Degradation of p-benzyloxyphenol by Acinetobacter sp.

Abstract Acinetobacter sp. utilized p -benzyloxyphenol as sole carbon source and degraded it to p -hydroxybenzaldehyde, p -hydroxybenzoic acid, protocatechuic acid and catechol. The intermediates were identified by paper chromatography, TLC, IR, GC and HPLC. Acinetobacter sp. produced protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase during the degradation of p -benzoloxyphenol.     

不动杆菌（Acinetobacters sp）51—2降解乙腈的研究

A strain of Acinetobacter sp. 51-2 was capable of degrading acetonitrile and utilizing various nitrile compounds, such as propionitrile, butyronitrile, acrylonitrile and so on. The ability and speed of degrading acetonitrile were quite strong and fast. Strain 51-2 could degrade 25 g/L acetonitrile in 48 h by adapted cells. The efficiency of degrading acetonitrile was closely related to the conditions of culturing bacterial cells. The reaction temperature and present metals appeared to have a little effect on degradation of acetonitrile.     

Degradation of lignin and lignin derivatives by Acinetobacter sp.

An Acinetobacter sp. utilized 2-methoxy-4-formylphenoxyacetic acid, dehydrodivanillyl alcohol, dehydrodiisoeugenol and conidendrin as sole carbon source. It also degraded ¹⁴C-labelled DHP lignin and teakwood lignin. Vanillic acid, protocatechuic acid and catechol were separated from 2-methoxy-4-formylphenoxyacetic acid grown cultures. Both protocatechuic acid and catechol were formed from dehydrodivanillyl alcohol, dehydrodiisoeugenol and conidendrin. On the dimeric lignin model substances this Acinetobacter sp. produced protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase.     

Microbial degradation of lipid by Acinetobacter sp. strain SOD-1

Acinetobacter sp. strain SOD-1, capable of rapidly degrading salad oil, was isolated from soil. Strain SOD-1 showed good growth and degraded 68.7+/-2.7 and 83.0% of an initial 3000 ppm salad oil suspension in 24 h at 20 degrees C and pH 7.0 and at 35 degrees C and pH 8.0, respectively. The degradation rate depended on pH, temperature, phosphate concentration, and initial cell density.     

Laccase-mediated detoxification of phenolic compounds.

The ability of a polyphenoloxidase, the laccase of the fungus Rhizoctonia praticola, to detoxify phenolic pollutants was examined. The growth of the fungus could be inhibited by phenolic compounds, and the effective concentration was dependent on the substituents of the phenol. A toxic amount of a phenolic compound was added to a fungal growth medium in the presence or absence of a naturally occurring phenol, and half of the replicates also received laccase. The medium was then inoculated with R. praticola, and the levels of phenols in the medium were monitored by high-performance liquid chromatography analysis. The addition of the laccase reversed the inhibitory effect of 2,6-xylenol, 4-chloro-2-methylphenol, and p-cresol. Other compounds, e.g., o-cresol and 2,4-dichlorophenol, were detoxified only when laccase was used in conjunction with a natural phenol such as syringic acid. The toxicity of p-chlorophenol and 2,4,5-trichlorophenol could not be overcome by any additions. The ability of the laccase to alter the toxicity of the phenols appeared to be related to the capacity of the enzyme to decrease the levels of the parent compound by transformation or cross-coupling with another phenol.     

