Degradation of d-Biotin by Microorganisms

For the classical solution synthesis of human epidermal growth factor (h-EGF), five protected peptide derivatives, Boc-Leu-Asp(OcHex)-Lys(Cl-Z)-Tyr(Br-Z)-Ala-OH (5), Boc-Val-Cys(MeBzl)-Met-Tyr(Br-Z)-Ile-Glu(OcHex)-Ala-OH (12), Boc-Tyr(Br-Z)-Cys(MeBzl)-Leu-His-Asp(OcHex)-Gly-OH (18), Boc-Cys(MeBzl)-Pro-Leu-Ser(Bzl)-His-Asp(OcHex)-Gly-O H (23) and Boc-Asn-Ser(Bzl)-Asp(OcHex)-Ser(Bzl)-Glu(OcHex)-OH (28) were synthesized to build up the sequence corresponding to 1–30.     

Effect of Zytron and Its Degradation Products on Soil Microorganisms

There was no adverse effect of Zytron, o-2,4-dichlorophenyl o-methyl isopropyl phosphoramidothioate, a herbicide, upon molds, actinomycetes, and soil bacteria in field plots, or upon selected soil microorganisms in model systems. 2,4-Dichlorophenol, a degradation product, was found to be toxic at levels above 10 ppm to molds, but levels this high were not found in soil from treated plots. Aspergillus clavatus degraded both Zytron and 2,4-dichlorophenol. Sodium o-methyl isopropyl phosphoramidothioate, another degradation product of Zytron, stimulated the growth of a species of Penicillium.     

Phosphonates and Their Degradation by Microorganisms

Phosphonates are a class of organophosphorus compounds characterized by a chemically stable carbon-to-phosphorus (C–P) bond. Wide occurrence of phosphonates among xenobiotics polluting the environment has aroused interest in pathways and mechanisms of their biodegradation. Only procaryotic microorganisms and the lower eucaryotes are capable of phosphonate biodegradation via several pathways. Destruction of the non activated C–P bond by the C–P lyase pathway is of fundamental importance, and understanding of the process is a basic problem of biochemistry and physiology of microorganisms. This review offers analysis of available data on phosphonate degrading microorganisms, degradation pathways, and genetic and physiological regulation of this process.     

Studies on Degradation of d-Biotin by Microorganisms

During the course of investigations on the metabolism of d-biotin by microorganisms, the authors have found that a strain belonging to Endomycopsis effectively converted d-biotin into unknown biotin vitamers. The unknown biotin vitamers formed were isolated in crystalline form from the culture filtrate of a strain of Endomycopsis species and characterized as bisnorbiotin and bisnorbiotin sulfoxide by their physico-chemical and biological properties. The isolated vitamers were shown to support the growth of Bacillus subtilis, but not of Saccharomyces cerevisiae and of Lactobacillus arabinosus. The degradative pathway of d-biotin in microorganisms was also discussed.     

Studies on Degradation of d-Biotin by Microorganisms

During the course of our investigations on the metabolism of d-biotin by microorganism, it has been found that some strains of fungi belonging to the genera Rhodotorula, Penicillium and Endomycopsis, are able to degrade d-biotin oxidatively into various biotin vitamers. The present work was undertaken to characterize these vitamers. The vitamers formed were separated by the ion exchange column chromatography, into Fraction A (d-biotin sulfoxide), Fraction B (unknown vitamer II), Fraction C (d-biotin) and Fraction D (unknown vitamer I). Rf values of vitamer I and vitamer II were found to be different from those of the known biotin vitamers. The vitamers I and II did not support the growth of Lactobacillus arabinosus and Saccharomyces cerevisiae, but did support that of Bacillus subtilis. This degradation reaction occurred rather favorably in high aerobic condition.     

