Source Of Energy For Growth Research Articles

Role of antioxidant phenolic compounds in plant responses to environmental stress

The betaproteobacterium Variovorax paradoxus strain TBEA6 is capable of using 3,3′-thiodipropionic acid (TDP) as sole carbon and energy source for growth. This thioether is employed for several industrial applications. It can be applied as precursor for the biotechnical production of polythioesters (PTE), which represent persistent bioplastics. Consequently, the genome of V. paradoxus strain TBEA6 was sequenced. The draft genome sequence comprises approximately 7.2 Mbp and 6852 predicted open reading frames. Furthermore, transposon mutagenesis to unravel the catabolism of TDP in strain TBEA6 was performed. Screening of 20,000 mutants mapped the insertions of Tn5::mob in 32 mutants, which all showed no growth with TDP as sole carbon source. Based on the annotated genome sequence together with transposon-induced mutagenesis, defined gene deletions, in silico analyses and comparative genomics, a comprehensive pathway for the catabolism of TDP is proposed: TDP is imported via the tripartite tricarboxcylate transport system and/or the TRAP-type dicarboxylate transport system. The initial cleavage of TDP into 3-hydroxypropionic acid (3HP) and 3-mercaptopropionic acid (3MP), which serves as precursor substrate for PTE synthesis, is most probably performed by the FAD-dependent oxidoreductase Fox. 3HP is presumably catabolized via malonate semialdehyde, whereas 3MP is oxygenated by the 3MP-dioxygenase Mdo yielding 3-sulfinopropionic acid (3SP). Afterwards, 3SP is linked to coenzyme A. The next step is the abstraction of sulfite by a desulfinase, and the resulting propionyl-CoA enters the central metabolism. Sulfite is oxidized to sulfate by the sulfite-oxidizing enzyme SoeABC and is subsequently excreted by the cells by the sulfate exporter Pse.

The genome of Variovorax paradoxus strain TBEA6 provides new understandings for the catabolism of 3,3′-thiodipropionic acid and hence the production of polythioesters

The betaproteobacterium Variovorax paradoxus strain TBEA6 is capable of using 3,3′-thiodipropionic acid (TDP) as sole carbon and energy source for growth. This thioether is employed for several industrial applications. It can be applied as precursor for the biotechnical production of polythioesters (PTE), which represent persistent bioplastics. Consequently, the genome of V. paradoxus strain TBEA6 was sequenced. The draft genome sequence comprises approximately 7.2Mbp and 6852 predicted open reading frames. Furthermore, transposon mutagenesis to unravel the catabolism of TDP in strain TBEA6 was performed. Screening of 20,000 mutants mapped the insertions of Tn5::mob in 32 mutants, which all showed no growth with TDP as sole carbon source. Based on the annotated genome sequence together with transposon-induced mutagenesis, defined gene deletions, in silico analyses and comparative genomics, a comprehensive pathway for the catabolism of TDP is proposed: TDP is imported via the tripartite tricarboxcylate transport system and/or the TRAP-type dicarboxylate transport system. The initial cleavage of TDP into 3-hydroxypropionic acid (3HP) and 3-mercaptopropionic acid (3MP), which serves as precursor substrate for PTE synthesis, is most probably performed by the FAD-dependent oxidoreductase Fox. 3HP is presumably catabolized via malonate semialdehyde, whereas 3MP is oxygenated by the 3MP-dioxygenase Mdo yielding 3-sulfinopropionic acid (3SP). Afterwards, 3SP is linked to coenzyme A. The next step is the abstraction of sulfite by a desulfinase, and the resulting propionyl-CoA enters the central metabolism. Sulfite is oxidized to sulfate by the sulfite-oxidizing enzyme SoeABC and is subsequently excreted by the cells by the sulfate exporter Pse.

The eurythermal adaptivity and temperature tolerance of a newly isolated psychrotolerant Arctic Chlorella sp.