多功能过氧化物酶介导Mn(III)络合体系对酚类化合物的氧化降解

【背景】酚类化合物是环境中主要的水体污染物之一。多功能过氧化物酶(versatile peroxidase,VP)介导的Mn (III)-有机酸络合体系具有较高的氧化还原电势,在酚类有机污染物降解方面具有巨大潜力。【目的】探究VP介导的Mn (III)-有机酸络合体系降解酚类化合物的能力,为酚类化合物的降解提供新的思路和方法。【方法】研究选取了糙皮侧耳(Pleurotus eryngii)来源的多功能过氧化物酶(PeVP),采用包涵体复性的方法获得了PeVP活性蛋白,并对重组PeVP进行酶学性质研究及Mn (III)络合体系反应条件优化,进而探究Mn (III)络合体系对酚类污染物的氧化降解能力。【结果】确定了PeVP包涵体复性最佳条件为：pH 9.5、10%甘油、0.5 mol/L尿素、0.5 mmol/L氧化型谷胱甘肽(glutathione oxidized,GSSG)、0.1 mmol/L二硫苏糖醇(dithiothreitol,DTT)、0.1 mmol/L乙二胺四乙酸(ethylenediamine tetraacetic acid,EDTA)、5 mmol/L CaCl₂、5µmol/L羟高铁血红素(hematin),4℃静置透析24 h,最后5µmol/L hematin孵育12 h。通过对PeVP介导的Mn (III)-有机酸络合体系优化,确定了最优反应条件为：75 mmol/L苹果酸缓冲液(pH 4.5)、6 mmol/L Mn²⁺和0.2 mmol/L H₂O₂。在上述条件下,探究了络合体系对2,2-丁香醛连氮-双-3-乙基苯并噻唑啉-6-磺酸[2,2ʹ-azinobis-(3-ethylbenzthiazoline-6-sulphonate),ABTS]、2,6-二甲氧基苯酚(2,6-dimethoxyphenol,DMP)、愈创木酚和丁香醛连氮4种酚类模式底物的催化活性,发现在pH 4.5条件下,络合体系对酚类模式底物的氧化活性可达到PeVP直接氧化活性的1.5−7.5倍,并且在16 h的酶解过程中,苯酚、对苯二酚、间苯二酚和对硝基苯酚的平均降解速率分别为10.91、10.69、6.50和5.71 mg/(L·h),推测Mn (III)-有机酸络合物对酚类底物的氧化降解是通过夺取酚类底物的电子形成酚类自由基中间体,自由基中间体经过电子重排和C−C键的断裂,最终导致酚类物质的氧化降解。【结论】在弱酸(pH 4.5)条件下PeVP介导的Mn (III)-苹果酸络合体系对酚类污染物具备较强的氧化能力,这为酚类有机污染物提供了新的生物解决方案。     

Cometabolism of 3,4-dichlorobenzoate by Acinetobacter sp. strain 4-CB1.

When Acinetobacter sp. strain 4-CB1 was grown on 4-chlorobenzoate (4-CB), it cometabolized 3,4-dichlorobenzoate (3,4-DCB) to 3-chloro-4-hydroxybenzoate (3-C-4-OHB), which could be used as a growth substrate. No cometabolism of 3,4-DCB was observed when Acinetobacter sp. strain 4-CB1 was grown on benzoate. 4-Carboxyl-1,2-benzoquinone was formed as an intermediate from 3,4-DCB and 3-C-4-OHB in aerobic and anaerobic resting-cell incubations and was the major transient intermediate found when cells were grown on 3-C-4-OHB. The first dechlorination step of 3,4-DCB was catalyzed by the 4-CB dehalogenase, while a soluble dehalogenase was responsible for dechlorination of 3-C-4-OHB. Both enzymes were inducible by the respective chlorinated substrates, as indicated by oxygen uptake experiments. The dehalogenase activity on 3-C-4-OHB, observed in crude cell extracts, was 109 and 44 nmol of 3-C-4-OHB min-1 mg of protein-1 under anaerobic and aerobic conditions, respectively. 3-Chloro-4-hydroxybenzoate served as a pseudosubstrate for the 4-hydroxybenzoate monooxygenase by effecting oxygen and NADH consumption without being hydroxylated. Contrary to 4-CB metabolism, the results suggest that 3-C-4-OHB was not metabolized via the protocatechuate pathway. Despite the ability of resting cells grown on 4-CB or 3-C-4-OHB to carry out all of the necessary steps for dehalogenation and catabolism of 3,4-DCB, it appeared that 3,4-DCB was unable to induce the necessary 4-CB dehalogenase for the initial p-dehalogenation step.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of hexadecane partition by the growth medium of Acinetobacter sp.

The partition of n-hexadecane in the spent growth medium of Acinetobacter sp. HOI-N was determined by measuring the increase in the relative aqueous solubility of ³H-hexadecane as compared to controls. The amount of hexadecane partitioned was proportional to the protein concentration. The specific solubility of hexadecane (nmol/mg protein) was analyzed by least-squares fitting yielding an average slope of 0.6 with a standard deviation of 0.3, indicating either nonequilibrium of hexadecane or physical aggregation of protein. The amount of hexadecane partitioned was concentration dependent yielding optically clear microemulsions at hexadecane concentrations of less than 1.4mM and macroemulsions at hexadecane concentrations of 1.4mM or greater. Preliminary results indicated that hexadecane and partitioned by a lipoprotein complex.     

Gene structures and regulation of the alkane hydroxylase complex in Acinetobacter sp. strain M-1

In the long-chain n-alkane degrader Acinetobacter sp. strain M-1, two alkane hydroxylase complexes are switched by controlling the expression of two n-alkane hydroxylase-encoding genes in response to the chain length of n-alkanes, while rubredoxin and rubredoxin ruductase are encoded by a single gene and expressed constitutively.     