Degradation of chlorinated pesticide DDT by litter-decomposing basidiomycetes

One hundred and two basidiomycete strains (93 species in 41 genera) that prefer a soil environment were examined for screening of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) biodegradation. Three strains within two litter-decomposing genera, Agrocybe and Marasmiellus, were selected for their DDT biotransformation capacity. Eight metabolites; 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), two monohydroxy-DDTs, monohydroxy-DDD, 2,2-dichloro-1,1-bis(4-chlorophenyl)ethanol, putative 2,2-bis(4-chlorophenyl)ethanol and two unidentified compounds were detected from the culture with Marasmiellus sp. TUFC10101. A P450 inhibitor, 1-ABT, inhibited the formation of monohydroxy-DDTs and monohydroxy-DDD from DDT and DDD, respectively. These results indicated that oxidative pathway which was catalyzed by P450 monooxygenase exist beside reductive dechlorination of DDT. Monohydroxylation of the aromatic rings of DDT (and DDD) by fungal P450 is reported here for the first time.     

Biochemical and Molecular Basis of Pesticide Degradation by Microorganisms

Abstract

Fungal arachidonic acid (ARA)-rich oil is an important microbial oil that affects diverse physiological processes that impact normal health and chronic disease. In this article, the historic developments and technological achievements in fungal ARA-rich oil production in the past several years are reviewed. The biochemistry of ARA, ARA-rich oil synthesis and the accumulation mechanism are first introduced. Subsequently, the fermentation and downstream technologies are summarized. Furthermore, progress in the industrial production of ARA-rich oil is discussed. Finally, guidelines for future studies of fungal ARA-rich oil production are proposed in light of the current progress, challenges and trends in the field.     

Diversity of the Degradation of Panthenol by Microorganisms

Several microorganisms isolated from soil were found to grow in the medium containing panthenol. The results of the investigation of the degradative metabolism of this compound demonstrated that there are two different inducible pathways.

Strain 1041 produced 3-aminopropanol and β-alanine when grown with panthenol. 3-Aminopropanol plus pantoate, as well as panthenol, supported the growth of induced culture. Both washed cells and cell extract of the organism also produced 3-aminopropanol, which was then oxidized to β-alanine. No oxidation of panthenol to pantothenic acid was observed. Isolation and identification of the products were performed. These results led to the conclusion that panthenol is hydrolyzed to pantoic acid and 3-aminopropanol as the first step, which is then followed by oxidation to β-alanine.

Strain 1091 produced pantothenic acid, but not 3-aminopropanol, from panthenol. 3-Aminopropanol plus pantoate did not support the growth of the induced culture. No degradation of 3-aminopropanol was observed. Isolation and identification of pantothenic acid and a 3-methyl-2-benzothiazolone hydrazone derivative of the aldehyde form panthenol were performed. From the results, it was confirmed that panthenol is first oxidized to pantothenic acid, which is then hydrolyzed to β-alanine and pantoic acid.

Panthenol was also oxidized to pantothenic acid by Bacillus roseus AKU 0208. The enzyme was not induced in the presence of panthenol.     

Anaerobic Phenol Degradation by Microorganisms of Swine Manure

Swine manure contains diverse groups of aerobic and anaerobic bacteria. An anaerobic bacterial consortium containing sulfate-reducing bacteria (SRB) and acetate-utilizing methanogenic bacteria was isolated from swine manure. This consortium used phenol as its sole source of carbon and converted it to methane and CO₂. The sulfate-reducing bacterial members of the consortium are the incomplete oxidizers, unable to carry out the terminal oxidation of organic substrates, leaving acetic acid as the end product. The methanogenic bacteria of the consortium converted the acetic acid to methane. When a methanogen inhibitor was used in the culture medium, phenol was converted to acetic acid by the SRB, but the acetic acid did not undergo further metabolism. On the other hand, when the growth of SRB in the consortium was suppressed with a specific SRB inhibitor, namely, molybdenum tetroxide, the phenol was not degraded. Thus, the metabolic activities of both the sulfate-reducing bacteria and the methanogenic bacteria were essential for complete degradation of phenol. Received: 31 January 1997 / Accepted: 7 March 1997     

