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1.
Isolation,Identification and Screening of Manganese Solubilizing Fungi From Low-Grade Manganese Ore Deposits 总被引:1,自引:0,他引:1
The present investigation reports the isolation, molecular identification and screening of manganese (Mn) solubilizing fungal strains from low-grade Mn mine tailings. Six morphologically distinct Mn solubilizing fungal strains were isolated on MnO2-supplemented agar plates with Mn concentration of 0.1% (w/v). The biochemical characterization of the isolated fungal strains was carried out. The molecular identification by internal transcribed spacer (ITS) sequencing identified the strains as Aspergillus terreus, Aspergillus oryzae, Penicillium sp., Penicillium sp., Penicillium daleae and Penicillium sp. with GenBank accession numbers KP309809, KP309810, KP309811, KP309812, KP309813 and KP309814, respectively. The ability of the isolated fungal strains to tolerate and solubilize Mn was investigated by subculturing them on Mn-supplemented plates with concentration ranging from 0.1 to 0.5% (w/v). Mn solubilizing ability of the fungal isolates is possibly due to the mycelia production of biogenerated organic acids such as oxalic acid, citric acid, maleic acid and gluconic acid as revealed by ion chromatography. Our investigation signifies the role of fungi in biotransformation of insoluble Mn oxide. 相似文献
2.
Available phosphate content of an alluvial soil as influenced by inoculation of some isolated phosphate-solubilizing micro-organisms 总被引:2,自引:0,他引:2
Summary Among several phosphate-solibilizing micro-organisms isolated from an alluvial soil (Fluvaquent) in sucrose-Ca3(PO4)2 agar plates, two fungal strains, ACF2 (Aspergillus candidus) and ACF1 (A. fumigatus) two bacterial strains, ACB5 (Bacillus firmus B-7650) and ACB6 (B. firmus B-7651) and one actinomycete strain, ACS6 (Streptomyces sp.) were efficient solubilizers, solubilizing 297.0, 288.3, 49.0, 45.8 and 29.0 μg of P as free PO4
−3, respectively, containing 15 mg insoluble P from Ca3(PO4)2 in broth. Solubilization was lesser from AlPO4 and FePO4. The isolates producing oxalic and tartaric acids without or with citric acid showed higher ability of solubilizing insoluble
inorganic phosphates.
All the above isolates possessed the ability of solubilizing rock phosphate in considerable amounts, ACF1 (A. fumigatus) being the highest (31.5 μg), while ACB6 (B. firmus B-7651) and both the aspergilli also possessed cellulose-decomposing ability in addition.
Inoculation of the isolates, in a flask culture experiment, had no significant effect on the accumulation of available phosphorus
in soil even when amended with rock phosphate (RP), farm yard manure (FYM), (FYM+RP), rice straw (RS) and (RS+RP). Nevertheless,
the overall performance of ACF2 (A. candidus) and ACB6 (B. firmus B-7651) was better than that of the others, in this respect, while ACB5 (B. firmus B-7650) and ACF1 (A. fumigatus) intensified the enhancing effect of FYM and RS. Partial sterilization, by autoclaving, of the soil had no significant effect
on available phosphorus content of the soil irrespective of any inoculation. 相似文献
3.
In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant,
depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain
Bacillus subtilis 168. The growth and protein release of model Gram (−) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations
supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in
cell surface hydrophobicity and permeability of some Gram (+) and Gram (−) isolates in the presence of rhamnolipid biosurfactant
were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic
than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase
in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell
permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute
to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties
of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments. 相似文献
4.
Conventional leaching methods for manganese (Mn) recovery require strong acids and are threatening to the environment. Alternatively, the use of microbes for Mn recovery is environment friendly in nature. The present investigation compares the capacity of pure and mixed cultures of native bacterial strains for bioleaching of low-grade Mn ores. The ability of the isolated microorganisms to recover Mn was evaluated in shake flasks for 20 days under optimized conditions of pulp density (2%), sucrose concentration (2 g/100 mL), initial pH 6.5, and 30°C incubation temperature. In pure culture form, Acinetobacter sp. MSB 5 (70%) was found to have a higher bioleaching potential than Lysinibacillus sp. MSB 11 (67%). Mixed culture of Acinetobacter sp. MSB 5 and Lysinibacillus sp. MSB 11 was found to perform better than the pure cultures with 74% extraction of Mn. The presence of mixed culture increased the dissolution rate and the recovery percentage of Mn. The respective growth pattern of the cultures was in synchronization to their Mn bioleaching performances. This study underlines the importance of mixed cultures and Mn solubilizing activity of native bacterial strains for efficient Mn biorecovery. 相似文献
5.