Utilization of d-carnitine by Pseudomonas sp. AK 1

Abstract The degradation of chlorophenols by Alcaligenes eutrophus JMP134 (pJP4) was studied. The strain grew on 2,4,6-trichlorophenol or 2,4,6-tribromophenol as the sole carbon and energy source. Complete degradation of 2,4,6-trichlorophenol was confirmed by chloride release and gas chromatography analysis of supernatants from growth cultures. The 2,3,5-, 2,3,4-, 2,3,6-and 2,4,5-isomers of trichlorophenol did not support growth. However, up to 40% of 2,4,5-trichlorophenol was mineralized during growth of A. eutrophus on chemostats fed with either phenol (0.4 mM) or 2,4,6-trichlorophenol (0.4 mM) plus 2,4,5-trichlorophenol (0.1 mM). Growth on 2,4,6-trihalophenols was also observed in A. Eutrophus JMP222, the strain lacking pJP4, suggesting that this new degradative ability reported for A. eutrophus is not related to pJP4 encoded catabolic functions.     

Degradation of acyl-homoserine lactone molecules by Acinetobacter sp. strain C1010

A bacterium C1010, isolated from the rhizospheres of cucumbers in fields in Korea, degraded the microbial quorum-sensing molecules, hexanoyl homoserine lactone (HHSL), and octadecanoyl homoserine lactone (OHSL). Morphological characteristics and 16S rRNA sequence analysis identified C1010 as Acinetobacter sp. strain C1010. This strain was able to degrade the acyl-homoserine lactones (AHLs) produced by the biocontrol bacterium, Pseudomonas chlororaphis O6, and a phytopathogenic bacterium, Burkholderia glumae. Co-cultivation studies showed that the inactivation of AHLs by C1010 inhibited production of phenazines by P. chlororaphis O6. In virulence tests, the C1010 strain attenuated soft rot symptom caused by Erwinia carotovora ssp. carotovora. We suggest Acinetobacter sp. strain C1010 could be a useful bacterium to manipulate biological functions that are regulated by AHLs in various Gram-negative bacteria.     

Cometabolism of 3,4-dichlorobenzoate by Acinetobacter sp. strain 4-CB1

When Acinetobacter sp. strain 4-CB1 was grown on 4-chlorobenzoate (4-CB), it cometabolized 3,4-dichlorobenzoate (3,4-DCB) to 3-chloro-4-hydroxybenzoate (3-C-4-OHB), which could be used as a growth substrate. No cometabolism of 3,4-DCB was observed when Acinetobacter sp. strain 4-CB1 was grown on benzoate. 4-Carboxyl-1,2-benzoquinone was formed as an intermediate from 3,4-DCB and 3-C-4-OHB in aerobic and anaerobic resting-cell incubations and was the major transient intermediate found when cells were grown on 3-C-4-OHB. The first dechlorination step of 3,4-DCB was catalyzed by the 4-CB dehalogenase, while a soluble dehalogenase was responsible for dechlorination of 3-C-4-OHB. Both enzymes were inducible by the respective chlorinated substrates, as indicated by oxygen uptake experiments. The dehalogenase activity on 3-C-4-OHB, observed in crude cell extracts, was 109 and 44 nmol of 3-C-4-OHB min-1 mg of protein-1 under anaerobic and aerobic conditions, respectively. 3-Chloro-4-hydroxybenzoate served as a pseudosubstrate for the 4-hydroxybenzoate monooxygenase by effecting oxygen and NADH consumption without being hydroxylated. Contrary to 4-CB metabolism, the results suggest that 3-C-4-OHB was not metabolized via the protocatechuate pathway. Despite the ability of resting cells grown on 4-CB or 3-C-4-OHB to carry out all of the necessary steps for dehalogenation and catabolism of 3,4-DCB, it appeared that 3,4-DCB was unable to induce the necessary 4-CB dehalogenase for the initial p-dehalogenation step.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolism of symmetrical dialkyl ethers by Acinetobacter sp. HO1-N

The growth of Acinetobacter species HO1-N on a homologous series of dialkyl ethers yielded characteristic cellular and extracellular ether fatty acids. Microbial growth on diheptyl ether resulted in the appearance of 7-n-heptoxy-1-n-heptanoic acid as a cellular fatty acid and 2-n-heptoxy-1-acetic acid as the sole extracellular fatty acid. The oxidation of dinonyl ether and didecyl ether by Acinetobacter resulted in the extracellular accumulation of 2-n-nonoxy-acetic acid and 2-n-decoxy-1-acetic acid, respectively. The 16-carbon ether fatty acid, 6-n-decoxy-1-n-hexanoic acid, was identified as a major cellular fatty acid in didecyl ether-grown cells. The extracellular ether fatty acids accumulated in an inverse relationship to the disappearance of the dialkyl ether and appeared to represent end products of metabolism. The carbon and energy required for cellular growth and metabolism resided in the terminal 5-carbons of diheptyl ether, 7-carbons of dinonyl ether and 8-carbons of didecyl ether. Glutarate, adipate, pimelate and suberate were identified from cells grown at the expense of diheptyl, dioctyl, dinonyl and didecyl ether, respectively, suggesting a role for dibasic acids as metabolic intermediates. A new and novel mechanism for the metabolism of symmetrical dialkyl ethers is suggested. Terminal methyl group oxidation of the dialkyl ether results in the formation of an alkoxy-fatty acid followed by an internal carbon-carbon scission reaction 2-carbons removed from the oxygen atom. The resulting endproducts are alkoxyacetic acid and the corresponding dibasic acid.Non-Standard Abbreviations TLC Thin Layer Chromatography - PS-DEGS · PS Diethylene glycol succinate - DHE Diheptyl ether - DOE Dioctyl ether - DNE Dionyl ether - DDE Didecyl ether     

