INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
·
2022
·
IF 5.911
Zhiling Tang,Haiming Chen,Weijun Chen,Qiuping Zhong,Ming Zhang,Wenxue Chen,Yong-Huan Yun
Pseudomonas fragi is primarily responsible for the spoilage of various foods, especially meat. The aim of this study was to investigate the antibacterial mechanism of 3-carene against P. fragi . 3-Carene treatment decreased the phospholipid content and the fluidity of the cell membrane, induced reactive oxygen species (ROS) generation and affected respiratory chain dehydrogenase, oxoglutarate dehydrogenase and citrate synthase in P. fragi . Metabolomics and proteomics analyses further showed that in the presence of 3-carene, 519 proteins, 136 metabolites in positive ion mode and 100 metabolites in negative ion mode were differentially expressed. These proteins and metabolites were primarily involved in amino acid metabolism, fatty acid degradation, the tricarboxylic acid cycle (TCA cycle) and other processes. Consequently, the stimulation of 3-carene altered cell membrane properties, disturbed important amino acid and energy metabolism, and even caused oxidative stress. Additionally, the results of total viable counts and the total volatile base nitrogen indicated that 3-carene could significantly improve the preservation of refrigerated pork. This study suggested that 3-carene has promising potential to be developed as a food preservative.
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Reaction Chemistry & Engineering
·
2020
·Vol. 5
·期 8
·1397-1404
·
IF 3.441
Xin Pan,Sihua Wu,Deshan Yao,Lian Liu,Lina Zhang,Zixuan Yao,Yan Pan,Siyuan Chang,Bingfeng Li
5-Hydroxymethyl-2-furancarboxylic acid (HMFCA) is a significant added-value intermediate derivatized from the bio-based platform chemical 5-hydroxymethylfurfuraldehyde (HMF). In the HMFCA biosynthesis process, the catalytic performance of the biocatalyst always decreases due to the presence of HMF toxicity, which is not conducive to achieving high product accumulation. Herein, we successfully obtained a new whole-cell biocatalyst from Pseudomonas aeruginosa PC-1, which was first reported to produce HMFCA from HMF. After optimization, 90.1% yield of HMFCA was attained within 6 h using a 100 mM substrate. Importantly, a much lower cell dosage was needed in the process. In order to achieve higher HMFCA accumulation, a fed-batch strategy was developed by using the growing cells from P. aeruginosa PC-1. Consequently, a total concentration of 721 mM HMFCA was obtained from 800 mM HMF within 58 h after 8 cycles of fed-batch, which is the highest concentration to date. The efficient HMFCA production made P. aeruginosa PC-1 a promising whole-cell biocatalyst for selective, large scale biotransformation of HMF.
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Frontiers in Microbiology
·
2021
·
IF 5.64
Zhao Shuxue,Chen Xi,Sun Qianshu,Wang Fei,Hu Chunhui,Guo Lizhong,Bai Jie,Yu Hao
Indole-3-acetic acid (IAA), known as a common plant hormone, is one of the most distributed indole derivatives in the environment, but the degradation mechanism and cellular response network to IAA degradation are still not very clear. The objective of this study was to elucidate the molecular mechanisms of IAA degradation at the protein level by a newly isolated strain Pseudomonas sp. LY1. Label-free quantitative proteomic analysis of strain LY1 cultivated with IAA or citrate/NH4Cl was applied. A total of 2,604 proteins were identified, and 227 proteins have differential abundances in the presence of IAA, including 97 highly abundant proteins and 130 less abundant proteins. Based on the proteomic analysis an IAA degrading (iad) gene cluster in strain LY1 containing IAA transformation genes (organized as iadHABICDEFG), genes of the β-ketoadipate pathway for catechol and protocatechuate degradation (catBCA and pcaABCDEF) were identified. The iadA, iadB, and iadE-disrupted mutants lost the ability to grow on IAA, which confirmed the role of the iad cluster in IAA degradation. Degradation intermediates were analyzed by HPLC, LC-MS, and GC-MS analysis. Proteomic analysis and identified products suggested that multiple degradation pathways existed in strain LY1. IAA was initially transformed to dioxindole-3-acetic acid, which was further transformed to isatin. Isatin was then transformed to isatinic acid or catechol. An in-depth data analysis suggested oxidative stress in strain LY1 during IAA degradation, and the abundance of a series of proteins was upregulated to respond to the stress, including reaction oxygen species (ROS) scavenging, protein repair, fatty acid synthesis, RNA protection, signal transduction, chemotaxis, and several membrane transporters. The findings firstly explained the adaptation mechanism of bacteria to IAA degradation.