Massimiliano Marvasi Kimberley L. Gallagher Lilliam Casillas Martinez William C. Molina Pagan Ronald E. Rodríguez Santiago Gloria Castilloveitía Vega 《Geomicrobiology journal》2013,30(10):916-924
B4 precipitation medium has been used as the preferred medium for studying mineral precipitation using bacterial strains in vitro since pioneer studies were performed by Boquet and coworkers in 1973. Using this medium, several authors have demonstrated that some environmental isolates were able to precipitate minerals, yet others did not. The main goal of the current study is to understand whether pH and buffer conditions would have a significant effect on mineral precipitation results for environmental isolates grown on B4. For this study, a total of 49 strains isolated from natural environments from Puerto Rico were grown on B4 plates, and their CaCO3 precipitation potential was investigated. Our findings revealed a strong correlation between a lack of CaCO3 precipitation and the acidification of the B4 plates by the colonies. The ability to precipitate CaCO3 could be restored by buffering the B4 medium to a pH of 8.2. Buffering capacity of the medium was proposed to be involved in CaCO3 precipitation: acid-base titrations conducted on the individual ingredients of B4 showed that yeast extract has a poor buffering capacity between pH 6.5–7.5. This pH range corresponds to the pH of B4 plates [6.87 (±0.05)] prior to the inoculation. This might explain why B4 is such a good precipitation medium: a small variation in the H+/OH? balance during microbial growth and precipitation produces rapid changes in the pH of the medium. Finally, an amorphous matrix was distributed within 90% of the examined crystals generated on B4 medium by the environmental strains. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental file. 相似文献
6.
Muhammed E. El-Hadad Magdi I. Mustafa Shawky M. Selim Ahmed E. A. Mahgoob Tarek S. El-Tayeb Norhan H. Abdel Aziz 《World journal of microbiology & biotechnology》2010,26(12):2249-2256
Representative soil samples were collected from soil apart and the rhizosphere of different plant varieties grown in five
Egyptian Governorates. The presence of plant parasitic nematodes (PPN) and free living nematodes (FLN) in the collected samples
were estimated. In addition, one hundred and 65 bacterial cultures which well known as biofertilizers (some are able to fix
nitrogen and the others solubilize either phosphate or potassium) were isolated. The isolated bacteria were screened depending
on their rate of growth. Thirty-five cultures of fast growing nitrogen fixing bacteria (NFB), phosphate solubilizing bacteria
(PSB) and potassium solubilizing bacteria (KSB) and their cultural filtrates were tested in vitro as biocontrol agents against
the second stage juvenile (J2s) of the Meloidogyne incognita. In general, higher mortality percentages of nematodes were recorded by bacterial cultures than their comparative cultural
filtrates. The highest mortality percentages were recorded by cultures of NFB7, PSB2 and KSB2 (100% at dilution 1/10), while
it was 99.3, 99 and 97.8% at dilution 1/100, respectively. NFB7 exhibited a high nitrogen fixation rate (4.2 μmole N2/mL/h), while PSB2 and KSB2 effectively solubilized phosphate and potassium comparing with the control treatments (1.94 fold
of available phosphate and 2.0 fold of available potassium, respectively). NFB7, PSB2 and KSB2 isolates showed the highest
protease, gelatinase and chitinase activities which were thought responsible for their nematicidal effect. The three bacterial
isolates were identified as Paenibacillus polymyxa, Bacillus megaterium and Bacillus circulans, respectively. 相似文献
7.
Eduardo Valencia-Cantero Erasto Hernández-Calderón Crisanto Velázquez-Becerra Joel E. López-Meza Ruth Alfaro-Cuevas José López-Bucio 《Plant and Soil》2007,291(1-2):263-273
Iron (Fe) is an essential element for plant growth and development. Some plant growth-promoting rhizobacteria can increase
Fe uptake by plants through reduction of Fe(III) to Fe(II) at the root surface. The aim of this work was to identify novel
bacterial strains with high Fe(III) reduction ability and to evaluate their role in plant Fe uptake. Four bacterial strains
(UMCV1 to UMCV4) showing dissimilatory Fe-reducing activity were isolated from the rhizosphere of bean and maize plants and
further identified by 16S rDNA amplification and sequence analysis. From these analyses, UMCV1 and UMCV2 isolates were identified
as Bacillus megaterium and Arthrobacter spp., respectively, whereas UMCV3 and UMCV4 were identified as Stenotrophomonas maltophilia. All four isolates showed Fe reduction in a nonflooded soil and when associated with roots of bean plants grown in alkaline
soil or in mineral medium. In addition, the bacterial isolates were able to stimulate plant growth in vitro and on a broad
level, plants grown in inoculated soil were generally bigger and with higher Fe content than those grown in sterilized soil.
