查找使用阿拉丁产品的科研文献

Identification and characterization of a novel high-activity amylosucrase from Salinispirillum sp. LH10-3-1

Li Jing,Li Ziyi,Gong Hui,Ma Mengyi,Li Shuolei,Yang Huilin,Zhang Hailin,Liu Jianguo

Abstract In this study, a novel high-activity amylosucrase from Salinispirillum sp. LH10-3-1 (SaAS) was identified and characterized. The recombinant enzyme was determined as a monomer with a molecular mass of 75 kDa. SaAS protein exhibited the maximum total and polymerization activities at pH 9.0 and maximum hydrolysis activity at pH 8.0. The optimum temperature for total, polymerization, and hydrolysis activities were 40, 40, and 45 °C, respectively. Under the optimal pH and temperature, SaAS had a specific activity of 108.2 U/mg. SaAS also showed excellent salt tolerance and could retain 77.4% of its original total activity at 4.0 M NaCl. The addition of Mg 2+ , Ba 2+ , and Ca 2+ enhanced the total activity of SaAS. When the conversion of 0.1 M and 1.0 M sucrose was catalyzed at pH 9.0 and 40 °C for 24 h, the ratios of hydrolysis, polymerization, and isomerization reactions were 11.9:77.4:10.7 and 15.3:53.5:31.2, respectively. The α-arbutin yield of 60.3% was achieved from 20 mM sucrose and 5 mM hydroquinone catalyzed by SaAS. Key points • A novel amylosucrase from Salinispirillum sp. LH10-3-1 (SaAS) was characterized. • SaAS has the highest specific enzyme activity among all known amylosucrase. • SaAS has hydrolysis, polymerization, isomerization, and glucosyltransferase activities. Graphical Abstract

Biodegradation of polyester polyurethane by Cladosporium sp. P7: Evaluating its degradation capacity and metabolic pathways

Jiawei Liu,Qingyi Zeng,Huirui Lei,Kaiyuan Xin,Anming Xu,Ren Wei,Ding Li,Jie Zhou,Weiliang Dong,Min Jiang

Microorganisms capable of decomposing polyurethane (PU) and other plastics have the potential to be used in bio-recycling processes. In this study, 20 PU-degrading strains were isolated, including 11 bacteria and 9 fungi, using a synthesized poly(1,4-butylene adipate)-based PU (PBA-PU) as the screening substrate. Three PU substrates with increasing structure complexities were used for a thorough evaluation of microbial degradation capacity: Impranil® DLN-SD, PBA-PU film and PU foam waste. After 4 days, the best fungal PBA-PU degrader, Cladosporium sp. P7, could degrade 94.5% of Impranil® DLN-SD. After 28 days of cultivation, 32.42% and 43.91% of solid PBA-PU film was converted into soluble small molecules when used as the sole carbon source or in a medium with other co-carbon sources, respectively. Accordingly, the weight loss of PU foam waste after 15 days was 15.3% for the sole carbon condition and 83.83% for the co-carbon conditions. Furthermore, PBA-PU was used for metabolic pathway analysis because of its known composition and chemical structure. Six metabolites were identified during the degradation process of PBA-PU, including adipic acid (AA), 1,4-butanediol (BDO), and 4,4’-methylenedianiline (MDA), which can also be used as the sole carbon source to grow the fungal strain P7, resulting in the discovery of two MDA metabolites during the cultivation processes. Based on the presence of these eight metabolites, we hypothesized that PBA-PU is first depolymerized by the fungal strain P7 via ester and urethane bond hydrolysis , followed by intracellular metabolism and mineralization of the three monomers to CO 2 and H 2 O.

