Physio-biochemical Characteristics Research Articles

Isolation and characterization of a novel cinosulfuron degrading Kurthia sp. from a methanogenic microbial consortium

A novel bacterial strain LAM0713 was isolated from a methanogenic bacterial complexes and identified as Kurthia sp. based on morphological, cultural, physio-biochemical characteristics and analysis of 16S rDNA sequence. Strain LAM0713 was found to be capable of utilizing cinosulfuron as sole nitrogen source for growth over a wide range of temperature (20-40 °C) and pH (5.0-9.0). Response surface methodology was used to optimize the degradation conditions. Strain LAM0713 could efficiently degrade 92.4% of initially supplemented 50 mg·L(1) cinosulfuron under the optimum conditions (pH 6.9, 31.8 °C) within 5 days. Five intermediates formed during cinosulfuron degradation were detected by liquid chromatography mass spectrometry (LC-MS), and a metabolic pathway for cinosulfuron degradation was proposed via cleavage of the sulfonylurea bridge. It is the first report showing that Kurthia sp. strain could degrade sulfonylurea herbicides, suggesting that strain LAM0713 may provide new insight into microbial degradation of herbicides.

Yeast community associated with the solid state fermentation of traditional Chinese Maotai-flavor liquor

Yeasts are the most important group of microorganisms contributing to liquor quality in the solid-state fermentation process of Chinese Maotai-flavor liquor. There occurred a complex yeast community structure during this process, including stages of Daqu (the starter) making, stacking fermentation on the ground and liquor fermentation in the pits. In the Daqu making stage, few yeast strains accumulated. However, the stacking fermentation stage accumulated nine yeast species with different physio-biochemical characteristics. But only four species kept dominant until liquor fermentation, which were Zygosaccharomyces bailii, Saccharomyces cerevisiae, Pichia membranifaciens, and Schizosaccharomyces pombe, implying their important functions in liquor making. The four species tended to inhabit in different locations of the stack and pits during stacking and liquor fermentation, due to the condition heterogeneity of the solid-state fermentation, including the different fermentation temperature profiles and oxygen density in different locations. Moreover, yeast population was much larger in the upper layer than that in the middle and bottom layers in liquor fermentation, which was in accordance with the profile of reducing sugar consumption and ethanol production. This was a systematical investigation of yeast community structure dynamics in the Maotai-flavor liquor fermentation process. It would be of help to understand the fermentative mechanism in solid-state fermentation for Maotai-flavor liquor.

English

Salinity is one of the main environmental constraints to crop productivity worldwide.  The aim of the experiment was to study the role of mycorrhiza (Glomus clarum Nicol. & Schenck) in tolerance of wheat genotypes to salt stress in terms of growth, physiological and biochemical parameters. Wheat genotypes (cvs. Henta, Moaya and Samma) were grown at three levels of NaCl (0.75, 1.5 and 3 g kg-1 soil) with or without mycorrhiza. The growth and physio-biochemical characteristics of all genotypes decreased with increasing levels of salinity except concentration of reducing sugars, sodium and proline, and at 3 g of NaCl, only genotype ‘Samma’ survived and showed resistant against severe salinity. However, inoculation of mycorrhiza enhanced the growth and accumulation of nutrients, reducing sugars, total soluble carbohydrates, Chlorophyll (Chl) a and Chl b, carotene, proline and protein by reducing Na. The present study suggested that inoculation of fungi was effective in improving the tolerance of wheat genotypes by improving the accumulation of nutrients and soluble solutes that might be responsible for osmotic adjustment of plant to counteract oxidative damage generated by salinity.   Key words: Mycorrhiza, nutrients, osmolytes, salinity, Triticum aestivum, pigments, protein.

