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1.
This study demonstrated the potential of microbial isolates from Antarctic soils to produce hydrolytic enzymes by using specific substrates. The results revealed potential of the strains to produce a broad spectrum of hydrolytic enzymes. Strain A-1 isolated from soil samples in Casey Station, Wilkes Land, was identified as Nocardioides sp. on the basis of morphological, biochemical, physiological observations and also chemotaxonomy analysis. Enzymatic and antimicrobial activities of the cell-free supernatants were explored after growth of strain A-1 in mineral salts medium supplemented with different carbon sources. It was found that the carbon sources favored the production of a broad spectrum of enzymes as well as compounds with antimicrobial activity against Gram-positive and Gram-negative bacteria, especially Staphylococcus aureus and Xanthomonas oryzae. Preliminary analysis showed that the compounds with antimicrobial activity produced by the strain A-1 are mainly glycolipids and/or lipopeptides depending on the used carbon source. The results revealed a great potential of the Antarctic Nocardioides sp. strain A-1 for biotechnological, biopharmaceutical and biocontrol applications as a source of industrially important enzymes and antimicrobial/antifungal compounds.  相似文献   

2.
Bacteriophages isolated from culture supernatants of Pseudomonas syringae pv. syringae and from sewage were identified. The DNA from each phage was isolated and digested with the restriction endonuclease EcoRI. Eight isolates were determined to be different, with two phage isolates from sewage having restriction patterns identical to two phages from culture supernatants. The sizes of the phage DNA ranged from 24 to49 kilobases for isolates from sewage and from 39 to 52.5 kilobases for the isolates from culture supernatants. Buoyant densities of phage particles in CsCl varied from 1.498 to 1.507 g/cm3 for isolates from sewage and from 1.506 to 1.516 g/cm3 for isolates from culture supernatants. Electron microscopy revealed four morphological types. Based on plaque-forming ability of culture supernatants, 31 out of 47 strains of P. syringae are probably lysogenic.  相似文献   

3.

Background and Aims

Several strains of rhizobacteria may be found in the rhizospheric soil, on the root surface or in association with rice plants. These bacteria are able to colonize plant root systems and promote plant growth and crop yield through a variety of mechanisms. The objectives of this study were to isolate, identify, and characterize putative plant growth-promoting rhizobacteria (PGPR) associated with rice cropped in different areas of southern Brazil.

Methods

Bacterial strains were selectively isolated based on their growth on three selective semi-solid nitrogen-free media. Bacteria were identified at the genus level by PCR-RFLP 16S rRNA gene analysis and partial sequencing methodologies. Bacterial isolates were evaluated for their ability to produce indolic compounds and siderophores and to solubilize phosphate. In vitro biological nitrogen fixation and the ability to produce 1-aminocyclopropane-1-carboxylate deaminase were evaluated for each bacterial isolate used in the inoculation experiments.

Results

In total, 336 bacterial strains were isolated representing 31 different bacterial genera. Strains belonging to the genera Agrobacterium, Burkholderia, Enterobacter, and Pseudomonas were the most prominent isolates. Siderophore and indolic compounds producers were widely found among isolates, but 101 isolates were able to solubilize phosphate. Under gnotobiotic conditions, eight isolates were able to stimulate the growth of rice plants. Five of these eight isolates were also field tested in rice plants subjected to different nitrogen fertilization rates.

Conclusions

The results showed that the condition of half-fertilization plus separate inoculation with the isolates AC32 (Herbaspirillum sp.), AG15 (Burkholderia sp.), CA21 (Pseudacidovorax sp.), and UR51 (Azospirillum sp.) achieved rice growth similar to those achieved by full-fertilization without inoculation, thus highlighting the potential of these strains for formulating new bioinoculants for rice crops.  相似文献   

4.
Emergence of multidrug resistant bacteria has made the search for novel bioactive compounds from natural and unexplored habitats a necessity. Actinobacteria have important bioactive substances. The present study investigated antimicrobial activity of Actinobacteria isolated from soil samples of Egypt. One hundred samples were collected from agricultural farming soil of different governorates. Twelve isolates have produced activity against the tested microorganisms (S. aureus, Bacillus cereus, E. coli, K. pneumoniae, P. aeruginosa, S. Typhi, C. albicans, A. niger and A. flavus). By VITEK 2 system version: 07.01 the 12 isolates were identified as Kocuria kristinae, Kocuria rosea, Streptomyces griseus, Streptomyces flaveolus and Actinobacteria. Using ethyl acetate extraction method the isolates culture’s supernatants were tested by diffusion method against indicator microorganisms. These results indicate that Actinobacteria isolated from Egypt farms could be sources of antimicrobial bioactive substances.  相似文献   