Characterization and Hydrocarbon Degradation Potential of Variovorax sp. Strain N23 Isolated from the Antarctic Soil

Jinyan Liu,Zhisong Cui,Tong Hao,Yingchao Li,Xiao Luan,Ke Feng,Li Zheng

Increasing pollution has significantly threatened the Antarctic ecosystem. The contamination of hydrocarbons has drawn a considerable amount of attention owing to their toxicity, recalcitrance, and persistence. Considering the Antarctic Treaty, only indigenous species are allowed to bioremediate the contaminated environment. However, the knowledge of the ecological role, physiology, function, and genomics of endemic hydrocarbon consumers is still limited. Here, we investigated the dynamics of phenanthrene-consuming communities derived from the Antarctic soil and found thatVariovorax, Rhodocyclaceae, andHydrogenophagawere differentiated in all the phenanthrene-consuming subcultures. We isolated a pure culture of the key hydrocarbon consumerVariovoraxsp. strain N23. Moreover, the result of the polyphasic approach suggested that strain N23 represents a novel species of the genusVariovorax. In addition, the genomic characteristics of this strain revealed incomplete degradation pathways for diverse hydrocarbons. Overall, this study reveals the relatively weak hydrocarbon-degrading potential of the indigenous bacteria and suggests the need for more careful protection of the Antarctic ecosystem.Keywords:polycyclic aromatic hydrocarbons;psychrophilic bacteria;genomics;chemotaxis;biodegradation

Two New Phenylhydrazone Derivatives from the Pearl River Estuary Sediment-Derived Streptomyces sp. SCSIO 40020

Wei Liu,Liang Ma,Liping Zhang,Yuchan Chen,Qingbo Zhang,Haibo Zhang,Weimin Zhang,Changsheng Zhang,Wenjun Zhang

Two new phenylhydrazone derivatives and one new alkaloid, penzonemycins A–B (1–2) and demethylmycemycin A (3), together with three known compounds including an alkaloid (4) and two sesquiterpenoids (5–6), were isolated from theStreptomycessp. SCSIO 40020 obtained from the Pearl River Estuary sediment. Their structures and absolute configurations were assigned by 1D/2D NMR, mass spectroscopy and X-ray crystallography. Compound1was evaluated in four human cancer cell lines by the SRB method and displayed weak cytotoxicity in three cancer cell lines, with IC50values that ranged from 30.44 to 61.92 µM, which were comparable to those of the positive control cisplatin. Bioinformatic analysis of the putative biosynthetic gene cluster indicated a Japp–Klingemann coupling reaction involved in the hydrazone formation of1and2.Keywords:penzonemycins;phenylhydrazones;Streptomycessp.;Japp–Klingemann coupling reaction;marine natural products

Isolation of a diazinon-degrading strain Sphingobium sp. DI-6 and its novel biodegradation pathway

Wang Guangli,Li Xiang,Zheng Jiaxin,Li Xuedong,Bai Lingling,Yue Wenlong,Jiang Li

Diazinon is one of the most widely used organophosphate insecticides, one that is frequently detected in the environment. In this study, a diazinon-degrading bacterium, DI-6, previously isolated from diazinon-contaminated soil in China has been subsequently identified as Sphingobium sp. on the basis of its physiological and biochemical characteristics, as well as by virtue of a comparative analysis of 16S rRNA gene sequences. This strain is capable of using diazinon as its sole carbon source for growth and was able to degrade 91.8% of 100 mg L–1 diazinon over a 60-h interval. During the degradation of diazinon, the following seven metabolites were captured and identified by gas chromatography/mass spectrometry (GC–MS) analysis: diazoxon, diazinon aldehyde, isopropenyl derivative of diazinon, hydroxyethyl derivative of diazinon, diazinon methyl ketone, O-[2-(1-hydroxyethyl)-6-methylpyrimidin-4-yl] O-methyl O-hydrogen phosphorothioate, and O-(6-methyl pyrimidin-4-yl) O,O-dihydrogen phosphorothioate. Based on these metabolites, a novel microbial biodegradation pathway of diazinon by Sphingobium sp. DI-6 is proposed. This research provides potentially useful information for the application of the DI-6 strain in bioremediation of diazinon-contaminated environments.