Isolation, identification and degradation characteristics of a MCPA-degrading bacterial strain

A bacterial strain named SE08 capable of degrading 2–methyl–4–chlorophenoxy acetic acid(MCPA) was newly isolated by enrichment culture from the tobacco field soil in Chenzhou district,Hunan province.Strain SE08 was temporarily identified as Enterobacter sp.based on morphological and physio-biochemical characteristics combined with 16S rDNA sequence analysis.Strain SE08 could effectively degrade MCPA in concentration range 150–1 000 mg/L.And 45.21% of MCPA(500 mg/L) could be degraded by strain SE08 in 24 h.The optimal pH value and temperature for MCPA degradation by SE08 was 6.0 and 30 °C,respectively.

Screening of the Bacterium for Chlorobenzene Degradation and its Enzymatic Properties

A dominant bacterium (LW13) for the degradation of chlorobenzene was selected from maturity sludge in a novel combined bio-filter polluted by chlorobenzene gas. Based on the morphological characteristics observation, physio-biochemical characteristics and 16S rDNA sequence homology analysis, strain LW13 was identified as Lysinibacillus fusiformis. Crude enzyme from the fermentation was extracted and their enzymatic properties were also investigated. Results showed that the degradation enzyme produced by the bacteria belong to extracellular enzymes. The purity of the enzyme was determined by SDS-PAGE gel electrophoresis and the molecular weight was found to be 52 kDa. The optimum pH value was about 8.0 with the optimum temperature of 45° C. Throughout the purification process, 85-fold of enzyme purification was achieved with the recovery of 20.69%.

Leaf Functional Traits and Stem Wood Characteristics Influencing Biomass Productivity of Mulberry (Morus spp. L) Genotypes Grown in Short-Rotation Coppice System

The present study was undertaken to obtain insights into the productivity determinant traits of mulberry (Morus spp. L.), a potential bioenergy tree crop. Our objectives were to identify leaf functional traits and stem wood characteristics that are correlated to biomass yield of mulberry. Based on the growth performance, six mulberry genotypes from different performance groups including high (Selection1 and Thaibeelad), average (Mysore Local) and poor (Triploid10, Jhoropakari and Selection1635) were selected for the study, along with a reference high-yielding genotype (Victory1). The study was conducted in Southern India for two consecutive years, covering two experimental seasons including exp season I (July 2009 to October 2009) and exp season II (July 2010 to October 2010). Mulberry trees were cultivated in a short-rotation coppice system under well-irrigated optimum farming conditions. Data were collected on biomass yield along with several leaf-level physiobiochemical characteristics and wood quality parameters. Significant genetic variation was recorded amongst the genotypes in most of the studied parameters. Fifteen out of a total of 22 traits, used in computing correlation coefficient matrix, were found to correlate with aboveground biomass yield. Light-saturated rate of photosynthesis, performance index, leaf nitrogen content, minimum leaf water potential and leaf-specific hydraulic conductance showed strong positive correlation with biomass productivity. Wood density, wood cross-sectional area and fibre cell density exhibited tight correlation with woody biomass yield. In conclusion, the identified 15 characteristics could be useful in the selection of suitable mulberry genotypes for higher biomass yield.

Performance of Denitrifying Phosphorous Removal Process Employing Nitrite as Electron Acceptor and the Characterization of Dominant Functional Populations

A sequencing batch reactors (SBR) was adopted to investigate the denitrifying phosphorus removal efficiency employing nitrite as electron acceptor under anaerobic/anoxic condition. The experimental results showed that high nitrogen and phosphorus removal efficiency could be obtained under the following conditions: nitrite concentration of 30~40 mg/L, COD concentration of 400 mg/L, pH 8.0±0.2 in anaerobic stage and pH 7.2±0.2 in anoxic stage, sludge retention time (SRT) of 22 days. When the reactor performed steadily, a dominant functional strain was screened from the activated sludge, which has high nitrite and phosphorus removal efficiency. Batch tests results showed that the removal degree of nitrite and phosphorus could reach 99.18% and 84.94% respectively when their concentrations were 20mg/L and 10mg/L. according to the morphology and physio-biochemical characteristics, and the results of 16S rDNA sequencing, it is determined that the strain belongs to the Genus of Sphingobacterium. The experimental results achieved in this study might offer guidance to the development of shortcut denitrifying phosphorus removal process.