Inhibition of aflatoxin biosynthesis by phenolic compounds

The phenolic compounds acetosyringone, syringaldehyde and sinapinic acid inhibited the biosynthesis of aflatoxin B1 (AFB1) by A. flavus. Acetosyringone was the most active among the three compounds, inhibiting aflatoxin level by 82% at 2 m moll-1. The synthesis and accumulation of norsolorinic acid, an aflatoxin biosynthetic intermediate, was also inhibited. These results suggest that at least one step early in the AFB1 biosynthetic pathway is inhibited by the phenolics.     

Inhibition of enzymatic cellulolysis by phenolic compounds

Phenolics derived from lignin and other plant components can pose significant inhibition on enzymatic conversion of cellulosic biomass materials to useful chemicals. Understanding the mechanism of such inhibition is of importance for the development of viable biomass conversion technologies. In native plant cell wall, most of the phenolics and derivatives are found in polymeric lignin. When biomass feedstocks are pretreated (prior to enzymatic hydrolysis), simple or oligomeric phenolics and derivatives are often generated from lignin modification/degradation, which can inhibit biomass-converting enzymes. To further understand how such phenolic substances may affect cellulase reaction, we carried out a comparative study on a series of simple and oligomeric phenolics representing or mimicking the composition of lignin or its degradation products. Consistent to previous studies, we observed that oligomeric phenolics could exert more inhibition on enzymatic cellulolysis than simple phenolics. Oligomeric phenolics could inactivate cellulases by reversibly complexing them. Simple and oligomeric phenolics could also inhibit enzymatic cellulolysis by adsorbing onto cellulose. Individual cellulases showed different susceptibility toward these inhibitions. Polyethylene glycol and tannase could respectively bind and degrade the studied oligomeric phenolics, and by doing so mitigate the oligomeric phenolic's inhibition on cellulolysis.     

Biotransformation of phenolic compounds by Bacillus aryabhattai

Bioprocess and Biosystems Engineering - Phenolic compounds could pose environmental problems if they are in excess, although they could be a renewable resource of substances with industrial...     

Delineation of a novel environmental phylogroup of the genus Acinetobacter encompassing Acinetobacter terrae sp. nov., Acinetobacter terrestris sp. nov. and three other tentative species

This study aimed to define the taxonomic position and structure of a novel, taxonomically unique group of 26 Acinetobacter strains, provisionally designated Taxon 24 (T24). The strains were recovered from soil and freshwater ecosystems (n = 21) or animals (n = 5) in Czechia, Scotland, Germany, the Netherlands and Turkey between 1993 and 2015. They were non-glucose-acidifying, nonhemolytic, nonproteolytic, growing at 32 °C and on acetate and ethanol as single carbon sources, but not on 4-hydroxybenzoate and mostly not at 37 °C. Their whole-genome sequences were 3.0–3.7 Mb in size, with GC contents of 39.8–41.3%. Based on core genome phylogenetic analysis, the 26 strains formed a distinct clade within the genus Acinetobacter, with strongly supported subclades termed T24A (n = 11), T24B (n = 8), T24C (n = 2), T24D (n = 3) and T24E (n = 2). The internal genomic ANIb values for these subclades were >94.8%, while the ANIb values between them were <92.5%. The results of MALDI-TOF MS-based analyses agreed with this classification. The five subclades differed from each other in the results of one to six carbon source assimilation tests. Given the genomic and phenotypic distinctness, internal coherence, numbers of available strains and geographically diverse origin of T24A and T24B, we propose the names Acinetobacter terrae sp. nov. and Acinetobacter terrestris sp. nov. for these two taxa, respectively. The type strains are ANC 4282^v (= CCM 8986^T = CCUG 73811^T = CNCTC 8082^T) and ANC 4471^T (= CCM 8985^T = CCUG 73812^T = CNCTC 8093^T), respectively. We conclude that these two species together with the other T24 strains represent a widely dispersed Acinetobacter clade primarily associated with terrestrial ecosystems.