A new strain of Chlorella sp. (Chlorella-Arc), isolated from Arctic glacier melt water, was found to have high specific growth rates (μ) between 3 and 27 °C, with a maximum specific growth rate of 0.85 day−1 at 15 °C, indicating that this strain was a eurythermal strain with a broad temperature tolerance range. To understand its acclimation strategies to low and high temperatures, the physiological and biochemical responses of the Chlorella-Arc to temperature were studied and compared with those of a temperate Chlorella pyrenoidosa strain (Chlorella-Temp). As indicated by declining F v/F m, photoinhibition occurred in Chlorella-Arc at low temperature. However, Chlorella-Arc reduced the size of the light-harvesting complex (LHC) to alleviate photoinhibition, as indicated by an increasing Chl a/b ratio with decreasing temperatures. Interestingly, Chlorella-Arc tended to secrete soluble sugar into the culture medium with increasing temperature, while its intracellular soluble sugar content did not vary with temperature changes, indicating that the algal cells might suffer from osmotic stress at high temperature, which could be adjusted by excretion of soluble sugar. Chlorella-Arc accumulated protein and lipids under lower temperatures (<15 °C), and its metabolism switched to synthesis of soluble sugar as temperatures rose. This reflects a flexible ability of Chlorella-Arc to regulate carbon and energy distribution when exposed to wide temperature shifts. More saturated fatty acids (SFA) in Chlorella-Arc than Chlorella-Temp also might serve as the energy source for growth in the cold and contribute to its cold tolerance.

A jack-of-all-trades: 2-mercaptosuccinic acid.

2-Mercaptosuccinic acid (MS) is an important and versatile substance for diverse fields of applications of which the most significant are surveyed in this article. Biological, chemical, and physical properties of MS as well as the knowledge of its synthesis and microbial degradation are illustrated. In addition, exemplary structural analogs of the organic sulfur compound are commented. The key application of MS in nanotechnology is discussed in detail with particular emphasis on quantum dots (nanocrystals) and self-assembled monolayers in combination with gold or silver. Furthermore, some medical and pharmaceutical applications are given, inter alia in bioimaging, as a nanocarrier, and with regard to the antimicrobial activity of MS-silver and MS-gold nanoparticles. Moreover, biological and chemical applications of MS are exemplified: the thiol compound can serve as an inhibitor for glutathione peroxidase, or the toxicity of substances can be increased due to the presence of MS in the respective cells or tissues. In the field of cosmetics, MS is widely utilized as a reducing agent for numerous products as explained in this article. Additionally, the microbial utilization of MS as a carbon and energy source for growth is elucidated in-depth, providing insight into different catabolic mechanisms.

Aerobic transformation of BDE-47 by a Pseudomonas putida sp. strain TZ-1 isolated from PBDEs-contaminated sediment.

A bacterial isolate, TZ-1, was isolated from contaminated sediment near electronic waste dismantling workshops, Taizhou, China that degraded 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47). The isolate was identified as Pseudomonas putida sp. with respect to its morphology, biochemical characteristics and 16SrDNA sequence analysis. TZ-1 can use BDE-47 as the sole carbon and energy source for growth in mineral salt medium. The isolate degraded BDE-47 up to 49.96 % of the initially applied concentration of 50 μg L(-1) after 7 days of incubation at 150 rpm, 30°C. Static conditions with pH 6.5 and temperature 30°C were considered to be optimum for BDE-47 biodegradation. Addition of co-substrates promoted cell growth, but decreased the degradation rate for BDE-47.

3-Ketosteroid 9α-hydroxylase enzymes: Rieske non-heme monooxygenases essential for bacterial steroid degradation.