Performance of Denitrifying Phosphorous Removal Process Employing Nitrite as Electron Acceptor and the Characterization of Dominant Functional Populations

A sequencing batch reactors (SBR) was adopted to investigate the denitrifying phosphorus removal efficiency employing nitrite as electron acceptor under anaerobic/anoxic condition. The experimental results showed that high nitrogen and phosphorus removal efficiency could be obtained under the following conditions: nitrite concentration of 30~40 mg/L, COD concentration of 400 mg/L, pH 8.0±0.2 in anaerobic stage and pH 7.2±0.2 in anoxic stage, sludge retention time (SRT) of 22 days. When the reactor performed steadily, a dominant functional strain was screened from the activated sludge, which has high nitrite and phosphorus removal efficiency. Batch tests results showed that the removal degree of nitrite and phosphorus could reach 99.18% and 84.94% respectively when their concentrations were 20mg/L and 10mg/L. according to the morphology and physio-biochemical characteristics, and the results of 16S rDNA sequencing, it is determined that the strain belongs to the Genus of Sphingobacterium. The experimental results achieved in this study might offer guidance to the development of shortcut denitrifying phosphorus removal process.

Isolation, Identification and Phylogenetic Analysis of an Alkalophilic Methanosarcina

An alkalophilic methanogen T13 was isolated by anaerobic techniques of Hungate from cow muck in Hongyuan county,Sichuan,China enriched in culture for methanogen at 15 ℃.Its optimum pH for producing methane was 8.5,and the temperature for growth was observed at the range of 8~45 ℃.The culture was visible particulate.Cells were aggregated and gram-positive.The colony was pale yellow,mulberry-like and fluoresced.T13 could grow using acetate,methanol or methylamine as sole carbon source,and it was sensitive to chloramphenicol and gentamicin.The optimum temperature and NaCl concentration for its growth were 30 ℃ and 0~0.15 mol L-1,respectively.It grew at the pH range between 6.5 and 9.5.The morphological and physio-biochemical characteristics combined with 16S rDNA sequence analysis of strain T13 demonstrated that it was a strain of Methanosarcina mazei.Since its optimum pH for growth was 8.5,strain T13 therefore was considered preliminarily as a new strain of M.mazei.

Isolation and characterization of Rhodococcus sp.BX2 capable of degrading bensulfuron-methyl

Bensulfuron-methyl (BSM) is a widely applicable sulfonylurea herbicides. However, BSM remains in environment for extended period of time (over 100 days) and causes a series of environmental problems. In this study, BX2, a strain presents high BSM degradation abilities, was isolated from an activated sludge sample using a continuous enrichment method and determined to be a member of the genus Rhodococcus based on its physiobiochemical characteristics and 16S rRNA gene sequence. Strain BX2 degradated 92% BSM from an initial concentration of 20 mg/L within a 7- day incubation at 35℃. The specific degradation rate increased with an increase in the initial BSM concentration and the maximum specific degradation rate obtained was 0.146 mg/(mg·d) at 140 mg/L. BSM degradation by strain BX2 can be presented by Haldane’s inhibition equation and the kinetic parameters were: = 16.75 mg/(mg·d), = 7809.36 mg/L and = 2.41 mg/L, respectively. These results indicated that the strain BX2 could be an excellent candidate for bioremediation of BSM-contaminated environments due to its high BSM-degradative ability. Key words: Bensulfuron-methyl (BMS), Rhodococcus sp.BX2, isolation, biodegradation.