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BIOPROCESS AND BIOSYSTEMS ENGINEERING
·
2014
·Vol. 37
·期 11
·2353-2359
·
IF 1.823
Ganasen Ponnarasy,Khan Maksudur Rahman,Kalam M. Abul,Mahmud Mohd Sabri
This paper demonstrates Pseudomonas cepacia lipase catalyzed hydrolysis of p -nitrophenyl palmitate under irradiation of light with wavelengths of 250–750 nm. The reaction follows Michaelis–Menten Kinetics and the light irradiation increases the overall rate of hydrolysis. Using Lineweaver–Burk plot K
M and V
max values for the reaction in presence of light are found to be 39.07 and 66.67 mM/min/g, respectively; while for the same reaction under dark condition, the values are 7.08 and 10.21 mM/min/g. The linear form of enzyme dependent rate of reaction confirms that no mass-transfer limitations are present and the reaction is a kinetically controlled enzymatic reaction.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2016
·Vol. 181
·期 3
·972-985
·
IF 1.606
Wu Hua-Lei,Zhang Jian-Dong,Zhang Chao-Feng,Fan Xiao-Jun,Chang Hong-Hong,Wei Wen-Long
Four uncharacterized ω-transaminases (ωTAs) from Pseudomonas putida NBRC 14164 have been identified and cloned from the pool of fully sequenced genomes. The genes were functionally expressed in Escherichia coli BL21, and the enzymes were purified and characterized. Four TAs showed highly ( S )-selective ωTA activity and converted ( S )-α-methylbenzylamine and pyruvate to acetophenone and l -Ala. The maximum activity of cloned enzymes was in the pH range of 8.0– 8.5 (Pp36420), 8.5 –9. 5 (Pp21050), 9 .0– 9.5 (PpspuC), and 9.5 –1 0 . 5 (PpbauA), and the optimal temperatures were at 35 °C (Pp36420, Pp21050, and PpspuC) and 50 °C (PpbauA), respectively, with K
M of 161.3 mM (Pp21050), 136.7 mM (PpbauA), 398.5 mM (Pp36420), and 130.9 mM (PpspuC) and yielding a catalytic efficiency k
cat / K
M of 0.015, 0.003, 0.012, and 0.023 mM −1 s −1 . Several racemic amines and amino alcohols were resolved by the cloned ωTAs; perfect conversions (48–50 %) were obtained by at least one enzyme, and the residual substrates were left with 97–99 % ee. Kinetic resolution of racemic phenylglycinol was done with PpspuC in a 100-mL scale. Enaniomeric excess of ( S )-phenylglycinol reached 99 % with 45 % isolated yield. The high enantioselectivity and large substrate spectra of the cloned PpTAs showed an attractive potency for biotechnology application in production of chiral amines and amino alcohols.
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BIORESOURCE TECHNOLOGY
·
2025
·
IF 9
Yong Yang,Guangming Zhang,Jie Pan,Zhen Zhang,Ning Mao,Shiwei Wang,Yanmei Sun
Enhanced microbial remediation represents a promising technique for the removal of polycyclic aromatic hydrocarbons (PAHs). However, high-efficiency remediation agents remain limited, including microbial resources and remediation materials. In this study, a novel strain of Pseudomonas xizangensis S4 was isolated from plateau lake sediment, exhibiting a fluoranthene degradation rate of 41.90 % at 50 ppm within 7 d. The key degradation genes identified through genomic and transcriptomic analyses included ndmC , dmpK , dmpB , and dmpH . The metabolites detected via GC–MS analysis were biphenyls, parabens, and phthalate esters. Based on the above results, the degradation mechanisms of fluoranthene were deduced. Furthermore, an efficient remediation agent was developed, utilizing potassium humate-modified biochar to immobilize bacterial cells. The developed remediation agent enhanced the removal efficiency by 16.71 % compared to the single strain. Thus, the application of potassium humate-modified biochar for the immobilization of P. xizangensis S4 represents a promising method for the remediation of PAH-contaminated soil.
