APPLIED AND ENVIRONMENTAL MICROBIOLOGY
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2022
·Vol. 88
·期 19
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IF 5.005
Shuai Liu,Yuwei Gao,Lin Quan,Mei Yang,Yong-Zhong Wang,Changjun Hou
An increase in exoenzyme production can be enhanced by environmental stresses such as graphene oxide (GO) stress, but the link between the two events is still unclear. In this work, the effect of GO as an environmental stress factor on exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) biosynthesis was investigated in Bacillus subtilis Z2, and a plausible mechanism by which cytosolic Ca2+ regulates lignocellulolytic enzyme production in B. subtilis Z2 subjected to GO stress was proposed. The filter paper-hydrolyzing (FPase [representing total cellulase]), carboxymethylcellulase (CMCase [representing endoglucanase]), and β-glucosidase activities and extracellular protein concentration of the wild-type strain under 10 μg/mL GO stress were 1.37-, 1.64-, 1.24-, and 1.16-fold those of the control (without GO stress), respectively. Correspondingly, the transcription levels of lignocellulolytic enzyme genes, cytosolic Ca2+ level, and biomass concentration of B. subtilis were all increased. With lignocellulolytic enzyme from B. subtilis used to hydrolyze alkali-pretreated rice straw, the released reducing sugar concentration reached 265.53 mg/g, and the removal rates of cellulose, hemicellulose, and lignin were 52.4%, 30.1%, and 7.5%, respectively. Furthermore, transcriptome data revealed that intracellular Ca2+ homeostasis played a key role in regulating the levels of gene transcription related to the synthesis of lignocellulolytic enzymes and exoenzymes. Finally, the use of Ca2+ inhibitors (LaCl3 and EDTA) and deletion of spcF (a calmodulin-like protein gene) further demonstrated that the overexpression of those genes was regulated via calcium signaling in B. subtilis subjected to GO stress.IMPORTANCE To effectively convert lignocellulose into fermentable sugars, high lignocellulolytic enzyme loading is needed. Graphene oxide (GO) has been shown to promote exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) production in some microorganisms; however, the regulatory mechanism of the biosynthesis of lignocellulolytic enzymes under GO stress remains unclear. In this work, the lignocellulolytic enzyme production of B. subtilis under GO stress was investigated, and the potential mechanism by which B. subtilis enhanced lignocellulolytic enzyme production through the calcium signaling pathway under GO stress was proposed. This work revealed the role of calcium signaling in the production of enzymes under external environmental stress and provided a direction to facilitate lignocellulolytic enzyme production by B. subtilis.
研究领域:
微生物学
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分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Bioengineered
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2018
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IF 1.639
Yanshun Kang,Xiaolin Xu,Huiran Pan,Jing Tian,Weihua Tang,Siqi Liu
In this report, the decolorization features of extracellular enzymes and mycelia separately prepared from Aspergillus sp. TS-A CGMCC 12,964 (120 h) were investigated. The fermentation broth of TS-A degraded 98.6% of Mordant Yellow 1 (50 mg/L) at an initial pH 6 within 1 h with over 70% of the dye (50 mg/L) degraded by extracellular enzymes and 18.8% removed by live mycelia. The degradation products of the dye were analyzed by UV-Vis and FTIR spectra. The decolorization rates of extracellular enzymes and mycelia were examined under different contact periods, dye concentrations and pH values. The extracellular enzymes exhibited excellent degradation activity under weak acidic conditions. In addition, biosorption models of mycelia fitted well the Langmuir isotherm model and the pseudo-second-order kinetic equation. Although the decolorization process was achieved through the synergistic effects of mycelia and extracellular enzymes, decolorization was dominated by the biodegradation activity of the extracellular enzymes from TS-A.
研究领域:
环境科学
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微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL BIODETERIORATION & BIODEGRADATION
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2025
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IF 4.1
Nazish Muzaffar,Shujie Zhang,Qian Li,Yuhui Yang,Yanli Xie,Yuan Tian
Aflatoxin B 1 (AFB 1 ) and Zearalenone (ZEN) are highly toxic mycotoxins commonly present in cereal-based foods, making their degradation a crucial research area for ensuring food safety. This study demonstrated that extracellular components mediated the biodegradation of AFB 1 and ZEN from Bacillus amyloliquefaciens HNGD-T8, isolated from fermented tea. The cell-free supernatants achieved 99.57 % and 99.9 % degradation at 80 °C for AFB 1 and ZEN, respectively. Notably, Mn 2+ enhanced the degradation of both mycotoxins. Simultaneous degradation of AFB 1 and ZEN was achieved at 78.02 % and 93.74 %, respectively. Ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) analysis revealed that both mycotoxins were broken down into different metabolites, with AFB 1 converting into (C 17 H 12 O 7 , C 13 H 10 O 4 ) and ZEN transforming into (C 18 H 22 O 7 , C 17 H 24 O 4 ). Degradation of AFB 1 and ZEN led to the disruption of their active sites and the formation of derivative compounds. Subsequent toxicity assessment using zebrafish larvae demonstrated that these degradation products exhibited reduced toxicity. In maize flour, AFB 1 and ZEN degraded 74.20 % and 59.57 %, respectively, while simultaneous degradation achieved 66.23 % and 78.07 %. Given its potent degradation ability, Mn 2+ -enhanced activity, thermostability, and effectiveness in maize flour, these findings underscore the promising potential of HNGD-T8 for mitigating mycotoxin contamination in food matrices and contributing to sustainable food safety solutions.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2021
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IF 10.588
Jingjing Du,Wenrui Qv,Yulong Niu,Mingxiang Qv,Kai Jin,Jinyou Xie,Zehong Li
Many studies have proved the impacts of nanoplastic pollution in freshwaters on aquatic organisms and ecosystems. To explore toxic mechanisms of nanoplastics on stream functioning, we conducted a microcosm experiment to investigate the effects of polystyrene nanoparticles (PS NPs, 1–100 μg L −1 ) on the process of leaf litter decomposition mediated by the microbial community . The chronic exposure to PS NPs at 1 and 100 μg L −1 caused significant decreases in leaf litter decomposition and nutrient (carbon and nitrogen) releases. During the ecological process, some extracellular enzymes (i.e., β-glucosidase, glycine-aminopeptidase, and phenol oxidase) rather than fungal biomass were suppressed. Besides, decreases in the relative abundance of Anguillospora and Setophaeosphaeria weakened their functions in leaf litter decomposition. Thus, the microcosm experiment showed that PS NPs inhibited stream leaf decomposition by modulating the microbial metabolic activity and fungal community structure. Overall, the results of this study provide evidence for the consequences of nanoplastic pollution on freshwater microbial community and stream ecosystem functioning, which is conducive to evaluate the potential risks of nanoplastics in aquatic environments.