Humic analog AQDS and AQS as an electron mediator can enhance chromate reduction by Bacillus sp. strain 3C3

Humus as an electron mediator is recognized as an effective strategy to improve the biological transformation and degradation of toxic substances, yet the action of humus in microbial detoxification of chromate is still unknown. In this study, a humus-reducing strain 3C(3) was isolated from mangrove sediment. Based on the analyses of morphology, physiobiochemical characteristics, and 16S rRNA gene sequence, this strain was identified Bacillus sp. Strain 3C(3) can effectively reduce humic analog anthraquinone-2,6-disulfonate (AQDS) and anthraquinone-2-sulfonate (AQS) with lactate, formate, or glucose as electron donors. When the cells were killed by incubation at 95°C for 30 min or an electron donor was absent, the humic reduction did not occur, showing that the humic reduction was a biochemical process. However, strain 3C(3) had low capability of chromate reduction under anaerobic conditions, despite of having strong tolerance of the toxic metal. But in the presence of humic substances AQDS or AQS, we found that chromate reduction by strain 3C(3) was enhanced greatly. Because strain 3C(3) is an effective humus-reducing bacterium, it is proposed that humic substances could serve as electron mediator to interact with chromate and accelerate chromate reduction. Our results suggest that chromate contaminations can be detoxified by adding humic analog (low to 0.1 mM) as an electron mediator in the microbial incubation.

Physiological and Biochemical Characteristics and Desilication Ability of Bacillus Mucilaginosus Screened from Poyang Lake Area of Jiangxi Province

18 strains of Bacillus mucilaginosus were sampled from Poyang Lake area of Jiangxi province in China . Morphology and physio-biochemical characteristics and desilication ability on bauxite were studied. The results showed that all strains are rods and produced spores from elliptical to circular， while strains of P8、P11、P15 are short rod. Gram reaction of 18 strains are negative.The strains can use nitrites and ammonium salt as nitrogen source, and survived in the nitrogen free medium. P4、P3 showed strong desilication ability, compared to blank control the content of soluble SiO2 increased to 4.57、4.13 times respectively; P2、 P7、P9 could tolerate 4% NaCl and were growing well at the temperature ranging from 25~35 °C.

A strain of Streptomyces griseoruber isolated from rhizospheric soil of Chinese cabbage as antagonist to Plasmodiophora brassicae

To find potential biocontrol agents for Plasmodiophora brassicae, a total of 63 actinobacteria were isolated from the rhizospheric soil of Chinese cabbage that were collected from Sichuan province in China. Isolates were screened by measuring the resting spores' germination inhibition. The suppressive effects of six antagonistic strains against clubroot on Chinese cabbage in the glasshouse and the field were assessed, respectively. Strain A316 was the most promising antagonist against clubroot, which showed the highest control values of 73.69% in the glasshouse experiment and 65.91% in the field trial. Based on the 16S rDNA sequence analysis, strain A316 was most closely related to Streptomyces griseoruber NBRC 12873 (99.9% similarity). Together with morphological, cultural and physio-biochemical characteristics, strain A316 was identified as Streptomyces griseoruber. The results indicate that the isolate A316 might have the potential possibility to be used as an antagonist against P. brassicae. This is the first report of S. griseoruber for controlling clubroot.

Isolation, Identification and Degradation Characterization of a p-Chloroaniline Degrading Strain

A bacterium (strain ycsd02) was isolated from rhizosphere soil in phragmites wetland using the enrichment culture contaminated with p-Chloroaniline (p-CA). Morphology, physio-biochemical characteristics and phylogenetic analysis based on 16S rDNA sequence indicated that the shape of the single cell is pole, which clearly belongs to Bacillus licheniformis. The optimal conditions for satisfactory degradation of p-CA were also studied. A dynamic test indicated that the biodegradation had no lag phase at concentrations from 0 to 20mg/L in minimal medium culture fluids at vaccination of 15%, pH 7.0 and 32°C, and the growth of strain ycsd02 cells met the first-order kinetics.

