (Caryophyllaceae) have revealed a clearer boundary between the genus Stellaria and related genera, primarily relying on the morphological characteristics of style 3, stamens 10 and petals deeply bifid. However, the newly-published species in China, which have 5 styles or ten or more lobes per petal, challenge this boundary and necessitate further studies. In this paper, we reviewed six newly-published Chinese species of Stellaria, utilising both molecular phylogenetic evidence from nuclear ribosomal internal transcribed spacer (ITS) and four plastid regions (trnL-F, matK, rbcL, rps16) and morphological evidence. Our results demonstrated that the five new species (Stellaria abaensis, S. multipartita, S. pentastyla, S. procumbens and S. zhuxiensis) were nested within the genus Stellaria, but Stellaria motuoensis was sister to the genus Schizotechium. Herein, we accepted four new Stellaria species and proposed a new combination in Schizotechium and a new synonym in Stellaria. Additionally, we described a new species Stellaria longipedicellata from Sichuan Province, China, which was distinguished from the closely-related species Stellaria decumbens by its glabrous body, linear-lanceolate leaves, long pedicellate flowers, prostrate growth habit and flowers nearly equal to or slightly shorter than sepals. Both molecular and morphological evidence support the treatment of S. longipedicellata as a new species of the genus Stellaria.