These results indicate that bacterial species isolated from the rhizosphere of bean and maize plants contribute significantly
to Fe uptake by plants likely through increased Fe(III) reduction in the rhizosphere. 相似文献
8.
Camille Calzada Urquiza Ivan Arvizu Hernández Julio Alfonso Cruz Medina Miguel Angel Ramos López Jaime Pérez Cruz Raquel Louvan Rivera Zarazúa 《Geomicrobiology journal》2017,34(2):176-182
In this work, mercury-resistant bacterial strains were isolated from the rhizosphere of an apple orchard, growing in a soil with high levels of mercury (Nuevo San Joaquin, Queretaro State, Mexico). Analysis of the soil in this region by the Cold Vapor Atomic Absortion Spectroscopy method showed that it contained 637 ± 51 mg mercury per kg. Mercury accumulation by fresh apples from this orchard amounted to 15.44 ± 4.33 mg/kg. The bacterial isolates were identified by application of proteomic technique of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). They were found to be strains of Bacillus muralis and Bacillus simplex. All strains showed the ability to catalyze the volatilization of Hg as measured via the nonradioactive X-ray method. In all strains merR and merA genes were detected by polymerase chain reaction. Nucleotide sequence analysis showed that merR from B. simplex was 435 bp in length and that its sequence was similar to merR sequences reported for other bacteria such as Cupriavidus, Ralstonia, Pseudomonas and Serratia. To our knowledge, this is the first report of mercury-resistant Bacillus strains isolated from the rhizosphere of an apple orchard and the first merR gene sequence from such Bacilli. 相似文献
9.
Selection and identification of bacteria isolated from waste crude oil with polycyclic aromatic hydrocarbons removal capacities 总被引:1,自引:0,他引:1
Toledo FL Calvo C Rodelas B González-López J 《Systematic and applied microbiology》2006,29(3):244-252
Fifteen bacterial strains isolated from solid waste oil samples were selected due to their capacity of growing in the presence of hydrocarbons. The isolates were identified by PCR of the 16S rDNA gene using fD1 and rD1 primers. The majority of the strains belonged to genera Bacillus, Bacillus pumilus (eight strains) and Bacillus subtilis (two strains). Besides, three strains were identified as Micrococcus luteus, one as Alcaligenes faecalis and one strain as Enterobacter sp. Growth of the above-mentioned strains in mineral liquid media amended with naphthalene, phenanthrene, fluoranthene or pyrene as sole carbon source was studied and our results showed that these strains can tolerate and remove different polycyclic aromatic hydrocarbons that may be toxic in the environment polluted with hydrocarbons. Finally, the capacity of certain strains to emulsify octane, xilene, toluene, mineral oil and crude oil, and its ability to remove hydrocarbons, look promising for its application in bioremediation technologies. 相似文献
10.
Atya Kapley Sameera N. Siddiqui Hemant J. Purohit 《World journal of microbiology & biotechnology》2007,23(6):879-882
This study reports the identification and demonstration of an organism with antimicrobial activity isolated from activated
biomass of an effluent treatment plant (ETP) treating wastewater containing pesticides. While assessing the heterotrophic
diversity of biomass collected from ETP, clear zones were observed on Luria Bertani plates. The bacterial isolate producing
the zone as well as the bacterial cells surrounding the zone were isolated and purified by sub-culturing. Both isolates were
identified by partial sequencing of the 16S rDNA clone. Presence of antimicrobial activity was demonstrated against various
laboratory strains, isolated from different treatment plants and also against waterborne pathogens. The isolate that produced
antimicrobial activity was identified as Bacillus subtilis strain HPC248 and the sensitive strain was identified as Bacillus sphaericus strain HPC249. 相似文献
11.