5.
Several fungal species were isolated from different sources: post-harvest sugarcane residue, soil, decomposing forest litter and from mycelia obtained from the inner parts of fresh fungal fruiting bodies collected in Las Yungas region (Argentina). These isolates were first screened for their ability to produce carboxymethyl cellulose (CMC) degradation and guaiacol oxidation. After primary screening, seventeen isolates were further tested for their ligninolytic ability by assessing polyphenoloxidase, laccase, manganese peroxidase and endoxylanase activities. Based on their lignocellulolytic activities, five isolates (named Bjerkandera sp. Y-HHM2, Phanerochaete sp. Y-RN1, Pleurotus sp. Y-RN3, Hypocrea nigricans SCT-4.4 and Myrothecium sp. S-3.20) were selected for liquid and solid-state fermentation assays in culture media including sugarcane debris. Lignocellulolytic enzymes production, dry mass loss and phenol concentration in the water soluble fraction were then evaluated. Results suggest that native strains with lignocellulolytic activity are suitable to increase post-harvest sugarcane residue decomposition and support the use of these strains as an alternative to pre and post-harvest burning. Biological treatments using Phanerochaete sp. Y-RN1, Pleurotus sp. Y-RN3 and Myrothecium sp. S-3.20 could be used to degrade and increase the accessibility to lignocellulose components of sugarcane residue.  相似文献   

6.
An attempt to restore the settling ability of denatured bulking sludge was under-taken by changing the microflora in waste treatment tanks. A cell suspension of mixed cultures of ten strains of bacteria, which were isolated from normal activated sludge from night soil plants, and a type culture Zoogloea ramigera IAM1236 was seeded into a laboratory-scale aeration tank containing bulking sludge collected from municipal night soil or a food processing (bean curd production) waste treatment plant. The tank was fed with synthetic wastewater or industrial waste and aerated for 22 days. After 5 days, the microflora in the sludge changed remarkably with the seeding of the bacterial culture; filamentous organisms disappeared and active protozoa (Vorticella sp., Epistylis sp., and Lecane sp.) appeared. The sludge became compact and settled rapidly. The SV30 of the sludge temporarily increased, but in the end decreased from 97 to 20%. The CODcr value decreased from 300 to 20 ppm. In the tank without seeding, the sludge contained almost filamentous organisms only which floated and finally decomposed. The effects were confirmed by applied tests in 700-ton scale and 100-ton scale aeration tanks of municipal night soil and a food processing waste treatment plant, respectively.  相似文献   

7.
A total of 40 endophytic bacterial isolates obtained from banana tree roots were characterized for their biotechnological potential for promoting banana tree growth. All isolates had at least one positive feature. Twenty isolates were likely diazotrophs and formed pellicles in nitrogen-free culture medium, and 67% of these isolates belonged to the genus Bacillus sp. The isolates EB-04, EB-169, EB-64, and EB-144 had N fixation abilities as measured by the Kjeldahl method and by an acetylene reduction activity assay. Among the 40 isolates, 37.5% were capable of solubilizing inorganic phosphate and the isolates EB-47 and EB-64 showed the highest solubilization capacity. The isolate EB-53 (Lysinibacillus sp.) had a high solubilization index, whereas 73% of the isolates had low solubilization indices. The synthesis of indole-3-acetic acid (IAA) in the presence of L-tryptophan was detected in 40% of the isolates. The isolate EB-40 (Bacillus sp.) produced the highest amount of IAA (47.88 μg/ml) in medium supplemented with L-tryptophan and was able to synthesize IAA in the absence of L-tryptophan. The isolates EB-126 (Bacillus subtilis) and EB-47 (Bacillus sp.) were able to simultaneously fix nitrogen, solubilize phosphate and produce IAA in vitro. The results of this study demonstrated that the isolates analyzed here had diverse abilities and all have the potential to be used as growth-promoting microbial inoculants for banana trees.  相似文献   

