中华婪步甲共生放线菌的抗菌活性筛选及菌株BJ37的初步鉴定

利用平板分离法从中华婪步甲(Harpalus sinicus)中分离得到56株共生放线菌。其中菌株BJ37具有较好的抗菌活性,其发酵液对枯草芽胞杆菌和白色念珠菌的抑菌圈直径均大于30.0 mm。进一步研究BJ37发酵液不同极性溶剂萃取物的抗菌活性,结果表明在中等极性部位存在活性物质。通过形态学特征和分子生物学分析确定该菌株相似菌株为委内瑞拉链霉菌(Streptomyces venezuelae)。菌株BJ37作为微生物杀菌剂潜在产生菌值得进一步研究。     

A facile synthesis, structure, and antimicrobial evaluation of novel 4-arylhydrazono-5-trifluoromethyl-2,4-dihydropyrazol-3-ones, their N- and N,O-bis-β-d-glucosides

Synthesis of some novel 4-arylhydrazono-5-trifluoromethyl-2,4-dihydropyrazol-3-ones, their N- and N,O-bis- β-d-glucosides is described. Antimicrobial evaluation of eight selected compounds against Aspergillus fumigatus RCMB 002008 (1), Penicillium italicum RCMB 001018 (1), Syncephalastrum racemosum RCMB 016001, Candida albicans RCMB 005003, Staphylococcus aureus RCMB 106-001 (1), Pseudomonas aeruginosa RCMB 102-002, Bacillus subtilis RCMB 101-001, and Escherichia coli RCMB 103-001 has been achieved. The screening results indicated that all the tested compounds exhibited different inhibitory effects against five to seven different organisms of the eight test organisms.     

Isolation and identification of antimicrobial agent-producing bacterium from <Emphasis Type="Italic">Taxus baccata</Emphasis> rhizosphere antagonistic against clinically significant microbes

A bacterium identified as Pseudomonas fluorescence was isolated from Taxus baccata rhizosphere. Ethyl acetate extract from its culture filtrate yielded an active antimicrobial compound that was purified by TLC. The active metabolites were resolved by column chromatography on silica gel (60–120 mesh). The compound was further characterized on the basis of spectral data (UV, IR and ¹HNMR), which indicated the presence of an aromatic ring and phenolic functionality. The compound showed significant antimicrobial activity against two-gram positive bacteria (B. subtilis and S. aureus), four-gram negative bacteria (E. coli, K. pneumoniae, S. flexneri and P. aeruginosa), and one pathogenic fungus (Candida albicans). The minimum inhibitory concentration (MIC) of the compound ranged between 75μg to 250 μg/ml.     

Expression of sfp gene and hydrocarbon degradation by Bacillus subtilis

Bacillus subtilis C9 produces a lipopeptide-type biosurfactant, surfactin, and rapidly degrades alkanes up to a chain length of C₁₉. The nucleotide sequence of the sfp gene cloned from B. subtilis C9 was determined and its deduced amino acid sequence showed 100% homology with the sfp gene reported before [Nakano et al. (1992) Mol. Gen. Genet. 232: 313–321]. To transform a non-surfactin producer, B. subtilis 168, to a surfactin producer, the sfp gene cloned from B. subtilis C9 was expressed in B. subtilis 168. The transformed B. subtilis SB103 derivative of the strain 168 was shown to produce surfactin measured by its decrease in surface tension, emulsification activity, and TLC analysis of the surface active compound isolated from the culture broth. Like B. subtilis C9, B. subtilis SB103 containing sfp gene readily degraded aliphatic hydrocarbons (C_10–19), though its original strain did not. The addition of surfactin (0.5%, w/v) to the culture of B. subtilis 168 significantly stimulated the biodegradation of hydrocarbons of the chain lengths of 10–19; over 98% of the hydrocarbons tested were degraded within 24 h of incubation. These results indicate that the lipopeptide-type biosurfactant, surfactin produced from B. subtilis enhances the bioavailability of hydrophobic hydrocarbons.     