Various micro-organisms are able to use sterols/steroids as carbon- and energy sources for growth. 3-Ketosteroid 9α-hydroxylase (KSH), a two component Rieske non-heme monooxygenase comprised of the oxygenase KshA and the reductase KshB, is a key-enzyme in bacterial steroid degradation. It initiates opening of the steroid polycyclic ring structure. The enzyme has industrial relevance in the synthesis of pharmaceutical steroids. Deletion of KSH activity in sterol degrading bacteria results in blockage of steroid ring opening and is used to produce valuable C19-steroids such as 4-androstene-3,17-dione and 1,4-androstadiene-3,17-dione. Interestingly, KSH activity is essential for the pathogenicity of Mycobacterium tuberculosis. Detailed information about KSH thus is of medical relevance, and KSH inhibitory compounds may find application in combatting tuberculosis. In recent years, the 3D structure of the KshA protein of M. tuberculosis H37Rv has been elucidated and various studies report biochemical characteristics and possible physiological roles of KSH. The current knowledge is reviewed here and forms a solid basis for further studies on this highly interesting enzyme. Future work may result in the construction of KSH mutants capable of production of specific bioactive steroids. Furthermore, KSH provides an promising target for drugs against the pathogenic agent M. tuberculosis.

Real-time PCR for quantification in soil of glycoside hydrolase family 6 cellulase genes.

Cellulose is the main structural component of the cell walls of higher plants, representing c. 35-50% of a plant's dry weight; after decomposition and transformation, and constituting a large part of soil organic matter. Telluric micro-organisms able to use cellulose as carbon and energy sources for growth are widely distributed in the environment, but the factors controlling the rate of cellulose degradation are not well understood. In this study, we have developed a quantitative real-time PCR (qPCR) primer set to quantify the glycoside hydrolase family 6 (GH6 family) cellulase genes in soil samples. The qPCR assays were linear over 8 orders of magnitude and sensitive down to 10 copies per assay. qPCR analysis of contrasted soil samples showed densities between 2·47×10(7) and 1·48×10(10) copies per gram of soil. Cloning and sequencing of the PCR products from environmental DNA confirmed both specific amplification (more than 96%) and the wide diversity targeted by the primer set, throughout nearly all the GH6 family, including sequences of bacteria and fungi. Telluric micro-organisms able to use cellulose as carbon and energy sources for growth are widely distributed in the environment, but the factors controlling the rate of cellulose degradation are not well understood. The objective of our study was to develop a qPCR for rapid quantification of GH6 cellulase genes in soil. This qPCR could be applied to study the potential for cellulose degradation in different soils in order to better understand the factors controlling the stability of the soil organic matter.

Trehalose-6-phosphate and SnRK1 kinases in plant development and signaling: the emerging picture.

Carbohydrates, or sugars, regulate various aspects of plant growth through modulation of cell division and expansion. Besides playing essential roles as sources of energy for growth and as structural components of cells, carbohydrates also regulate the timing of expression of developmental programs. The disaccharide trehalose is used as an energy source, as a storage and transport molecule for glucose, and as a stress-responsive compound important for cellular protection during stress in all kingdoms. Trehalose, however, is found in very low amounts in most plants, pointing to a signaling over metabolic role for this non-reducing disaccharide. In the last decade, trehalose-6-phosphate (T6P), an intermediate in trehalose metabolism, has been shown to regulate embryonic and vegetative development, flowering time, meristem determinacy, and cell fate specification in plants. T6P acts as a global regulator of metabolism and transcription promoting plant growth and triggering developmental phase transitions in response to sugar availability. Among the T6P targets are members of the Sucrose-non-fermenting1-related kinase1 (SnRK1) family, which are sensors of energy availability and inhibit plant growth and development during metabolic stress to maintain energy homeostasis. In this review, we will discuss the opposite roles of the sugar metabolite T6P and the SnRK1 kinases in the regulation of developmental phase transitions in response to carbohydrate levels. We will focus on how these two global regulators of metabolic processes integrate environmental cues and interact with hormonal signaling pathways to modulate plant development.

