Zheng Ma

Plant pathogenic fungi seriously threaten global crop production, and endophytic fungi are promising reservoirs of bioactive antifungal metabolites. Three undescribed polyester derivatives, talapolyesters I–K (1–3), along with thirteen known compounds including 15G256ω (4), 15G256ι (5), 15G256α (6), talapolyester E (7), 15G256α-1 (8), 15G256α-2 (9), 15G256α-2-me (10), 15G256ν (11), ES-242-3 (12), dongtinganthracene A (13), penicillide (14), 3-methyl-6-hydroxy-8-methoxy-3,4-dihydroisocoumarin (15), and (R)-6-hydroxymellein (16), were isolated from the endophytic fungus Talaromyces striatoconidius WI-F2. Their chemical structures were elucidated comprehensively using NMR and MS spectroscopic analyses, combined with alkaline hydrolysis. Compounds 4–8 exhibited in vitro promising antifungal activity against Fusarium oxysporum f. sp. cubense, with half-maximal inhibitory concentration (IC₅₀) values of 9.72, 21.07, 7.89, 8.91 and 9.65 μg/mL respectively, all markedly lower than that of ketoconazole (46.23 μg/mL). Molecular docking simulations further validated the observed antifungal activity, with binding energies ranging from −9.01 to −12.25 kcal/mol, indicative of stronger binding affinity compared with benzamidine (−6.80 kcal/mol). This study offers new clues for research on antifungal agents.

Gibberella fujikuroi QJGA4-1, a filamentous fungus, is recognized for its production of various gibberellic acids (GAs) secondary metabolites, such as GA₃, GA₄, GA₇, and GA₉. Among these, GA₄₊₇ has attracted considerable interest due to its distinct bioactivity. Its generally low yield level during fermentation presents a challenge for large-scale production. In our investigation, a combination of atmospheric and room temperature plasma (ARTP) mutagenesis and antibiotic stress screening was used to obtain a high-yielding mutant strain. Following a two-step mutagenesis, the GA₄₊₇ production of mutant strain G. fujikuroi M-1 reached 373.12 ± 14.23 mg/L, marking a 14.41% increase compared to the wild-type (WT) strain. The result of scanning electron microscope indicated that the hyphae of G. fujikuroi M-1 were thinner than that of WT strain, suggesting that ARTP mutagenesis affected both cell growth and GA₄₊₇ biosynthesis of G. fujikuroi. In addition, one-factor-at-a-time experiments were carried out to initially assess carbon sources, nitrogen sources, and inorganic salts. This was succeeded by optimizing the fermentation medium by using response surface methodology, resulting in an elevated GA₄₊₇ production of 780.10 ± 30.00 mg/L in G. fujikuroi M-1, which showed an 120.96% increase in production of GA₄₊₇ compared to that produced by G. fujikuroi QJGA4-1 in original culture medium. Combining ARTP mutation with medium optimization is an effective approach for improvement of GA₄₊₇ production.

Ribosome engineering technology typically involves resistance screening of streptomycin and rifampin to introduce point mutations in genes ribosomal protein S12 (rpsL) or RNA polymerase (rpoB), thereby enhancing the synthesis level of secondary metabolites in Streptomyces. Currently, directly introducing copies of genes rpsL and rpoB carrying "beneficial mutations" to construct diploids has become a more rapid and efficient method for obtaining high-yielding Streptomyces strains. We directly introduced these beneficial mutations (rpsL: K88E/P91S; rpoB: S433L/H437Y/R440C) to construct single or combined merodiploids. Introducing rpsL-K88E promoted secondary metabolite biosynthesis in both strains S. coelicolor M145 and S. diastatochromogenes 1628, notably increasing tetramycin A production by 66% in 1628-rpsL-K88E. However, rpsL-P91S yielded no significant positive effects. Regarding rpoB, the M145-rpoB-H437Y strain showed a modest enhancement, with actinorhodin and undecylprodigiosin yields increasing by 20% and 22%. In S. diastatochromogenes 1628, introducing rpoB-H437Y, rpoB-R440C and rpoB-S433L promoted the synthesis of toyocamycin and tetraene macrolides to varying degrees. Constructing a diploid by directly introducing the rpsL and rpoB genes carrying "beneficial mutations" is an effective strategy to enhance the synthesis level of secondary metabolites, whether for the model strain S. coelicolor M145 or the industrial strain S. diastatochromogenes 1628.

We first screened for strong constitutive promoters by analyzing transcriptomics data under various fermentation conditions, focusing on genes with sustained high expression levels. Then, we validated the expression strength of 21 candidate promoters using β-glucuronidase enzymatic activity and qRT-PCR assays and observed that promoter P_30S demonstrated consistently strong expression and efficacy in Streptomyces rimosus M527. The higher expression level and utility of P_30S were further confirmed in three different host strains, including the industrial strain Streptomyces diastatochromogenes 1628. In this strain, overexpression of the toyA gene, a positive regulator, under the control of P_30S significantly increased toyocamycin (TM) production, outperforming permE^* in improving the TM yield. Similarly, in S. rimosus M527, P_30S was superior to permE^* in increasing rimocidin production through the overexpression of the acc_sr gene, which encodes acetyl-CoA carboxylase. Moreover, P_30S successfully activated a cryptic gene cluster responsible for TM biosynthesis in S. rimosus M527 via CRISPR/Cas9-mediated knock-in.