Mette Burmlle Kaare Johnsen Waleed Abu Al-Soud Lars Hestbjerg Hansen Sren Johannes Srensen 《Journal of microbiological methods》2009,79(2):166-173
Traditional methods for bacterial cultivation recover only a small fraction of bacteria from all sorts of natural environments, and attempts have been made to improve the bacterial culturability. Here we describe the development of a cultivation method, based on the embedment of pure bacterial cultures in between two layers of agar. Plates containing either embedded Pseudomonas putida or Arthrobacter globiformis resulted in higher numbers of CFUs of soil bacteria (21% and 38%, respectively) after 833 h of incubation, compared to plates with no embedded strain. This indicates a stimulatory effect of the bacterial pure cultures on the cultivation of soil bacteria. Analysis of partial 16S rRNA gene sequences revealed a phylogenetical distribution of the soil isolates into 7 classes in 4 phyla. No difference was observed at the phylum or class level when comparing isolates grouped according to embedded strain. The number of isolates belonging to the same class as the embedded strain was reduced in comparison to that of plates with no embedded strain, indicating that intercellular signalling was unlikely to cause the observed stimulatory effect. Significantly higher fractions of isolates with less than 97% sequence homology to known sequenced isolates in GenBank were recovered from plates with embedded strains than from those without, which indicate a higher number of potential novel soil isolates. This approach for cultivation is therefore a feasible alternative or supplement to traditional cultivation on agar plates in order to enhance bacterial culturability. 相似文献
12.
Scoaris Dde O Colacite J Nakamura CV Ueda-Nakamura T de Abreu Filho BA Dias Filho BP 《Antonie van Leeuwenhoek》2008,93(1-2):111-122
Aeromonas isolates from tap water, mineral water, and artesian well water were investigated for their ability to produce different
potential virulence factors or markers such as hemolysins, cytotoxins, phospholipase, DNase, hydrophobicity and their ability
to adhere to epithelial cells and to abiotic surfaces. The susceptibility to antibiotics of Aeromonas isolates was also examined. Majority of the isolates displayed hemolytic activity against sheep erythrocytes, while only
7 of the 23 Aeromonas strains displayed DNase activity and 4 of the 23 Aeromonas strains tested were regarded as positive for phospholipase production. Most of the isolates showed cytotoxic activities in
culture filtrate dilutions at titer of 1/8 or lower. No general relation between the strain isolated and the ability to interact
with epithelial cells could be established. Using the bacterial adherence to hydrocarbons method, most of the strains were
classified as highly hydrophilic. All five Aeromonas jandaei strains isolates, 9 of the 12 Aeromonas sp strains and four of the five Aeromonas hydrophila were multidrug resistant. The most active antimicrobial was ciprofloxacin (susceptible in 100% of the isolates), and the
least active antibiotic was ampicillin (resistance in 92% of the isolates). The majority of the isolates tested were not killed
by chlorine at 1.2 mg/l. Whether the high tolerance to chlorine of Aeromonas isolates can be linked to greater virulence is not know. 相似文献
13.
Recep Kotan Akif Okutucu Arzu Ala Görmez Kenan Karagoz Fatih Dadasoglu İsa Karaman İsmet Hasanekoglu Şaban Kordali 《Journal of Phytopathology》2013,161(3):165-171
This study was carried out to identify pathogenic bacteria and fungi on mistletoe (Viscum album L.) and investigate their potential use in biological control of this parasitic plant. For this purpose, a total of 48 fungal isolate and 193 bacterial strains were isolated from contaminated V. album during the summers 2005–2006. The isolated bacterial strains and fungal isolates were identified by using the Sherlock Microbial Identification System (MIS; Microbial ID, Newark) and microscopic methods, respectively. The bacterial strains that induced hypersensitive reaction (HR) on tobacco (Nicotiana tabacum L.) and fungal isolates were tested for pathogenicity on young shoots of mistletoe by using injection methods. The pathogenic bacterial strains and fungal isolates were also tested for their activity against mistletoe using spray methods. Five bacterial strains (two Burkholderia cepacia, one each of Bacillus megaterium, Bacillus pumilus and Pandoraea pulminicola) were HR and pathogenicity positive when injected but none of them when sprayed on mistletoe. When fungi were injected, 32 isolates were pathogenic but only thirteen when sprayed on mistletoe. Alternaria alternata VA?‐202, VA?‐205, VA?‐217 and Acremonium kiliense VA‐11 fungal isolates were the most effective ones and caused strong disease symptoms on mistletoe. The present study is the first report on the efficiency of potential biocontrol agents against mistletoe in Turkey. 相似文献
14.