Macronutrient selection, absorption and energy budget of juveniles of the Australasian sea cucumber,Australostichopus mollis, feeding on mussel biodeposits at different temperatures

This study was set up to examine the selection and absorption of macronutrients (lipid, protein and carbohydrate) of juveniles of the Australasian sea cucumber Australostichopus mollis, feeding on an effective natural feed (mussel waste) at different temperatures. Our results indicate that the juveniles select and absorb lipid more efficiently than carbohydrate and protein at all temperatures. However, the overall magnitude of absorption of carbohydrate and protein make them the main source of nutritional energy for juvenile sea cucumbers. Seawater temperature affects the feeding behaviour of the juveniles, reducing the selection efficiency of macronutrients, while increasing metabolic energy demand, resulting in less energy available for growth. These results show the importance of each macronutrient in the diet of A. mollis as a source of energy for growth, which opens up the possibility to replace more expensive nutrient sources, such as protein and lipid, with less costly carbohydrate to reduce costs of diet formulation.

Biodegradation and kinetic analysis of phthalates by an Arthrobacter strain isolated from constructed wetland soil

A bacterial strain C21 isolated from constructed wetland soil was identified as Arthrobacter sp. based on 16S rRNA gene sequence analysis and physio-biochemical characteristics and was capable of utilizing di-n-butyl phthalate (DBP) as a carbon and energy source for growth. Strain C21 can also utilize other phthalates (PAEs) up to a molecular weight of 390.56 and phthalic acid (PA). The biodegradability of these compounds decreased with the increase in the length of phthalate alkyl chains and molecular weight. Kinetic analysis indicated that the strain C21 cell growth on DBP fitted well with Haldane-Andrews' model (R (2) > 0.98) with μ max, K s, and K i of 0.12/h, 4.2 mg/L, and 204.6 mg/L, respectively. When the initial DBP concentration was lower than 100 mg/L, DBP biodegradation reaction fitted with the first-order kinetics. The results suggested that Arthrobacter strain C21 played an active role in the bioremediation of the wetland contaminated with phthalates.

Architecture and functions of a multipartite genome of the methylotrophic bacterium Paracoccus aminophilus JCM 7686, containing primary and secondary chromids

BackgroundParacoccus aminophilus JCM 7686 is a methylotrophic α-Proteobacterium capable of utilizing reduced one-carbon compounds as sole carbon and energy source for growth, including toxic N,N-dimethylformamide, formamide, methanol, and methylamines, which are widely used in the industry. P. aminophilus JCM 7686, as many other Paracoccus spp., possesses a genome representing a multipartite structure, in which the genomic information is split between various replicons, including chromids, essential plasmid-like replicons, with properties of both chromosomes and plasmids. In this study, whole-genome sequencing and functional genomics approaches were applied to investigate P. aminophilus genome information.ResultsThe P. aminophilus JCM 7686 genome has a multipartite structure, composed of a single circular chromosome and eight additional replicons ranging in size between 5.6 and 438.1 kb. Functional analyses revealed that two of the replicons, pAMI5 and pAMI6, are essential for host viability, therefore they should be considered as chromids. Both replicons carry housekeeping genes, e.g. responsible for de novo NAD biosynthesis and ammonium transport. Other mobile genetic elements have also been identified, including 20 insertion sequences, 4 transposons and 10 prophage regions, one of which represents a novel, functional serine recombinase-encoding bacteriophage, ϕPam-6. Moreover, in silico analyses allowed us to predict the transcription regulatory network of the JCM 7686 strain, as well as components of the stress response, recombination, repair and methylation machineries. Finally, comparative genomic analyses revealed that P. aminophilus JCM 7686 has a relatively distant relationship to other representatives of the genus Paracoccus.ConclusionsP. aminophilus genome exploration provided insights into the overall structure and functions of the genome, with a special focus on the chromids. Based on the obtained results we propose the classification of bacterial chromids into two types: “primary” chromids, which are indispensable for host viability and “secondary” chromids, which are essential, but only under some environmental conditions and which were probably formed quite recently in the course of evolution. Detailed genome investigation and its functional analysis, makes P. aminophilus JCM 7686 a suitable reference strain for the genus Paracoccus. Moreover, this study has increased knowledge on overall genome structure and composition of members within the class Alphaproteobacteria.