解淀粉芽孢杆菌(Bacillus amyloliquefaciens LX-6)因具有中性蛋白酶

Background: We previously identified a regulator NsdA_sr, which negatively regulated rimocidin biosynthesis in Streptomyces rimosus M527. However, the exact regulatory mechanism of NsdA_sr on rimocidin production remains unknown. Results: In this study, firstly, transcriptomic data demonstrated that the differentially expressed genes resulting from the over-expression of nsdA _sr were primarily associated with several key metabolic pathways, including glycolysis, oxidative phosphorylation, and ribosome-related genes, all of which were downregulated. This directly impacted the concentrations of CoA and NADH, as confirmed by concentration measurement assays. Subsequently, the results of the ChIP-seq experiments revealed that NsdA_sr directly binds to 49 target genes. Notably, these include RS18275 and RS18290 (both involved in fatty acid degradation) as well as rpoB (related to DNA transcription). The validity of the ChIP-seq assay for these three genes was further supported by in vitro electrophoretic mobility shift assays. Regarding RS18275 and RS18290, the results revealed that the binding of NsdA_sr to these elements led to the downregulation of gene expression. This, in turn, resulted in a decrease in the levels of butyryl-CoA and malonyl-CoA, which are known precursors for rimocidin biosynthesis. Consequently, this negatively impacted on the biosynthesis of rimocidin. In the case of rpoB, the results indicated that NsdA_sr binding led to a downregulation of overall protein levels. This was determined by enzymatic activity of report gene GUS and Western blot assay. Consequently, this resulted in a decrease in rimocidin yield. Conclusion: This study reveals NsdA_sr’s dual role in limiting rimocidin production by suppressing metabolic precursors and modulating protein expression. Integrated transcriptomic and ChIP-seq analyses provide critical insights into its regulatory mechanisms.

Electrostatic fields are crucial for achieving the highly efficient filtration of airborne pollutants. However, the dissipation of static charges over time, especially under humid conditions, limits their practical application. In this study, we present a self-charging air filter (SAF) powered by a triboelectric nanogenerator (TENG). This SAF is integrated into a commercial mask, termed SAFM, which can effectively capture and degrade airborne pollutants without requiring an external power source. By leveraging the triboelectric effect during breathing, the TENG within the SAFM continuously replenishes static charges, maintaining the triboelectric field. The system employs a cellulose aerogel/Ti₃C₂T_x composite as the electron donor and an esterified cellulose-based electrospun nanofiber as the electron acceptor. Remarkably, the triboelectric field significantly enhances filtration performance, with the SAF achieving up to 95.7% filtration efficiency for particulate matter as small as 0.3 μm. This work underscores the potential of TENG-powered triboelectric fields in the development of multifunctional, human-machine interactive facemasks.

The rational design, activity prediction, and adaptive application of biological elements (bio-elements) are crucial research fields in synthetic biology. Currently, a major challenge in the field is efficiently designing desired bio-elements and accurately predicting their activity using vast datasets. The advancement of artificial intelligence (AI) technology has enabled machine learning and deep learning algorithms to excel in uncovering patterns in bio-element data and predicting their performance. This review explores the application of AI algorithms in the rational design of bio-elements, activity prediction, and the regulation of transcription-factor-based biosensor response performance using AI-designed elements. We discuss the advantages, adaptability, and biological challenges addressed by the AI algorithms in various applications, highlighting their powerful potential in analyzing biological data. Furthermore, we propose innovative solutions to the challenges faced by AI algorithms in the field and suggest future research directions. By consolidating current research and demonstrating the practical applications and future potential of AI in synthetic biology, this review provides valuable insights for advancing both academic research and practical applications in biotechnology.

The transposon mutagenesis strategy has been employed to generate random insertion mutants and analyze the correlation between genes and secondary metabolites in the genus Streptomyces. In this study, our primary objective was to identify an unknown gene involved in rimocidin biosynthesis and elucidate its role in rimocidin production in Streptomyces rimosus M527. To achieve this, we established a random mutant library of S. rimosus M527 using a Tn5 transposon-mediated random mutagenesis strategy. Among the 137 isolated mutants, M527-G10 and M527-W5 exhibited the most significant variations in antagonistic activity against the plant pathogenic fungus Fusarium oxysporum f. sp. cucumerinum. Specifically, M527-G10 displayed a 72.93% reduction, while M527-W5 showed a 49.8% increase in rimocidin production compared to the wild-type (WT) strain S. rimosus M527. Subsequently, we employed a plasmid rescue strategy to identify the insertion loci of the transposon in the genomes of mutants M527-G10 and M527-W5, revealing a response regulator transcription factor (rrt) and a hypothetical protein (hyp), respectively. The roles of rrt and hyp in rimocidin biosynthesis were determined through gene deletion, overexpression in the WT strain, and complemented expression in the transposon mutants. Notably, the gene-deletion mutants M527-ΔRRT and M527-ΔHYP exhibited similar behavior in rimocidin production compared to the corresponding transposon mutants M527-G10 and M527-W5, suggesting that transposon insertions in genes rrt and hyp led to alterations in rimocidin production. Furthermore, both gene deletion and overexpression of rrt and hyp had no discernible effects on cell growth. These results reveal that genes rrt and hyp have positive and negative impacts on rimocidin production in S. rimosus M527, respectively.