Catechol 1,2-dioxygenase from the new aromatic compounds – Degrading Pseudomonas putida strain N6

This study aimed to characterization of catechol 1,2-dioxygenase from a Gram-negative bacterium, being able to utilize a wide spectrum of aromatic substrates as a sole carbon and energy source. Strain designated as N6, was isolated from the activated sludge samples of a sewage treatment plant at Bentwood Furniture Factory Jasienica, Poland. Morphology, physio-biochemical characteristics and phylogenetic analysis based on 16S rDNA sequence indicate that strain belongs to Pseudomonas putida. When cells of strain N6 grown on protocatechuate or 4-hydroxybenzoic acid mainly protocatechuate 3,4-dioxygenase was induced. The activity of catechol 1,2-dioxygenase was rather small. The cells grown on benzoic acid, catechol or phenol showed high activity of only catechol 1,2-dioxygenase. This enzyme was optimally active at 35 °C and pH 7.4. Kinetic studies showed that the value of K m and V max was 85.19 μM and 14.54 μM min −1 respectively. Nucleotide sequence of gene encoding catechol 1,2-dioxygenase in strain N6 has 100% identity with catA genes from two P. putida strains. The deduced 301-residue sequence of enzyme corresponds to a protein of molecular mass 33.1 kDa. The deduced molecular structure of the catechol 1,2-dioxygenase from P. putida N6 was very similar and characteristic for the other intradiol dioxygenases.

Hydrogen production by the newly isolated Clostridium beijerinckii RZF-1108

A fermentative hydrogen-producing strain, RZF-1108, was isolated from a biohydrogen reactor, and identified as Clostridium beijerinckii on the basis of the 16S rRNA gene analysis and physiobiochemical characteristics . The effects of culture conditions on hydrogen production by C. beijerinckii RZF-1108 were investigated in batch cultures. The hydrogen production and growth of strain RZF-1108 were highly dependent on temperature, initial pH and substrate concentration. Yeast extract was a favorable nitrogen source for hydrogen production and growth of RZF-1108. Hydrogen production corresponded to cell biomass yield in different culture conditions. The maximum hydrogen evolution, yield and production rate of 2209 ml H 2/l medium, 1.97 mol H 2/mol glucose and 104.20 ml H 2/g CDW h −1 were obtained at 9 g/l of glucose, initial pH of 7.0, inoculum volume of 8% and temperature of 35 °C, respectively. These results demonstrate that C. beijerinckii can efficiently produce H 2, and is another model microorganism for biohydrogen investigations.

Salt (NaCl)-Induced Modulation in some Key Physio-Biochemical Attributes in Okra (Abelmoschus esculentus L.)

Salt (NaCl)-induccd regulation of some key physio-biochemical characteristics in two okra (Abelmoschus esculentus L.) cultivars (Nirali and Posa Sawni) was examined under greenhouse conditions. Plants of both cultivars were subjected for 30 days to sand culture salinized with four salt levels [0 (control), 50, 100 and 150 mM NaCl] in Hoagland's nutrient solution. Salt stress significantly reduced the shoot and root fresh weights, transpiration rate, chlorophyll b content, net CO 2 assimilation (A), transpiration rate (E), while enhanced leaf and root Na + and Cl ― concentrations in both cultivars. In contrast, chlorophyll a content, stomatal conductance (g s ), leaf internal CO 2 (C i ), C i /C a ratio, water-use efficiency (A/E) and fluorescence characteristics such as photochemical quenching (qP), non-photochemical quenching (NPQ), efficiency of PS-II (F v /F m ), proline contents, and leaf and root K + , Ca 2 + and N contents remained almost unaffected in both lines due to salt stress. The efficiency of PSII (F v /F m ), A, chlorophyll b, root fresh weight and root N were higher in relatively salt tolerant cv. Nirali, whereas leaf Na + and root Cl ― were higher in cv. Posa Sawni. The relatively more reduction in growth in the cv. Posa Sawni was found to be associated with higher accumulation of Na + in its leaves and Cl ― in roots.