Degradation of Phthalate and Di-(2-Ethylhexyl)phthalate by Indigenous and Inoculated Microorganisms in Sludge-Amended Soil

The metabolism of phthalic acid (PA) and di-(2-ethylhexyl)phthalate (DEHP) in sludge-amended agricultural soil was studied with radiotracer techniques. The initial rates of metabolism of PA and DEHP (4.1 nmol/g [dry weight]) were estimated to be 731.8 and 25.6 pmol/g (dry weight) per day, respectively. Indigenous microorganisms assimilated 28 and 17% of the carbon in [¹⁴C]PA and [¹⁴C]DEHP, respectively, into microbial biomass. The rates of DEHP metabolism were much greater in sludge assays without soil than in assays with sludge-amended soil. Mineralization of [¹⁴C]DEHP to ¹⁴CO₂ increased fourfold after inoculation of sludge and soil samples with DEHP-degrading strain SDE 2. The elevated mineralization potential was maintained for more than 27 days. Experiments performed with strain SDE 2 suggested that the bioavailability and mineralization of DEHP decreased substantially in the presence of soil and sludge components. The microorganisms metabolizing PA and DEHP in sludge and sludge-amended soil were characterized by substrate-specific radiolabelling, followed by analysis of ¹⁴C-labelled phospholipid ester-linked fatty acids (¹⁴C-PLFAs). This assay provided a radioactive fingerprint of the organisms actively metabolizing [¹⁴C]PA and [¹⁴C]DEHP. The ¹⁴C-PLFA fingerprints showed that organisms with different PLFA compositions metabolized PA and DEHP in sludge-amended soil. In contrast, microorganisms with comparable ¹⁴C-PLFA fingerprints were found to dominate DEHP metabolism in sludge and sludge-amended soil. Our results suggested that indigenous sludge microorganisms dominated DEHP degradation in sludge-amended soil. Mineralization of DEHP and PA followed complex kinetics that could not be described by simple first-order equations. The initial mineralization activity was described by an exponential function; this was followed by a second phase that was described best by a fractional power function. In the initial phase, the half times for PA and DEHP in sludge-amended soil were 2 and 58 days, respectively. In the late phase of incubation, the apparent half times for PA and DEHP increased to 15 and 147 days, respectively. In the second phase (after more than 28 days), the half time for DEHP was 2.9 times longer in sludge-amended soil assays than in sludge assays without soil. Experiments with radiolabelled DEHP degraders suggested that a significant fraction of the ¹⁴CO₂ produced in long-term degradation assays may have originated from turnover of labelled microbial biomass rather than mineralization of [¹⁴C]PA or [¹⁴C]DEHP. It was estimated that a significant amount of DEHP with poor biodegradability and extractability remains in sludge-amended soil for extended periods of time despite the presence of microorganisms capable of degrading the compound (e.g., more than 40% of the DEHP added is not mineralized after 1 year).     

Formation and Degradation of Styrene Oxide Stereoisomers by Different Microorganisms

The formation of optically pure styrene oxides by oxidation of styrene and the isomerisation of styrene oxide to phenylacetaldehyde was investigated with different microorganisms.     

Bacterial Degradation of Diphenylmethane, a DDT Model Substrate

A strain of Hydrogenomonas was isolated by elective culture in a solution with diphenylmethane, an analogue of DDT, as the sole carbon source. Constitutive enzymes effected the oxidation and fission of one of the benzene rings of diphenylmethane, and phenylacetic acid was found as a major degradation product. Small amounts of phenylglyoxylic and benzoic acids were also generated from diphenylmethane by the bacterium. Phenylacetic acid, which contains the second benzene ring of diphenylmethane, was metabolized by inducible enzymes.     