Production of polyhydroxyalkanoates by Ralstonia eutropha from volatile fatty acids

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible thermoplastics that can be synthesized in various microorganisms. Volatile fatty acids (VFAs) are produced by anaerobic treatment of organic wastes that can be utilized as inexpensive substrates for PHA synthesis. In this study, several Ralstonia eutropha strains were grown on the mixture of VFAs (acetic, propionic, and butyric acid) as its carbon and energy source for growth and PHA synthesis. R. eutropha KCTC 2658 accumulated PHAs up to 50% of dry cell weight from total 5 g/L of mixed VFAs (acetic acid: propionic acid: butyric acid=1: 2: 2). In batch culture of R. eutropha KCTC2658 in a 5 L fermentor, a homopolymer of poly(3-hydroxybutyrate) [P(3HB)] was produced from 20 g/L glucose as a sole carbon source with dry cell weight of 8.4 g/L and PHA content of 30%. In fed-batch culture, two feeding strategies, pulse or pH-stat, were applied to add VFAs to the fermentor. When VFAs were fed using pH-stat feeding strategy after 40 h, a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was produced with dry cell weight of 8.1 g/L, PHA content of 50%, and 3HV fraction of 20 mol%.

Biodegradation of acephate and methamidophos by a soil bacterium Pseudomonas aeruginosa strain Is-6

The aim of this study was to isolate and characterize a new acephate-degrading bacteria from agricultural soil and to investigate its biodegradation ability and pathway of degradation. A bacterial strain Is-6, isolated from agriculture soil could completely degrade and utilize acephate as the sole carbon, phosphorus and energy sources for growth in M9 medium. Analysis of the 16S rRNA gene sequence and phenotypic analysis suggested that the strain Is-6 was belonging to the genus Pseudomonas aeruginosa. Strain Is-6 could completely degrade acephate (50 mg L−1) and its metabolites within 96 h were identified by high-performance liquid chromatography (HPLC) and electron spray ionization-mass spectrometry (ESI-MS) analyses. When exposed to the higher concentration, the strain Is-6 showed 92% degradation of acephate (1000 mg L−1) within 7 days of incubation. It could also utilize dimethoate, parathion, methyl parathion, chlorpyrifos and malathion. The inoculation of strain Is-6 (107 cells g−1) to acephate (50 mg Kg−1)-treated soil resulted in higher degradation rate than in noninoculated soils. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the environment.

Biodegradation of decabromodiphenyl ether (BDE-209) by a metal resistant strain, Bacillus cereus JP12

A metal resistant bacterial strain, Bacillus cereus JP12, could use decabromodiphenyl ether (BDE-209) as the sole carbon and energy source for growth in mineral salt medium. Under the conditions of pH 6.0, 30°C, 150 rpm and an inoculum of OD600=0.6, more than 88% of the initial BDE-209 (1mg/L) was degraded after 12 days. The addition of appropriate surfactants and additional carbon sources could enhance the biodegradation efficiency of BDE-209. The presence of Cu(2+) (≤ 8 mg/L) and Zn(2+) (≤ 15 mg/L) provided a slight stimulating effect on BDE-209 removal. However, BDE-209 biodegradation efficiency was decreased when adding higher levels of metals due to reduced substrate availability caused by excess metal adsorption into the cell surface. Biosorption of heavy metals by JP12 led to release of light metals such as K(+) and Na(+). A BDE-209 biodegradation pathway was proposed on the basis of metabolite identification.