8.
Fungal and bacterial pathogens infect a diverse range of hosts including various plant and animal species. Fungal and bacterial diseases, especially of plants and aquatic animals, such as fish, lead to significant damage to crops and aquaculture, respectively, worldwide. The present study was conducted to isolate and characterize potent Bacillus strains with significant antagonistic activity against the major plant and fish pathogenic fungi and bacteria. We randomly collected 22 isolates of Bacillus from the soil, rhizosphere, and sediment from different parts of Bangladesh. Initial characterization, based on in vitro antagonistic activity on the culture plate, resulted in the selection of four gram-positive Bacillus sp. isolates. Among these, the isolate BC01, obtained from soil demonstrated the highest broad-spectrum anti-bacterial and anti-fungal activities. We confirmed the genus of BC01 to be Bacillus by morphological and biochemical tests as well as using molecular data analysis tools, including the study of 16s rDNA, phylogenetic relationship, and evolutionary divergence scores. The isolate significantly inhibited the mycelial growth of the plant pathogen, Penicillium digitatum and fish pathogen, Aphanomyces invadans in vitro. The anti-bacterial effect of the isolate was also evaluated against Pseudomonas spp. and Xanthomonas spp., the two deadliest plant pathogens, and Aeromonas veronii, Pseudomonas fluorescens, and Streptococcus iniae, three major fish pathogens that are primarily responsible for global aquaculture loss. The results of the present study could pave the way for developing potent drugs to combat microbial infection of plants and fish.  相似文献   

9.
Thaxtomin A is the main phytotoxin produced by Streptomyces scabies, a causal agent of potato scab. Thaxtomin A is a yellow compound composed of 4-nitroindol-3-yl-containing 2,5-dioxopiperazine. A collection of nonpathogenic streptomycetes isolated from potato tubers and microorganisms recovered from a thaxtomin A solution were examined for the ability to grow in the presence of thaxtomin A as a sole carbon or nitrogen source. Three bacterial isolates and two fungal isolates grew in thaxtomin A-containing media. Growth of these organisms resulted in decreases in the optical densities at 400 nm of culture supernatants and in 10% reductions in the thaxtomin A concentration. The fungal isolates were identified as a Penicillium sp. isolate and a Trichoderma sp. isolate. One bacterial isolate was associated with the species Ralstonia pickettii, and the two other bacterial isolates were identified as Streptomyces sp. strains. The sequences of the 16S rRNA genes were determined in order to compare thaxtomin A-utilizing actinomycetes to the pathogenic organism S. scabies and other Streptomyces species. The nucleotide sequences of the γ variable regions of the 16S ribosomal DNA of both thaxtomin A-utilizing actinomycetes were identical to the sequence of Streptomyces mirabilis ATCC 27447. When inoculated onto potato tubers, the three thaxtomin A-utilizing bacteria protected growing plants against common scab, but the fungal isolates did not have any protective effect.  相似文献   

10.
This study evaluated the probiotic potential of GP21 (Pseudomonas sp.) and GP12 (Psychrobacter sp.), two bacteria isolated from the intestinal tract of a cold-water fish, Atlantic cod. The antagonistic activity of the two intestinal bacteria against two fish pathogens (Vibrio anguillarum and Aeromonas salmonicida subsp. salmonicida) was studied under different physical conditions. Further, their resistance to physiological barriers and their ability to form biofilms were examined. In addition, a test was conducted to confirm that the isolates were not pathogenic to the host fish. The two bacteria exhibited differences in their antagonism to the pathogens. Both were active against V. anguillarum at mildly acidic conditions over a 5-day period. The activity of GP21 against A. salmonicida was greater at pH 7–8. The maximum antagonistic activity was observed at a temperature of 15°C and at a salt concentration of 15 ppt for both the isolates. They did not produce acids, could release siderophores and tolerated both the acidic environment and the bile salts. Their ability to form biofilms was high around 15°C and when iron was supplemented in the medium at 5 μmol l?1. There was no mortality of fish during the pathogenicity experiment, confirming the safety of both isolates for further applications. Considering the favorable characteristics identified here, it could be concluded that GP21 and GP12 isolated from the gastrointestinal tract of Atlantic cod are potential probiotic candidates.  相似文献   

11.
Biodegradation of the Nitramine Explosive CL-20   总被引:5,自引:2,他引:3       下载免费PDF全文
The cyclic nitramine explosive CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) was examined in soil microcosms to determine whether it is biodegradable. CL-20 was incubated with a variety of soils. The explosive disappeared in all microcosms except the controls in which microbial activity had been inhibited. CL-20 was degraded most rapidly in garden soil. After 2 days of incubation, about 80% of the initial CL-20 had disappeared. A CL-20-degrading bacterial strain, Agrobacterium sp. strain JS71, was isolated from enrichment cultures containing garden soil as an inoculum, succinate as a carbon source, and CL-20 as a nitrogen source. Growth experiments revealed that strain JS71 used 3 mol of nitrogen per mol of CL-20.  相似文献   