Twenty-three bacterial isolates were screened for their mineral phosphate–solubilizing (MPS) ability on Pikovskaya and National
Botanical Research Institute’s phosphate (NBRIP) agar. The majority of the isolates exhibited a strong ability to solubilize
hydroxyapatite in both solid and liquid media. The solubilization in liquid medium corresponded with a decrease in the pH
of the medium. Serratia marcescens GPS-5, known for its biocontrol of late leaf spot in groundnut, emerged as the best solubilizer. S. marcescens GPS-5 was subjected to ethyl methanesulfonate (EMS) mutagenesis, and a total of 1700 mutants, resulting after 45 minutes
of exposure, were screened on buffered NBRIP medium for alterations in MPS ability compared with that of the wild type. Seven
mutants with increased (increased-MPS mutants) and 6 mutants with decreased (decreased-MPS mutants) MPS ability were isolated.
All seven increased-MPS mutants were efficient at solubilizing phosphate in both solid and liquid NBRIP medium. Among the
increased-MPS mutants, EMS XVIII Sm-35 showed the maximum (40%) increase in the amount of phosphate released in liquid medium compared with wild-type S. marcescens GPS-5, therefore, it would be a useful microbial inoculant in groundnut cultivation. EMS III Sm W, a nonpigmented mutant, showed the lowest solubilization of phosphate among the 6 decreased-MPS mutants. 相似文献
15.
AbstractPhosphate solubilizing bacteria (PSB) can convert insoluble form of phosphorous (P) to an available form which is a major concern in Indian agriculture. In this study, 21 isolates having phosphate solubilizing capability were isolated from different regions of Lucknow, India. Among all, six efficient PSB were confirmed by using in vitro P estimation and 16S rRNA universal primers. The similarity detection was done using random amplified polymorphic DNA (RAPD) finger printing for genotyping the PSB isolates and to determine genetic relatedness between them. Twenty different OPA primers were tested among which four primers produced prominent, highly reproducible, and polymorphic bands. An average of 10.5 polymorphic bands per primer with the amplified DNA fragments ranging from 200 to 2000?bp in size. A dendrogram constructed from these data indicated 25–76% homology. Highest similarity was found in between Bacillus anthracis and Bacillus cereus with 33.8% similarity while least dissimilarity was found in B. anthracis and Pseudomonas fragi with 12% of similarity. These findings provide that there is a great genetic diversity between bacterial isolates from different geographical regions and RAPD can be used as a specific, time consuming and also proves as a reliable molecular tool which helps in strain level discrimination. 相似文献
16.
Syed Azfar Hussain Shiv O. Prasher Martin Chenier Gitanjali Arya 《World journal of microbiology & biotechnology》2011,27(9):2061-2069
Nitrate-N-removing bacterial strains were isolated from a constructed wetland soil treated with three ionophoric antibiotics:
monensin, salinomycin and narasin. Five isolates were selected after initial screening for nitrogen removing potential. Nucleotide
sequence analysis of the 16S rRNA gene showed that these isolates were highly similar to Bacillus, and Pseudomonas species. The isolates were assessed for their ability to grow in the presence of ionophoric antibiotics. All strains were
found to withstand these pharmaceuticals. In particular, Bacillus subtilis strain BRAZ2B was found to thrive in the drug-exposed wetland environment, showing higher nitrate removal rate than the uninoculated
control. The strains were also assessed for nitrogen removal potential under three different C/N ratios: 4, 8 and 12; optimum
removal efficiency was observed at C/N 8 for most isolates. 相似文献
17.
Bacterial strains with ability to suppress Colletotrichum falcatum were isolated from the rhizosphere of sugarcane. Thirty nine candidates, chosen on the basis of in vitro antagonism, inhibited
C. falcatum growth by 15–65% on test plates. Twenty two isolates causing 50% or more in vitro inhibition were screened for their root
colonization ability and biocontrol activity on micropropagated sugarcane plants under greenhouse conditions. Twelve strains
suppressed red rot infection in plantlets, but no significant correlation was observed between in vitro pathogen inhibition
and in vivo disease suppression. However, isolates showing root colonization over 5.2 log10 CFU g−1 of soil showed highest suppression of C. falcatum and reduction of red rot disease. Six strains with the capability to maintain a significant population in the sugarcane rhizosphere
and with a high potential to control red rot were identified by 16S rDNA as Ochrobacterum intermedium NH-5, Pseudomonas putida NH-50, Bacillus subtilis NH-100, Bacillus subtilis NH-160, Bacillus sp NH-217 and Stenotrophomonas maltophilia NH-300. 相似文献
18.