New insights into lincomycin biodegradation by Conexibacter sp. LD01: Genomics characterization, biodegradation kinetics and pathways

Huaxin Lei,Jiayu Zhang,Jin Huang,Dengjin Shen,Yin Li,Rui Jiao,Renxin Zhao,Xiaoyan Li,Lin Lin,Bing Li

The aerobic, lincomycin-degrading bacterial strain Conexibacter sp . LD01, belonging to the phylum Actinobacteria, was isolated from activated sludge . Both second- and third-generation sequencing technologies were applied to uncover the genomic characterization and high-quality genome with 99.2% completeness and 2.2% contamination was obtained. The biodegradation kinetics of lincomycin fit well with the modified Gompertz model ( R 2 > 0.97). Conexibacter sp . LD01 could subsist with lincomycin as the sole source of carbon, nitrogen, and energy. When 500 mg/L of glucose was added as a co-substrate, the biodegradation rate improved significantly, whereas the addition of 500 mg/L sodium pyruvate had a slight inhibitory effect. Ammonia nitrogen was the best nitrogen source for Conexibacter sp . LD01 when growing and degrading lincomycin. In total, 17 metabolic products consisting of nine novel products were detected, and five biodegradation pathways, including N-demethylation, breakage of the amido bond, sulfoxidation, and oxidation of the pyrrolidine ring and propylamino chain, were proposed. This study significantly expands our understanding of the functional microorganisms and mechanism involved in lincomycin biodegradation at the phylum level.

A novel strategy for Klebsiella sp. to resist high salt and high phenol environmental stress

Jiejing Zhang,Chong Hu,Yu Wu,Jing Liang,Cesar Danilo Valle Exposito,Jianfeng Zhang

Isolating high-performance phenol degradation microorganisms with high salt tolerance and studying their resistance mechanisms are urgent issues. To address these issues, a typical bacteria ( Klebsiella sp. YP-1) with high salt and phenol tolerance was isolated. Its strategies for resisting high salt and high phenol stress were studied. The results indicated that Klebsiella sp. YP-1 was able to degrade 1000 mg/L phenol within 44 h at 70 g/L NaCl, which was faster than most microorganisms reported in the literature. Lyxose secreted by Klebsiella sp. YP-1 played an important role on assisting Klebsiella sp. YP-1 to resist stress. Lyxose increased phenol degradation rate by microorganisms due to its protection on cell membrane. Quantum chemical calculation results indicated that lyxose was more likely attacked by free radical than cell membrane. In addition, lyxose could bind to the cell membrane through hydrogen bonds. Thus, lyxose prevented reactive oxygen species from harming cell membranes. Moreover, lyxose has broad protective effect on microbial cell membranes. This study provides a novel idea for microorganisms to resist oxidative stresses.

Characterisation of Fusarium oxysporum f. sp. radicis-lycopersici in Infected Tomatoes in Inner Mongolia, China

Yongqing Yang,Yong Wang,Jing Gao,Zhidan Shi,Wenjin Chen,Haiyan Huangfu,Zhengnan Li,Yan Liu

Fusarium crown and root rot (FCRR), caused by Fusarium oxysporum f. sp. radicis-lycopersici (FORL), is an economically important disease that affects tomatoes worldwide and has become more prevalent in China in recent years. In 2021 and 2022, tomato plants in greenhouses in Hohhot, Inner Mongolia, were observed showing symptoms of stunting, premature loss of lower leaves, and root rot. Fungal pathogens were isolated from 20 infected tomato plants and identified based on morphological observation and DNA sequencing. Twelve isolates were consistently identified as Fusarium oxysporum f. sp. radicis - lycopersici (FORL) via an analysis of the ITS , TEF- 1α , and pgx4 genes. This is the first report of FORL in Inner Mongolia, China. The isolates were examined for their pathogenicity by inoculating them on tomatoes, eggplants, peppers, and chickpeas. The fungicide sensitivity of the isolates was determined. Effective concentrations for 50% growth inhibition (EC 50 ) were measured using seven fungicides. The EC 50 values of tebuconazole and prochloraz were <1.0 μg·mL −1 , exhibiting the most effective inhibition among the fungicides tested. Additionally, FORL resistance screening of tomato germplasms was performed. One tomato variety was resistant to FORL, and the remaining 43 germplasm lines showed various levels of resistance. The rates of highly susceptible, moderately susceptible, susceptible, and moderately resistant germplasms accounted for 29.55%, 22.73%, 40.91%, and 4.55% of the 44 germplasms tested, respectively.