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FOOD CONTROL
·
2020
·
IF 4.258
Zhirong Wang,Tao Zhong,Kewei Chen,Muying Du,Guangjing Chen,Xuhui Chen,Kaituo Wang,Zsolt Zalán,Krisztina Takács,Jianquan Kan
In this research, postharvest citrus fruits with blue mold caused by Penicillium italicum were treated with volatile organic compounds (VOCs) produced by Pseudomonas fluorescens ZX incubated on NA and in NB. Treatments with pure individual components of the VOCs were also conducted. The VOCs from P. fluorescens ZX inhibited mycelial growth and conidial germination of P. italicum by 42.14% and 77.86%, respectively. In vivo experiments revealed that blue mold disease incidence and lesion size upon fruits were significantly suppresed by VOCs from P. fluorescens ZX incubated on NA, in NB and on healthy fruits. In addition, the VOCs produced by bacterial fluid provided higher biocontrol efficacy than did that from NA plates. The exposure to VOCs from bacterial fluid of P. fluorescens ZX resulted in morphological abnormalities of the conidia and hyphae of P. italicum . In vitro testing of the individual pure compounds comprising the VOCs suggested that organic acids and sulfur compounds are the active components of VOCs, with dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) exhibiting the highest antifungal activity: concentrations of only 100 and 10 μL/L, respectively, afforded complete inhibition of blue mold on citrus fruits in vivo. Organic acids showed promise for controlling blue mold, but only in sufficiently low concentrations so as not to promote physiological disease or damage in the fruits.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Ying Huang,Lang Bai,Yutong Yang,Zhanhai Yin,Baolin Guo
Burn wounds are susceptible to bacterial infections and are usually accompanied by a large amount of exudate, making the treatment of burn wounds a challenge in the clinic. Here, we developed a biodegradable cryogel with high water absorption and good antibacterial and antibiofilm activity based on gelatin (GT) and silver nanoparticles (Ag NPs) to promote burn wound healing. The porous GT/Ag cryogel had a swelling ratio of up to 4000%, effectively absorbing wound exudate and allowing for gas exchange. Moreover, the GT/Ag cryogel had an excellent killing effect on methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA), which burn wounds are susceptible to, and can effectively remove mature biofilms . In the rat liver defect noncompressible hemorrhage model, GT/Ag cryogels with shape memory performance showed better hemostatic ability than commercial gelatin sponges. Most importantly, the GT/Ag cryogel was more effective than the Tegaderm TM dressing and GT cryogel in promoting wound contraction, collagen deposition, and angiogenesis and reducing inflammation in a PA-infected burn wound model. In addition, GT/Ag cryogels degraded in the body within 4 weeks, which alleviated the pain of peeling the dressing from the wound. Therefore, GT/Ag cryogels with outstanding antibacterial properties and effective absorption of wound exudates are excellent candidates for wound dressings to promote burn wound repair.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2021
·
IF 5.279
Zhirong Wang,Tao Zhong,Xuhui Chen,Bing Yang,Muying Du,Kaituo Wang,Zsolt Zalán,Jianquan Kan
In this study, volatile organic compounds (VOCs) were generated by Pseudomonas fluorescens ZX with incubation in nutrient broth (NB), on NA (NB with agar), and on healthy orange fruits, and pure individual components of VOCs were used to manage citrus green mold infected by Penicillium digitatum. At a concentration of 1 × 1010 cfu/mL, the VOCs from antagonist-containing NA plates inhibited P. digitatum conidial germination and mycelial growth by about 60%, while the VOCs from bacterial fluid exhibited approximately 75% inhibitory effect. Biofumigation by VOCs significantly reduced the disease index, with a higher biocontrol efficacy by VOCs from bacterial fluid (about 51%) than from antagonist-containing NA plates (around 40%) or from antagonist-infested fruit (approximately 24%). Exposure to VOCs led to morphological abnormalities of P. digitatum conidia and hyphae. However, VOCs exhibited poor preventative and curative action against P. digitatum. The storage test showed that biofumigation had no negative effects on fruit quality. Antifungal assays suggested that dimethyl disulfide and dimethyl trisulfide exhibited the highest inhibitory effects, which afforded complete inhibition at the lowest concentrations. In addition, organic acids were also promising in controlling green mold, but only at suitable low concentrations to avoid eliciting fruit’s physiological diseases.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2019
·
IF 2.931
Zitao Zhong,Ran Gao,Qingmei Chen,Li Jia
To ensure the food security and protect public health, development of rapid and reliable approaches to detecting foodborne pathogens is of great significance. In this study, polydopamine-polyethyleneimine (PDA-PEI) copolymer dots are prepared via the self-polymerization of dopamine and cross-linking with branched PEI at room temperature . The PDA-PEI copolymer dots are very stable against photobleaching, extreme pH, as well as high ionic strength . They are used as a fluorescent probe to fabricate a biosensor for rapid and sensitive detection and quantification of Pseudomonas aeruginosa ( P. aeruginosa ). In the biosensor, dual-aptamers of P. aeruginosa are used to label PDA-PEI copolymer dots. Compared to single aptamer labeled PDA-PEI dots, the dual-aptamers labeled PDA-PEI dots endow the biosensor with enhanced sensitivity for target pathogen. The fluorescence biosensor demonstrates a wide linear response to P. aeruginosa in the concentration range of 10 1 –10 7 cfu mL −1 with acceptable selectivity . The limit of detection is calculated to be 1 cfu mL −1 . The whole detection process can be finished in 1.5 h. The feasibility of the fabricated biosensor is verified by successful determination of P. aeruginosa in skim milk, orange juice, and popsicle samples. The biosensor provides an alternative and attractive platform for rapid and sensitive detection of bacteria in food products.