12.
The aim of the present study was to ascertain the potency of anti-listerial bacteriocin produced by lactic acid bacteria (LAB) isolated from indigenous samples of dahi, dried fish, and salt-fermented cucumber. A total of 231 LAB isolates were obtained from the samples, of which 51 isolates displayed anti-listerial activity. The anti-listerial LAB were identified by PCR as Lactobacillus sp., Pediococcus sp., Enterococcus sp., and Lactococcus sp. PCR also enabled the detection of Class IIa bacteriocin-encoding genes such as enterocin A, pediocin, and plantaricin A in some of the LAB isolates. The culture filtrate from anti-listerial LAB isolates demonstrated bacteriocin-like inhibitory substance (BLIS) against common Gram-positive pathogenic bacteria such as Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus, and partial characterization of BLIS confirmed the production of bacteriocin by the LAB isolates. Sensitive fluorescence-based assays employing specific probes indicated the comparative potencies of the bacteriocin and clearly revealed the membrane-targeted anti-listerial activity of the purified bacteriocin produced by selected LAB isolates. The food application potential of plantaricin A produced by a native isolate Lactobacillus plantarum CRA52 was evidenced as the bacteriocin suppressed the growth of Listeria monocytogenes Scott A inoculated in paneer samples that were stored at 8?°C for 5?days.  相似文献   

13.
AIMS: To determine the microbial succession of the dominating taxa and functional groups of microorganisms and the total microbial activity during the composting of biowaste in a monitored process. METHODS AND RESULTS: Biowaste (vegetable, fruit and garden waste) was composted in a monitored composting bin system. During the process, taxonomic and functional subpopulations of microorganisms were enumerated, and dominating colonies were isolated and identified. All counts decreased during the thermophilic phase of the composting, but increased again when the temperature declined. Total microbial activity, measured with an enzyme activity assay, decreased during the thermophilic phase, increased substantially thereafter, and decreased again during maturation. Bacteria dominated during the thermophilic phase while fungi, streptomycetes and yeasts were below the detection limit. Different bacterial populations were found in the thermophilic and mesophilic phases. In fresh wastes and during the peak-heating phase, all bacterial isolates were bacilli. During the cooling and maturation phase the bacterial diversity increased, including also other Gram-positive and Gram-negative bacteria. Among the fungi, Aspergillus spp. and Mucor spp. were predominant after the thermophilic phase. CONCLUSIONS: The microbial abundance, composition and activity changed substantially during composting and compost maturity was correlated with high microbial diversity and low activity. SIGNIFICANCE AND IMPACT OF THE STUDY: A more complete overview of the whole composting process of biowaste, based on microbial counts, species diversity and functional groups and abiotic parameters is presented, and the potential of a simple enzyme assay to measure total microbial activity was demonstrated.  相似文献   

14.
Abstract

Lake Tuz, the largest hypersaline lake in Turkey, has a great variety of microbial communities that adapted to its extreme environment and produce many industrially important compounds such as photosensitive bacteriorhodopsins. So far, the information about the bacteriorhodopsin-producing haloarchaea species of the lake is still limited. In the present study, archaeal bacteriorhodopsin producers were isolated from three locations of the lake. Their bacteriorhodopsin-producing capability was validated by the purification and SDS-PAGE analysis of the delipidated bacteriorhodopsin molecule. The active isolates were identified by the sequencing of partial 16S rDNA gene regions. According to the results, 11 bacteriorhodopsin-producing isolates grouped in Halobacterium salinarum (4), Halobacterium sp. (3), Haloarcula salaria (2), Haloarcula sp. (1) and Halorubrum sp. (1). Our research demonstrated that Lake Tuz is an important natural source of bacteriorhodopsin-producing haloarchaea and the isolates can be valuable for the related technological applications.  相似文献   

15.
Bacteria degrading a very long-chain alkane, n-tetracosane, were isolated from enrichment culture of soil in Okinawa. Phylogenetic analysis of their16S rRNA sequences revealed that they belong to classes Gammaproteobacteria and Actinomycetes. Three isolates belonging to the genera Acinetobacter sp., Pseudomonas sp., and Gordonia sp. showed a stable growth on n-tetracosane and had a wide range of assimilation of aliphatic hydrocarbons from C12 to C30, while not on alkanes shorter than C8. Of the isolates, Gordonia sp. degraded oil tank sludge hydrocarbons efficiently by solving the sludge in a hydrophobic solvent, while Acinetobacter sp. showed little degradation, possibly due to the difference in the mechanism of hydrophobic substrate incorporation between proteobacteria and actinobacteria. The data suggested that non-heme di-iron monooxygenases of the AlkB-type, not bacterial CYP153 type cytochrome P450 alkane hydroxylase, was involved in the alkane degradation.  相似文献   