Enhancement of growth and intestinal flora in grass carp: The effect of exogenous cellulase

Plant protein sources have been identified to have the greatest potential to replace fish meal protein in aquafeeds. However, plant ingredients contain significant quantities of carbohydrates, and the ability of fish to utilize dietary carbohydrates as energy sources for growth is limited. Included in the carbohydrate group, cellulose is not tolerated by most fish. In the present study, the grass carp, a typical herbivorous fish, fed with duckweed was selected to study the effect of exogenous cellulase on the growth. The results of 2-month feeding experiment showed that the cellulase promoted the growth of grass carp. In addition, the cellulase increased various digestive enzyme activities, such as cellulase, amylase and protease but not the lipase activity. Meanwhile, the polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analysis indicated that the intestinal microbiota of fish fed with the supplemental cellulase changed in bacteria species and density. Band patterns derived from control and cellulase samples showed a low degree of similarity when analyzed by cluster analysis. Some bands were unique to control samples, whereas other bands were obtained only with samples of the cellulase group. The 16S rRNA gene sequencing identified that Proteobacteria and Firmicutes were the two dominant groups, and the emergence of certain bacterial strains including Bacilli and Sphingomonas may contribute to the digestion of cellulose. The former researches and this paper results suggest that the endogenous cellulase is far from sufficient to fully digest the ingested fiber, so cellulase should be developed as a kind of aquatic additive.

Gene Cloning and Function Analysis Involved in the Biodegradation of Aromatic Compounds by Bacillus NAPZ

A bacterial strain NAPZ, which utilized polycyclic aromatic hydrocarbons (PAHs) as the sole carbon and energy source for growth, was studied on its apparent characteristics, key gene structure and functions. It was preliminarily identified as a Bacillus sp. according to its physiological characteristics and the phylogenetic property of its 16S rRNA gene sequence. Based on the reported RHD gene sequences, a pair of primers was designed to amplify the RHD gene from the genomic DNA of strain NAPZ by PCR. Then, the RHD gene was cloned and sequenced. Based on this sequence and its related sequences in the GenBank database, a multiple alignment was conducted then a phylogenetic tree was constructed with DNAMAN and MEGA software. The analysis revealed that strain NAPZ oxidized PAHs via ring hydroxylating dioxygenase (RHD) pathway. The study provided experimental and theoretical support for revealing the structure and function of key genes as well as the PAHs-degrading pathways in strain NAPZ.

Isolation and characterization of a novel 2-methyl-4-chlorophenoxyacetic acid-degrading Enterobacter sp. strain SE08

A bacterial strain (SE08) capable of utilizing 2-methyl-4-chlorophenoxy acetic acid (MCPA) as the sole carbon and energy source for growth was isolated by continuous enrichment culturing in minimal salt medium (MSM) from a long term MCPA exposed soil. This bacterial strain was identified as Enterobacter sp. based on morphological, physiological and biochemical tests, as well as 16S rRNA sequence analysis. Its ability to degrade MCPA was determined using high performance liquid chromatography. The strain SE08 can tolerate unusually high MCPA concentrations (125–2000mg/L). The influences of culturing factors (initial concentration, pH, and temperature) on the bacterial growth and substrate degradation were studied. The results showed that the optimal MCPA degradation occurred at an MCPA concentration of 500mg/L, 30°C and pH 6.0. Under these conditions, 68.5 percent of MCPA in MSM was degraded by SE08, and the OD600nm reached 0.64 after culturing for 72h. The degradation of MCPA could be enhanced by addition of both carbon and nitrogen sources. At an initial MCPA concentration of 500mg/L, when 5g/L glucose and 2.5g/L yeast extract were added into the MSM media, the MCPA degradation was significantly increased to 83.8 percent, and OD600nm was increased to 1.09 after incubation at 30°C and pH 6.0 for 72h. This is the first study showing that an Enterobacter sp. strain is capable of degrading MCPA, which might provide a new approach for the remediation of MCPA contaminated soil and contribute to the limited knowledge about the function of Enterobacter species.