Degradation of low-density polyethylene by the bacterium Rhodococcus sp. C-2 isolated from seawater

Zhen Rong,Zhi-Hao Ding,Yue-Hong Wu,Xue-Wei Xu

Low-density polyethylene (LDPE), which accounts for 20% of the global plastic production, is discharged in great quantities into the ocean, threatening marine life and ecosystems. Marine microorganisms have previously been reported to degrade LDPE plastics; however, the exploration of strains and enzymes that degrade LDPE is still limited. Here, an LDPE-degrading bacterium was isolated from seawater of the Changjiang Estuary, China and identified as Rhodococcus sp. C-2, the relative abundance of which was dramatically enhanced during PE-degrading microbial enrichment. The strain C-2 exhibited the degradation of LDPE films, leading to their morphological deterioration, reduced hydrophobicity and tensile strength, weight loss, as well as the formation of oxygen-containing functional groups in short-chain products. Sixteen bacterial enzymes potentially involved in LDPE degradation were screened using genomic, transcriptomic, and degradation product analyses. Thereinto, the glutathione peroxidase GPx with exposed active sites catalyzed the LDPE depolymerization with the cooperation of its dissociated superoxide anion radicals. Furthermore, an LDPE degradation model involving multiple enzymes was proposed. The present study identifies a novel PE-degrading enzyme (PEase) for polyethylene bioremediation and promotes the understanding of LDPE degradation.

Characterization of a novel aromatic ring-hydroxylating oxygenase, NarA2B2, from thermophilic Hydrogenibacillus sp. strain N12

Lihua Guo,Xingyu Ouyang,Weiwei Wang,Yiqun Huang,Xiaoyu Qiu,Ping Xu,Hongzhi Tang

Unveiling the regulatory mechanisms of salicylate degradation gene cluster cehGHIR4 in Rhizobium sp. strain X9

Zhijian Ke,Qian Zhu,Mingliang Zhang,Siyuan Gao,Mingli jiang,Yidong Zhou,Jiguo Qiu,Minggen Cheng,Xin Yan,Jinbo Wang,Qing Hong

Identification and Characterization of Novel Malto-Oligosaccharide-Forming Amylase AmyCf from Cystobacter sp. Strain CF23

Jihong Wang,Lei Zhang,Peiwen Wang,Jinhui Lei,Lingli Zhong,Lei Zhan,Xianfeng Ye,Yan Huang,Xue Luo,Zhongli Cui,Zhoukun Li

Malto-oligosaccharides (MOSs) from starch conversion is advantageous for food and pharmaceutical applications. In this study, an efficient malto-oligosaccharide-forming α-amylase AmyCf was identified from myxobacterCystobactersp. strain CF23. AmyCf is composed of 417 amino acids with N-terminal 41 amino acids as the signal peptide, and conserved glycoside hydrolase family 13 (GH13) catalytic module and predicted C-terminal domain with β-sheet structure are also identified. Phylogenetic and functional analysis demonstrated that AmyCf is a novel member of GH13_6 subfamily. The special activity of AmyCf toward soluble starch and raw wheat starch is 9249 U/mg and 11 U/mg, respectively. AmyCf has broad substrate specificity toward different types of starches without requiring Ca2+. Under ideal circumstances of 60 °C and pH 7.0, AmyCf hydrolyzes gelatinized starch into maltose and maltotriose and maltotetraose as the main hydrolytic products with more than 80% purity, while maltose and maltotriose are mainly produced from the hydrolysis of raw wheat starch with more than 95% purity. The potential applicability of AmyCf in starch processing is highlighted by its capacity to convert gelatinized starch and raw starch granules into MOSs. This enzymatic conversion technique shows promise for the low-temperature enzymatic conversion of raw starch.Keywords:Malto-oligosaccharides;Cystobacter;gelatinized starch;enzymatic conversion;raw starch