研究领域:
环境科学
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微生物学
·
生态学
✓ 已验证
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Yan Liu,Hua Ma,Juan Huang,Zhe Li,Yu Pan,Yiwen Du
The release of carbonaceous nanomaterials (CNMs) into the environment inevitably affects the surrounding microenvironment, biochemical processes of microbes, and even entire ecosystems. However, the knowledge of the impact of CNMs on the environmental microbial activities and further natural organic matter biodegradation is still less known. Here we investigated the impact of three CNMs (single-walled carbon nanotubes , graphene, and oxidized graphene) on extracellular enzymes activities of a fungal strain ( Cladosporium sp.) and lignin biodegradation. All three CNMs increased the activities of three non-specific enzymes (laccase, manganese peroxidase, and lignin peroxidase) to different degrees, among which manganese peroxidase activity increased significantly, with an average promotion of 20% within 18 days. Meanwhile, structural characterization revealed the transformations of CNMs caused by fungal biodegradation. CNMs stimulation fungal enzyme activities further enhanced lignin degradation. Adsorption experiments and electrochemistry analysis demonstrated the mechanism that CNMs acted as adsorbent of extracellular enzymes as well as electron conductors, which enhanced extracellular direct electron transfer between enzymes and lignin and facilitated lignin conversion and degradation. Our results highlight the potential effect of CNMs on the lignin degradation by fungi, and require consideration when evaluating the environmental effects of CNMs on microbial communities or even carbon cycling across whole ecosystems.
研究领域:
环境科学
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微生物学
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生物技术
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生物化学
✓ 已验证
DOI
高影响因子
Food Bioscience
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2024
·
IF 4.8
Dangfeng Wang,Benyou Zhang,Yunting Wang,Likun Ren,Yuqiong Meng,Rui Ma,Shulin Wang,Zhiteng Liu,Yang Jiang,Fangchao Cui,Tingting Li,Jianrong Li
LuxR solos sense exogenous signaling molecules and regulate microbial behaviors, thus facilitating intra- and inter-species communication among bacteria. However, studies on the role of LuxR solos in regulating the spoilage potential of specific spoilage organisms are limited. In this study, we screened a LuxR solo EvgA, derived from Pseudomonas fluorescens PF08. qRT-PCR and molecular docking results indicated that EvgA responds and binds most strongly to exogenous N -3-tetradecanoyl-L-homoserine lactone (C14-HSL) through hydrogen bonds and hydrophobic interactions, with a –CDOCKER ENERGY of 45.87 kcal/mol. Subsequently, the evgA knockout (Δ evgA ) and complementary evgA (Δ evgA -com) mutants of P. fluorescens PF08 were constructed through homologous recombination. Δ evgA mutants displayed diminished eavesdropping to exogenous C14-HSL (by 18.99 ± 2.09%), reduced adhesion ability (by 30.33 ± 0.36%), attenuated biofilm formation (by 15.97 ± 0.14%), and decreased motility (swarming zones by 4.34 ± 0.002 mm and swimming zones by 4.17 ± 0.11 mm). In addition, EvgA deletion reduced spoilage factor production (hydrolysis zone), which included extracellular proteases, lipases, and biogenic amines (by 4.45 ± 0.51 mm, 10.12 ± 0.10 mm, and 14.41 ± 0.57 mm, respectively), thereby diminishing the spoilage of salmon fillets stored at 4 °C. Notably, the addition of exogenous C14-HSL promoted the spoilage ability of all strains. This study emphasizes the important role of LuxR solo EvgA in AHLs-mediated quorum sensing and the spoilage potential of P. fluorescens PF08, which is expected to be a new target for controlling the spoilage of aquatic products.
研究领域:
微生物学
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食品科学
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分子生物学
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生物化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）