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11.
J. Ruiz‐Sanchez Z.R. Flores‐Bustamante L. Dendooven E. Favela‐Torres G. Soca‐Chafre J. Galindez‐Mayer L.B. Flores‐Cotera 《Journal of applied microbiology》2010,109(6):2144-2150
Aims: To determine in liquid (LF) and solid‐state fermentation (SSF) the effect of medium concentration on growth and Taxol produced by Nigrospora sp., a fungus isolated from the Mexican yew. Methods and Results: Nigrospora sp. was grown at different concentrations of the base culture medium M1D, i.e. two (2×), four (4×), six (6×) and eight times (8×) the base concentration. The titres of Taxol determined by competitive inhibition enzyme immunoassay increased with increasing medium concentration in LF and SSF but were higher in SSF in every medium concentration. The Taxol produced in SSF and LF with 8× medium was 221 and 142 ng l?1. The SSF gave also higher biomass, growth and sugar utilization than LF in every medium. The growth and sugar consumption were modelled by the logistic and the Pirt models, respectively. However, the Luedeking–Piret model was unsuitable for Taxol. Conclusions: The SSF surpassed LF in terms of Taxol, growth and sugar utilization; thus, it has significant advantages over LF. Significance and Impact of the Study: This is the first report on Taxol production by SSF and the first contribution to evaluate the influence of the medium on Taxol production in LF and SSF. 相似文献
12.
Alvarez-Bernal D Contreras-Ramos S Marsch R Dendooven L 《International journal of phytoremediation》2007,9(2):79-90
Phytoremediation is a cost-effective biotechnology for decontamination of polycyclic aromatic hydrocarbons (PAHs)-polluted soils. A greenhouse experiment was conducted to determine the growth of Mimosa monancistra, a N2-fixing leguminous plants, and its capacity to remove phenanthrene, anthracene, and benzo(a)pyrene (BaP)from soil. The PAHs decreased shoot and root dry biomass of M. monancistra 2.7- and 3.9-fold, respectively, compared to uncontaminated soil and inhibited nodule formation. The removal of phenanthrene and anthracene was similar in vegetated and unvegetated soil, but the dissipation of BaP was significantly faster in vegetated soil as compared to unvegetated soil after 14, 56, 70, and 90 d. After 90 d, dissipation of BaP was 96% in vegetated soil and 87% in unvegetated soil. Nitrification and ammonification were not affected by the addition of PAHs as concentrations of NH4+, NO2-, and NO3- were similar in contaminated and uncontaminated vegetated soil. Growth of M. monancistra was inhibited by contamination with hydrocarbons, but removal of BaP was accelerated in the rhizosphere. 相似文献
13.
Federico Antonio Gutiérrez Miceli Adan Domínguez Estudillo Miguel Abud Archila Teresa del Rosario Ayora Talavera Luc Dendooven 《In vitro cellular & developmental biology. Plant》2008,44(1):33-39
Renealmia mexicana (Klotzsch ex. Petersen) is a tropical plant found in southern México with an ornamental value and a potential source of curcuminoids.
Its distribution in Chiapas has decreased because of deforestation and low propagation and germination rate, so a protocol
for in vitro propagation was developed. An orthogonal experimental design of L9 (34) in triplicate was used to investigate the effect of 6-benzyl adenine (BA), indole butyric acid (IBA), silver nitrate (AgNO3), and sucrose on shoot, root, and leaf development of plantlets grown in vitro. Plantlets with well-developed shoots and roots were transferred to pots containing a mixture of peat moss and agrolite for
hardening before transfer to soil. The Murashige and Skoog (Physiol. Plant. 15:473–497, 1962) mineral medium (MS) supplemented
with 4.4 μM BA, 2.5 μM IBA, 11.7 μM AgNO3y and 5.5% (w/v) sucrose gave most shoots, 8.9 μM BA, 2.5 μM IBA, 17.7 μM AgNO3 and 5.5% (w/v) sucrose most roots, and 8.9 μM BA, 4.9 μM IBA, 11.7 μM AgNO3 and 3.0% (w/v) sucrose most leaves, although other combinations were statistically equivalent in each case. Sucrose was the factor that
most explained the variation in the promotion of shoots, roots, and leaves. The protocol developed resulted in up to 100%
survival when plantlets were transferred to soil using AgNO3, confirming that hardening of plantlets in vitro using hormonal stimulation was a suitable strategy to improve acclimatization. 相似文献
14.