Solubilization of Iron-Containing Minerals by Soil Microorganisms

Eighty-eight strains of microorganisms were isolated from soils collected in northern and southern Chile, and 10 fungi which showed the highest solubilizing action upon the iron in granodiorite were then selected. These fungi were incubated with the following iron-containing minerals: augite, hornblende, biotite, magnetite, hematite, and the igneous rock granodiorite. The solubility of iron in these minerals depended on their nature, crystalline structure, the concentration of metabolic products, or all three. Complex formation could be the mechanism involved, as a strong cation-exchange resin was not able to extract Fe from culture solutions. This conclusion is also confirmed by the R(F) values obtained by thin-layer chromatography of iron-containing culture solutions.     

Degradation of Organic Complexing Agents by Halophilic Microorganisms in Brines

The potential use of geologic salt beds as terminal repositories for nuclear waste has necessitated research on the interaction of the waste with indigenous microbiota. Microorganisms may affect actinide solubility by degrading organic complexing agents present in the waste. A halophilic bacterium and Archaea indigenous to a salt formation in New Mexico were examined for their ability to degrade acetate, oxalate, citrate, and ethylenediamine tetraacetate under aerobic conditions in low and high-magnesium brines. All complexing agents, except EDTA, were utilized, suggesting that microorganisms indigenous to such repositories can potentially play a beneficial role in mitigating actinide mobility.     

筛选微生物降解木质纤维素的研究进展

木质纤维素资源是自然界中含量丰富的可再生资源,利用微生物降解木质纤维素是一种重要的策略。在综合国内外对木质纤维素降解微生物的筛选方法和研究策略的基础上,从单一菌株、复合微生物菌系和组学技术三个方面对筛选微生物降解木质纤维素进行了总结和分析,阐述了各个策略的优势特点和应用价值,即单一菌株易于培养但降解能力较低,复合菌系降解能力强但传代稳定性较差,组学技术能够更好的解释微生物降解木质纤维素的机理,为筛选木质纤维素降解微生物提供一定的指导。同时提出使用合成生物学的策略进行相应微生物的筛选,旨在为筛选高效降解木质纤维素的微生物提供一定的参考。     

Adsorption of DDT and PCB by Nanomaterials from Residual Soil

This paper presents the findings of a study on adsorption of dichlorodiphenythreechloroethen (DDT) and polychlorinated biphenyls (PCBs) on three nanomaterials including Multi walled Carbon Nanotube (MWNT), nano-clay and nano-alumina. DDT and PCBs are of significant concern due their high toxicity and long environmental half-lives. Experiments were conducted using batch adsorption procedures at different DDT and PCBs concentrations, from 10 to 60 mg/L. The amounts of MWNT, nano-clay and Nano-alumina used were 0.25%, 0.50%, 0.75%, 1%, 2% and 10%. The adsorption of PCBs solution onto the MWNT, nano-clay and nano-alumina was characterized by an initial rapid adsorption which eventually became constant within 22, 20, and 17 hours, respectively. The adsorption of DDT solution onto the MWNT, nano-clay and nano-alumina was also characterized by an initial rapid adsorption which gradually became constant within 22, 22 and 16 hours, respectively. Results of this study indicated that MWNT was a better adsorbent material compared to nano-clay and nano-alumina for both contaminants in this study. While at 10% of MWNT 88.9% and 77% of DDT and PCB were removed by MWNT, respectively. The effect of pH and temperature were also investigated.     

Adsorption,Bioavailability, and Toxicity of Cadmium to Soil Microorganisms

The influence of adsorption on cadmium toxicity to soil microorganisms in soils was quantified as a function of solution and sorbent characteristics. The influence of adsorption on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. The sequence of relative percentage of FDA hydrolysis was reference smectite (RS) > untreated Vertisol (UV) > dithionate-citrate-bicarbonate (DCB)-treated Vertisol (DV) > H₂O₂-treated Vertisol (HV) in suspensions containing the same total Cd concentrations. The correlation between the percentage of FDA hydrolysis and activity of Cd²⁺ _(aq) illustrates that RS has a higher capacity of Cd adsorption. The microbial activity of RS was higher and the toxicity was lower than that of other soil samples. The HV had lower capacity of Cd adsorption so that its FDA hydrolysis was low and the Cd toxicity was high.