Carlos Eduardo Barragán Marco Antonio Márquez Mark Dopson 《Geomicrobiology journal》2020,37(7):682-689
AbstractInactive mines provide a great source of bacterial diversity for studying acidophilic communities and their biotechnological applications, but prospecting of these anthropogenic environments in Colombia has been limited. Conventional microbiological methods were used to isolate acidophilic bacterial strains from effluents emanating from the Colombian gold mine ‘El Zancudo’ (Titiribí, Antioquia). Despite the drainage waters having circumneutral pH, all of the isolated strains were phylogenetically related to the extreme acidophile Acidithiobacillus genus. However, based upon 16S rRNA gene sequences the mesophilic sulfur-oxidizing indigenous strains could not be assigned to a species. Pure cultures were selected by screening in medium with soluble inorganic arsenic (III) and their mineral-oxidative activity was evaluated at 30?°C in Erlenmeyer flasks with arsenopyrite ore under rotary shaking conditions. The indigenous strains were able to catalyze arsenopyrite oxidation in a mixed culture with a pulp density of 10%, maintaining their growth in the presence of >80?mM leached arsenic. This research provides information regarding the isolation of arsenic resistant bacterial communities from neutral effluents from El Zancudo mine and the possibility of the isolated strains to be useful in the biooxidation pretreatment of refractory gold-bearing arsenopyrite ores and concentrates. 相似文献
19.
Catello Pane Domenica Villecco Francesco Campanile Massimo Zaccardelli 《Biocontrol Science and Technology》2012,22(12):1373-1388
A stepwise screening strategy made it possible to identify five new Bacillus spp. strains for biocontrol of Rhizoctonia solani, Sclerotinia minor and Fusarium solani. In vitro and in vivo biocontrol activity and M13-PCR DNA-fingerprinting led to the selection of these valuable biological control agents (BCAs) from a wide collection of over 250 candidates. At the end of this selection, the highest potential antagonists were identified at species level by 16S-rRNA gene sequence analysis, and results assigned them to Bacillus subtilis group as Bacillus amyloliquefaciens- and Bacillus methylotrophicus-related strains. In the current study, spore-forming bacteria provided substantial biocontrol of telluric diseases on cress and other different host plants. The strains named 15S and 09C were effective in disease control on Brassica oleracea/R. solani pathosystem, whereas Sclerotinia drop of lettuce was reduced by treatments with the strains 17S and 08C. Finally, the strains 17S and 12S were equally effective to control potato Fusarium rot. The evident zone of inhibition seen in dual culture plates suggested antibiosis-like antagonisms as the main mechanisms used by these bacterial isolates in interaction with the pathogens. Additionally, the API-ZYM method revealed constitutive activity of certain extracellular enzymes that could be involved in plant fortification. Bacillus strains isolated from compost and compost-amended soils are promising BCAs that have potential for practical application as biofungicides. 相似文献
20.
Mark Hernandez Eric A. Marchand Deborah Roberts Jordan Peccia 《International biodeterioration & biodegradation》2002,49(4):748
Culture-dependent studies have implicated sulfur-oxidizing bacteria as the causative agents of concrete corrosion in sanitary sewers. Thiobacillus species are often considered the major representative of the acid-producing bacteria in these environments, and members of the genus Acidiphilium have been implicated to support their growth. Active populations of selected Thiobacillus, Leptospirillum, and Acidiphilium species were compared to total bacterial populations growing on the surfaces of corroding concrete using three oligonucleotide probes that have been confirmed to recognize unique sequences of 16S rRNA in the following acidophilic bacteria: Thiobacillus ferrooxidans and Thiobacillus thiooxidans (probe: Thio820), Leptospirilium ferrooxidans (Probe: Lept581) and members of the genus Acidiphilium (probe: Acdp821). With these genetic probes, fluorescent in situ hybridizations (FISH) were used to identify and enumerate selected bacteria in homogenized biofilm samples taken from the corroding crowns of concrete sewer collection systems operating in Houston, Texas, USA. Direct epifluorescent microscopy demonstrated the ability of FISH to identify significant numbers of active acidophilic bacteria among concrete particles, products of concrete corrosion (e.g. CaSO4), and other mineral debris. As judged by FISH analyses with the species-specific probe Thio820, and a domain-level probe that recognizes all Bacteria (Eub338), T. ferrooxidans and T. thiooxidans comprised between 12% and 42% of the total active Bacteria present in corroding concrete samples. Although both Acidiphilium and Leptospirillum have also been postulated to have ecological significance in acidic sulfur-oxidizing environments, neither genera was detected using genus-specific probes (Lept581 and Acdp821). 相似文献