Phylogenetic analysis of the archaeal community in an alkaline-saline soil of the former lake Texcoco (Mexico) 总被引:1,自引:0,他引:1
Valenzuela-Encinas C Neria-González I Alcántara-Hernández RJ Enríquez-Aragón JA Estrada-Alvarado I Hernández-Rodríguez C Dendooven L Marsch R 《Extremophiles : life under extreme conditions》2008,12(2):247-254
The soil of the former lake Texcoco is an extreme environment localized in the valley of Mexico City, Mexico. It is highly
saline and alkaline, where Na+, Cl−, HCO3− and CO32− are the predominant ions, with a pH ranging from 9.8 to 11.7 and electrolytic conductivities in saturation extracts from
22 to 150 dS m−1. Metagenomic DNA from the archaeal community was extracted directly from soil and used as template to amplify 16S ribosomal
gene by PCR. PCR products were used to construct gene libraries. The ribosomal library showed that the archaeal diversity
included Natronococcus sp., Natronolimnobius sp., Natronobacterium sp., Natrinema sp., Natronomonas sp., Halovivax sp., “Halalkalicoccus jeotgali” and novel clades within the family of Halobacteriaceae. Four clones could not be classified. It was found that the archaeal
diversity in an alkaline-saline soil of the former lake Texcoco, Mexico, was low, but showed yet uncharacterized and unclassified
species.
César Valenzuela-Encinas and Isabel Neria-González contributed equally to this publication. 相似文献
15.
Juan M. Bello-López Cristina A. Domínguez-Mendoza Arit S. de León-Lorenzana Laura Delgado-Balbuena Yendi E. Navarro-Noya Selene Gómez-Acata Analine Rodríguez-Valentín Victor M. Ruíz-Valdiviezo Marco Luna-Guido Nele Verhulst Bram Govaerts Luc Dendooven 《Extremophiles : life under extreme conditions》2014,18(4):733-743
After chloroform fumigating an arable soil, the relative abundance of phylotypes belonging to only two phyla (Actinobacteria and Firmicutes) and two orders [Actinomycetales and Bacillales (mostly Bacillus)] increased in a subsequent aerobic incubation, while it decreased for a wide range of bacterial groups. It remained to be seen if similar bacterial groups were affected when an extreme alkaline saline soil was fumigated. Soil with electrolytic conductivity between 139 and 157 dS m?1, and pH 10.0 and 10.3 was fumigated and the bacterial community structure determined after 0, 1, 5 and 10 days by analysis of the 16S rRNA gene, while an unfumigated soil served as control. The relative abundance of the Firmicutes increased in the fumigated soil (52.8 %) compared to the unfumigated soil (34.2 %), while that of the Bacteroidetes decreased from 16.2 % in the unfumigated soil to 8.8 % in the fumigated soil. Fumigation increased the relative abundance of the genus Bacillus from 14.7 % in the unfumigated soil to 25.7 %. It was found that phylotypes belonging to the Firmicutes, mostly of the genus Bacillus, were dominant in colonizing the fumigated alkaline saline as found in the arable soil, while the relative abundance of a wide range of bacterial groups decreased. 相似文献
16.
Yohanna Sarria-Guzmán María Patricia López-Ramírez Yosef Chávez-Romero Erick Ruiz-Romero Luc Dendooven Juan Manuel Bello-López 《Current microbiology》2014,68(5):581-586
Forty-six Aeromonas spp. strains were isolated from fresh fish and investigated for their antimicrobial susceptibility, detection of Class 1 integrons by PCR, and arrangement of gene cassettes. Selected isolates were further characterized by enterobacterial repetitive intergenic consensus-PCR. Twenty isolates were found to carry Class 1 integrons. Amplification of the variable regions of the integrons revealed diverse bands ranging in size from 150 to 1,958 pb. Sequence analysis of the variable regions revealed the presence of several gene cassettes, such as adenylyl transferases (aadA2 and aadA5), dihydrofolate reductases (dfrA17 and dfrA1), chloramphenicol acetyl transferase (catB3), β-lactamase (oxa2), lincosamide nucleotidil transferase (linF), aminoglycoside-modifying enzyme (apha15), and oxacillinase (bla OXA-10). Two open reading frames with an unknown function were identified as orfC and orfD. The aadA2 cassette was the most common integron found in this study. Interestingly, five integrons were detected in the plasmids that might be involved in the transfer of resistance genes to other bacteria. This is a first report of cassette encoding for lincosamides (linF) resistance in Aeromonas spp. Implications on the incidence of integrons in isolates of Aeromonas spp. from fresh fish for human consumption, and its possible consequences to human health are discussed. 相似文献
17.