16.
A total of 445 actinomycete isolates were obtained from 16 medicinal plant rhizosphere soils. Morphological and chemotaxonomic studies indicated that 89% of the isolates belonged to the genus Streptomyces, 11% were non-Streptomycetes: Actinomadura sp., Microbispora sp., Micromonospora sp., Nocardia sp, Nonomurea sp. and three isolates were unclassified. The highest number and diversity of actinomycetes were isolated from Curcuma mangga rhizosphere soil. Twenty-three Streptomyces isolates showed activity against at least one of the five phytopathogenic fungi: Alternaria brassicicola, Collectotrichum gloeosporioides, Fusarium oxysporum, Penicillium digitatum and Sclerotium rolfsii. Thirty-six actinomycete isolates showed abilities to produce indole-3-acetic acid (IAA) and 75 isolates produced siderophores on chrome azurol S (CAS) agar. Streptomyces CMU-PA101 and Streptomyces CMU-SK126 had high ability to produced antifungal compounds, IAA and siderophores.  相似文献   

17.
Marine sponges and other sessile macro-organisms were collected at a shallow water hydrothermal site in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the hydrothermal vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður hydrothermal vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research.  相似文献   

18.
Bacillus sp. P45, isolated from the intestine of the Amazon basin fish Piaractus mesopotamicus, showed proteolytic activity when grown on skimmed milk and feather meal agar plates. The keratinolytic potential of this strain was evaluated on whole feather broth and human hair broth. Bacillus sp. P45 degraded almost 90% of chicken feathers after 72 h of submerged cultivation on whole feather broth, and the production of extracellular proteases was observed. The formation of thiol groups was also detected during growth, indicating the contribution of sulphitolysis to the efficient hydrolysis of feather keratin. Nevertheless, Bacillus sp. P45 was unable to degrade hair keratin, possibly due to the conformational diversity of this substrate in comparison to feather keratin. Additionally, preliminary results demonstrated that this strain might be utilized in the degradation of recalcitrant collagen-containing wastes. The keratinolytic character of Bacillus sp. P45 might be utilized in environmental-friendly processes such as bioconversion of waste feathers, representing an alternative way of waste management that could lead to the production of value-added products such as microbial biomass, protein hydrolysates and proteolytic enzymes.  相似文献   

19.
Corky root disease of tomato caused by Pyrenochaeta lycopersici is an economically important disease in organic tomato production. This study aimed to evaluate the effects of various composts consisting of green manure, garden waste and horse manure against corky root disease through bioassay under greenhouse conditions, where soil naturally infested with P. lycopersici was used as a root substrate. The various composts were mixed at a rate of 20% (v/v) with the infested soil. Disease severity (measured as infected roots) in the unamended soil was compared with that in the soil–compost mixtures. One of the composts made from garden waste significantly reduced the disease, whereas horse manure compost significantly stimulated it. Lower concentrations of NH4‐N and total carbon and a higher concentration of Ca in the substrate were correlated with lower level of corky root disease. Addition of green manure or garden waste compost to the infested soil increased total microbial activity or population density of copiotrophic bacteria and actinomycetes, respectively. However, increased microbial activity or microbial population in soil–compost mixtures was not associated with a reduction in corky root disease severity in the present study.  相似文献   

20.
Approximately 100 million tons of anhydrosugars, such as levoglucosan and cellobiosan, are produced through biomass burning every year. These sugars are also produced through fast pyrolysis, the controlled thermal depolymerization of biomass. While the microbial pathways associated with levoglucosan utilization have been characterized, there is little known about cellobiosan utilization. Here we describe the isolation and characterization of six cellobiosan-utilizing microbes from soil samples. Each of these organisms is capable of using both cellobiosan and levoglucosan as sole carbon source, though both minimal and rich media cellobiosan supported significantly higher biomass production than levoglucosan. Ribosomal sequencing was used to identify the closest reported match for these organisms: Sphingobacterium multivorum, Acinetobacter oleivorans JC3-1, Enterobacter sp SJZ-6, and Microbacterium sps FXJ8.207 and 203 and a fungal species Cryptococcus sp. The commercially-acquired Enterobacter cloacae DSM 16657 showed growth on levoglucosan and cellobiosan, supporting our isolate identification. Analysis of an existing database of 16S rRNA amplicons from Iowa soil samples confirmed the representation of our five bacterial isolates and four previously-reported levoglucosan-utilizing bacterial isolates in other soil samples and provided insight into their population distributions. Phylogenetic analysis of the 16S rRNA and 18S rRNA of strains previously reported to utilize levoglucosan and our newfound isolates showed that the organisms isolated in this study are distinct from previously described anhydrosugar-utilizing microbial species.  相似文献   

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