Isolation, identification and growth determination of lactic acid-utilizing yeasts from the ruminal fluid of dairy cattle

Ruminal organic acid production, especially lactic acid, can be modified by feeding cattle highly concentrated diets, which have been shown to adversely affect dairy cattle health. Therefore, the use of lactic acid-utilizing organisms is considered to be a potential method for controlling lactic acid levels. This study was conducted to isolate and identify lactic acid-utilizing yeasts from the ruminal fluid of dairy cattle and to determine the specific growth rate and generation time when using lactic acid as a carbon source instead of glucose. Seventeen yeast isolates were examined in this study. Yeasts isolated from dairy cattle that were fed a high cassava pulp diet (HCP) had higher specific growth rates and shorter generation times than yeasts isolated from dairy cattle that were fed a high-concentrate diet (HC) and a mixed diet (M). The three most effective yeasts in terms of specific growth rate and generation time were Pichia kudriavzevii, Candida rugosa and Kodamaea ohmeri, with 99, 100 and 99% nucleotide identities, respectively. These three isolates could be used as potential probiotics in dairy cattle diets. This study demonstrates that yeasts isolated from the ruminal fluid of dairy cattle can utilize lactic acid as a carbon and energy source for growth. The isolated yeasts can be used as probiotic supplements for dairy cattle that are fed highly concentrated diets to reduce ruminal lactic acid production.

Biodegradation of the neonicotinoid insecticide Acetamiprid by bacterium Pigmentiphaga sp. strain AAP-1 isolated from soil

The Acetamiprid-degrading bacterium AAP-1 was isolated from contaminated soil, and identified as Pigmentiphaga sp. combined traditionary categorization method with modern molecule method. The strain could utilize Acetamiprid as the sole carbon, nitrogen and energy source for growth and metabolized 100 mgL(-1) Acetamiprid within 2.5h. During the degradation of Acetamiprid, one N-deacetylation metabolite, was characterized by FT-IR, GC-MS and NMR analysis. A novel microbial biodegradation pathway for Acetamiprid was proposed on the basis of the metabolite. Compared with uninoculated soils, the addition of the AAP-1 strain into soils treated with Acetamiprid gained a higher degradation rate, and the bacteria community analysis by T-RFLP in contaminated soil recovered after inoculation of the AAP-1 strain. On the basis of these results, strain AAP-1 has the potential to be used in the bioremediation of Acetamiprid-contaminated environments. This is the first report of Acetamiprid-degrading isolate from the genus of Pigmentiphaga.

Isolation and characterization of Acidithiobacillus ferrooxidans strain QXS-1 capable of unusual ferrous iron and sulfur utilization

A novel Acidithiobacillus ferrooxidans strain QXS-1 was isolated from the acid mine drainage of Qixiashan Pb–Zn–Ag mine area in China. The isolate QXS-1 is a motile, rod-shaped Gram-negative bacterium with an optimum growth at 30°C and pH 2.0. The phylogenetic analysis has demonstrated that QXS-1 is a new strain of A. ferrooxidans. The strain QXS-1 exhibited an unusual trait on the utilization of ferrous iron and sulfur as energy sources. The sulfur-domesticated QXS-1 cells only utilized sulfur as energy source for growth when both ferrous iron and sulfur are available, whereas ferrous-domesticated QXS-1 cells prefer to simultaneously utilize both ferrous iron and sulfur as energy source for growth in the presence of both substrates. The QXS-1 cells accumulated intracellular hydrophilic sulfur during growth. Based on the ultrastructure study, we deduced that the accumulated sulfur in QXS-1 exists in both octasulfur ring form and polysulfide form. The strain QXS-1 exhibited remarkable marmatite-bioleaching capacity. It is able to extract 6585mg/L zinc from marmatite within 18days in shake flask.