Influence of permanent raised bed planting and residue management on physical and chemical soil quality in rain fed maize/wheat systems 总被引:1,自引:1,他引:1
Densely populated, intensively cropped highland areas in the tropics and subtropics are prone to erosion and declining soil
fertility, making agriculture unsustainable. Conservation agriculture in its version of permanent raised bed planting with
crop residue retention has been proposed as an alternative wheat production system for this agro-ecological zone. A five years
field experiment comparing permanent and tilled raised beds with different residue management under rainfed conditions was
started at El Batán (Mexico) (2,240 m asl; 19.31°N, 98.50°W; Cumulic Phaeozem) in 1999. The objective of this study was to
determine the soil quality status after five years of different management practices. The K concentration was 1.65 times and
1.43 times larger in the 0–5 cm and 5–20 cm profiles, respectively, for permanent raised beds compared to conventionally tilled
raised beds. The Na concentration showed the opposite trend. Sodicity was highest for conventionally tilled raised beds and
for permanent raised beds it increased with decreasing amounts of residue retained on the surface. Permanent raised beds with
full residue retention increased soil organic matter content 1.4 times in the 0–5 cm layer compared to conventionally tilled
raised beds with straw incorporated and it increased significantly with increasing amounts of residue retained on the soil
surface for permanent raised beds. Soil from permanent raised beds with full residue retention had significantly higher mean
weight diameter for wet and dry sieving compared to conventionally tilled raised beds. Permanent raised beds with full residue
retention had significantly higher aggregate stability compared to those with residue removal. A lower aggregation resulted
in a reduction of infiltration. Principal component analysis (PCA) was performed using these soil physicochemical variables
that were significantly influenced by tillage or residue management. The PC1 and PC2 separated the conventionally tilled raised
beds from the permanent raised beds and PC3 separated permanent raised beds with at least partial residue retention from permanent
raised beds with no residue retention. These clear separations suggest that tillage and residue management have an effect
on soil processes. The research indicates that permanent raised bed planting increases the soil quality and can be a sustainable
production alternative for the (sub)tropical highlands. Extensive tillage with its associated high costs can be reduced by
the use of permanent raised beds while at least partial surface residue retention is needed to insure production sustainability. 相似文献
18.
Erick Ruiz-Romero César Valenzuela-Encinas María Patricia López-Ramírez María de los Angeles Coutiño-Coutiño Rodolfo Marsch Luc Dendooven 《Archives of microbiology》2013,195(2):145-151
A new haloalkaliphilic archaeon, strain B4T, was isolated from the former lake Texcoco in Mexico. The cells were Gram-negative, pleomorphic-shaped, pink to red pigmented and aerobic. Strain B4T required at least 2.5 M NaCl for growth, with optimum growth at 3.4 M NaCl. It was able to grow over a pH range of 7.5–10.0 and temperature of 25–50 °C, with optimal growth at pH 9 and 37 °C. Cells are lysed in hypotonic treatment with less than 1.3 M NaCl. The major polar lipids of strain B4T were phosphatidylglycerol and methyl-phosphatidylglycerophosphate. Phospholipids were detected, but not glycolipids. The nucleotide sequence of the 16S rRNA gene revealed that the strain B4T was phylogenetically related to members of the genus Natronorubrum. Sequence similarity with Natronorubrum tibetense was 96.28 %, with Natronorubrum sulfidifaciens 95.06 % and Natronorubrum sediminis 94.98 %. The G+C content of the DNA was 63.3 mol%. The name of Natronorubrum texcoconense sp. nov. is proposed. The type strain is B4T (=CECT 8067T = JCM 17497T). 相似文献
19.
Amaya-Delgado L Vega-Estrada J Flores-Cotera LB Dendooven L Hidalgo-Lara ME Montes-Horcasitas MC 《Applied microbiology and biotechnology》2006,70(4):477-481
The effect of cell density on xylanolytic activity and productivity of Cellulomonas flavigena was evaluated under two different culturing conditions: fed-batch culture with discontinuous feed of sugar cane bagasse (SCB;
condition 1) and glycerol fed-batch culture followed by addition of SBC as xylanases inducer (condition 2). The enzymatic
profile of xylanases was similar in both systems, regardless of the initial cell density at time of induction. However, the
xylanolytic activity changed with initial cell density at the time of induction (condition 2). The maximum volumetric xylanase
activity increased with increased initial cell density from 4 to 34 g l−1 but decreased above this value. The largest total volumetric xylanase productivity under condition 2 (1.3 IU ml−1 h−1) was significantly greater compared to condition 1 (maximum 0.6 IU ml−1 h−1). Consequently, induction of xylanase activity by SCB after growing of C. flavigena on glycerol at intermediate cell density can be a feasible alternative to improve activity and productivity of xylanolytic
enzymes. 相似文献
20.
Conservation agriculture, increased organic carbon in the top-soil macro-aggregates and reduced soil CO2 emissions 总被引:1,自引:0,他引:1
Mariela Fuentes Claudia Hidalgo Jorge Etchevers Fernando De León Armando Guerrero Luc Dendooven Nele Verhulst Bram Govaerts 《Plant and Soil》2012,355(1-2):183-197