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FOOD MICROBIOLOGY
·
2025
·
IF 4.6
Jiashi Li,Zhong Lu,Xiaoli Zeng,Hanxiao Zhang,Haixia Lu,Lifang Feng,Junli Zhu
Quorum quenching through natural and nontoxic N -acyl homoserine lactonase (AHL-lactonase) has been regarded as a promising approach for inactivating QS-mediated bacterial spoilage. However, their poor catalytic performance remains a major challenge for practical application. To address these limitations, we developed an efficient rational design strategy for AHL lactonase AiiA to obtain a variant with high catalytic efficiency and a broad substrate spectrum, based on computer-aided structural analysis, molecular dynamics simulation, and energy calculation. Results showed that three highly flexible regions in AiiA were identified as vital sites to recognize and position different substrates, possessing high engineering potential. Among the obtained 10 mutants, AiiA A130T exhibited the strongest degradation against short-chain AHL (C 4 -HSL and C 6 -HSL), along with improved thermostability, compared to wild-type enzyme (AiiA WT ). In Pseudomonas fluorescens PF07, a majority of AHLs were quenched to undetectable levels by AiiA A130T , and the lactone ring of C 4 -HSL was verified to hydrolyze and produce form butyryl-L-homoserine. Its biofilm biomass, exopolysaccharides, exoprotein contents, and exoprotease activity were effectively repressed by 64.63 %, 48.86 %, 51.85 %, 61.50 % by AiiA A130T , respectively, in contrast with 46.51 %, 29.08 %, 23.55 %, 19.5 % by AiiA WT , without affecting bacterial growth. Moreover, the transcription levels of 16 crucial QS and biofilm-related genes in PF07 were dramatically downregulated ( P < 0.05), as evidenced by qRT-PCR. In contrast with the slight preservation for AiiA WT , AiiA A130T effectively retarded the fillet deterioration of large yellow croaker and extended their shelf life by 2 days. Overall, this study presents an efficient strategy for modifying AHL lactonase and yields a high-performance mutant, offering the application potential of AHL lactonase for controlling QS-mediated microbial spoilage of seafood.
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FISH & SHELLFISH IMMUNOLOGY
·
2025
·
IF 3.9
Meiqin Mao,Zhixia Zhuang,Xiaoru Wang,Huabin Huang,Jiaonan Zhang,Jiaolin Zhang,Qingpi Yan
Pseudomonas plecoglossicida is a significant pathogen in aquaculture, capable of infecting various teleost fish and causing visceral white spot disease, which leads to substantial economic losses. The PhoP/PhoQ two-component system plays a central role in virulence regulation in Gram-negative bacteria; however, its specific function in P. plecoglossicida remains unclear. To elucidate the role of the phoP gene in the pathogenicity of this bacterium, we used hybrid grouper ( Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) as an infection model to compare the pathogenicity and host immune responses among the wild-type (NZBD9), phoP deletion (Δ phoP ), and complemented (C-Δ phoP ) strains. In artificial infection experiments, the Δ phoP strain exhibited significantly attenuated virulence, with an LD 50 value of 4.082 × 10 4 , which was 13.7 times higher than that of the wild-type strain. Furthermore, the deletion of phoP reduced bacterial load in the spleen and alleviated histopathological damage in the spleen, head kidney, and intestine. RNA-seq analysis of spleen tissue at 4 days post-infection identified 1768 differentially expressed genes (DEGs), including 704 up-regulated and 1064 down-regulated genes. GO and KEGG enrichment analyses revealed that these DEGs were primarily involved in immune-related processes and pathways, including TLR signaling, NF-κB activation, PI3K-Akt signaling, cytokine-cytokine receptor interaction, and cell adhesion molecules. Temporal expression profiling via qRT-PCR demonstrated that key immune genes (including tlr1, tlr5 , tlr13 , traf5 , nf-κb , mcp1 , cd3 , and il10 ) were generally down-regulated or exhibited delayed and weakened activation in Δ phoP -infected fish, indicating a subdued and dysregulated immune response. These results suggest that the phoP gene is essential for maintaining full virulence in P. plecoglossicida , modulating host immunity by suppressing critical inflammatory and immune signaling pathways. Our study provides novel insights into the role of the PhoP/PhoQ system in host–pathogen interactions and lays a theoretical foundation for developing targeted control strategies against P. plecoglossicida infection in aquaculture.
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