Biodegradation of deltamethrin and its hydrolysis product 3-phenoxybenzaldehyde by a newly isolated Streptomyces aureus strain HP-S-01

A newly isolated actinomycete strain HP-S-01 from activated sludge could effectively degrade deltamethrin and its major hydrolysis product 3-phenoxybenzaldehyde. Based on the morphological, cultural, physio-biochemical characteristics, and 16S rDNA sequence analysis, strain HP-S-01 was identified as Streptomyces aureus. Strain HP-S-01 was also found highly efficient in degrading cyfluthrin, bifenthrin, fenvalerate, fenpropathrin, permethrin, and cypermethrin. Strain HP-S-01 rapidly degraded deltamethrin without a lag phase over a wide range of temperature (18~38°C) and pH (5~10), and metabolized to produce α-hydroxy-3-phenoxy-benzeneacetonitrile and 3-phenoxybenzaldehyde by hydrolysis of the carboxylester linkage. The 3-phenoxybenzaldehyde was further oxidized to form 2-hydroxy-4-methoxy benzophenone resulting in its detoxification. No persistent accumulative product was detected by gas chromatography-mass spectrometry (GC/MS) analysis. Response surface methodology was used to optimize degradation conditions. Strain HP-S-01 completely removed 50~300 mg L(-1) deltamethrin within 7 days under the optimal degradation conditions. Furthermore, the biodegradation kinetics corresponded with the first-order model. Therefore, strain HP-S-01 is suitable for the efficient and rapid bioremediation of pyrethroid-contaminated environment.

Biodegradation of beta-cypermethrin and 3-phenoxybenzoic acid by a novel Ochrobactrum lupini DG-S-01

A newly isolated bacterium DG-S-01 from activated sludge utilized beta-cypermethrin (beta-CP) and its major metabolite 3-phenoxybenzoic acid (3-PBA) as sole carbon and energy source for growth in mineral salt medium (MSM). Based on the morphology, physio-biochemical characteristics, and 16S rDNA sequence analysis, DG-S-01 was identified as Ochrobactrum lupini. DG-S-01 effectively degraded beta-CP with total inocula biomass A590nm=0.1–0.8, at 20–40°C, pH 5–9, initial beta-CP 50–400mgL−1 and metabolized to yield 3-PBA leading to complete degradation. Andrews equation was used to describe the special degradation rate at different initial concentrations. Degradation rate parameters qmax, Ks and Ki were determined to be 1.14d−1, 52.06mgL−1 and 142.80mgL−1, respectively. Maximum degradation was observed at 30°C and pH 7.0. Degradation of beta-CP was accelerated when MSM was supplemented with glucose, beef extract and yeast extract. Studies on biodegradation in liquid medium showed that over 90% of the initial dose of beta-CP (50mgL−1) was degraded under the optimal conditions within 5d. Moreover, the strain also degraded beta-cyfluthrin, fenpropathrin, cyhalothrin and deltamethrin. These results reveal that DG-S-01 may possess potential to be used in bioremediation of pyrethroid-contaminated environment.

Comparative analysis of growth and physio-biochemical responses of Hydrilla verticillata to different sediments in freshwater microcosms

The long-term effect of Hydrilla verticillata to different dredged sediments was investigated in laboratory aquatic microcosms. Two kinds of lake sediments, i.e., fertile sludge and brown clay, which were acquired by deep or slight dredging and differed in their nutrients levels and particle sizes, were used as growth substrate. One year after H. verticillata seedlings were transplanted into the microcosms, growth and physio-biochemical characters of the plants were estimated. In our study, sludge sediment eventually promoted the increase of the biomass, shoot length, bifurcation, nitrogen, phosphorus, soluble protein content of H. verticillata, but not root number and root mass ratio. Additionally, the soluble sugar content was significantly lower in summer (August) in the sludge sediment. Sediment nutrients also increased photosynthetic pigment content, while POD and SOD activities were not affected. The fertile sludge and brown clay formed by different dredging are quite different, but both sediments could meet the requirement of H. verticillata during early growth stage. The fertile sediment after moderate dredge-up fit the growth of H. verticillata. The brown clay formed after excessive dredging showed a lack of nutrients and therefore led to the weak growth of the aquatic plants. It is concluded that moderate dredging was suitable for H. verticillata growth and for absorbing nitrogen and phosphorus from eutrophic fresh water. The experiment also suggested that submersed aquatic plant restoration in freshwater can be promoted by human assistance.