Cell hydrophobicity of <Emphasis Type="Italic">Pseudomonas</Emphasis> spp. and <Emphasis Type="Italic">Bacillus</Emphasis> spp. bacteria and hydrocarbon biodegradation in the presence of Quillaya saponin

Biodegradation and hydrophobicity of Pseudomonas spp. and Bacillus spp. strains were tested at different concentrations of the biosurfactant Quillaya saponin. A model mixture of hydrocarbon (dodecane and hexadecane) was used for estimating the influence of surfactants on biodegradation. The bacterial adhesion to hydrocarbon method for determination of bacterial cell surface hydrophobicity was exploited. Among the tested bacterial strains the higher hydrophobicity was noticed for Pseudomonas aeruginosa TK. The hydrophobicity of this strain was 84%. The highest hydrocarbon biodegradation was observed for P. aeruginosa TK (49%) and Bacillus subtilis (35%) strains after 7 days of experiments. Generally the addition of Quillaya saponin increased hydrocarbon biodegradation remarkably. The optimal concentration proved to be 80 mg l⁻¹. The degree of hydrocarbon biodegradation was 75% for P. aeruginosa TK after the addition of saponin. However the most significant increase in biodegradation after addition of Quillaya saponin was in the case of P. aeruginosa 25 and Pseudomonas putida (the increase of biodegradation from 21 to 52% and from 31 to 66%, respectively). It is worth mentioning that decrease of hydrophobicity is correlated with the best biodegradation by P. aeruginosa strain. For the remaining strains, no significant hydrophobicity changes in relation to the system without surfactant were noticed.     

Selective control of cyanobacteria by surfactin-containing culture broth of Bacillus subtilis C1

Of several types of chemical surfactants and biosurfactants, only the culture broth of Bacillus subtilis C1 containing surfactin at 10 mg l^–1 completely inhibited the growth of Microcystis aeruginosa, a bloom-forming cyanobacterium in highly eutrophic lakes. The broth with 10 mg surfactin l^–1 also removed 85% of the maximally grown M. aeruginosa (chlorophyll-a concentration, 1000 g l^–1) within 2 d, and the removal efficiency was enhanced by Ca²⁺ over 1 mM. The growth of Anabaena affinis, another bloom-forming cyanobacterium, was also inhibited about 70% with surfactin at 10 mg l^–1 broth. However, the effect of the broth was delayed over 3 d in the green algae, Chlorella vulgaris and Scenedesmus sp., and was negligible in a diatom, Navicula sp., indicating the potential for the selective control of cyanobacterial blooms.     

Characterization of a novel biosurfactant producing Pseudomonas koreensis lineage that is endemic to Cuatro Ciénegas Basin

The aim of this work is the taxonomic characterization of three biosurfactant-producing bacterial isolates from the Churince system at Cuatro Ciénegas Basin (CCB) in the Mexican State of Coahuila, and the study of the possible role of biosurfactant production in their ecology and evolution. We determined that these isolates belong to a Pseudomonas koreensis lineage endemic to CCB, using standard taxonomical techniques, phylogenetic analysis of three chromosomal loci and phenotypic characterization. This new lineage has the distinct capacity to produce a biosurfactant when compared with previously reported P. koreensis isolates recovered from agricultural soils in Korea. We present evidence suggesting that the biosurfactant secreted by CCB P. koreensis strains is involved in their ability to compete with a CCB Exiguobacterium aurantiacum strain (m5-66) used as a model organism in competition experiments. Furthermore, the ethyl acetate extract of culture supernatant of CCB P. koreensis strains results in growth inhibition not only of E. aurantiacum m5-66, but also of a Bacillus subtilis type strain (ATCC6633). Based on these results we propose that the production of biosurfactant could be of ecological importance and could play a role in the separation of the P. koreensis CCB lineage.     

Rhamnolipid–Biosurfactant Permeabilizing Effects on Gram-Positive and Gram-Negative Bacterial Strains

The potential of biosurfactant PS to permeabilize bacterial cells of Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis on growing (in vivo) and resting (in vitro) cells was studied. Biosurfactant was shown to have a neutral or detrimental effect on the growth of Gram-positive strains, and this was dependent on the surfactant concentration. The growth of Gram-negative strains was not influenced by the presence of biosurfactant in the media. Cell permeabilization with biosurfactant PS was shown to be more effective with B. subtilis resting cells than with Pseudomonas aeruginosa. Scanning-electron microscopy observations showed that the biosurfactant PS did not exert a disruptive action on resting cells such that it was detrimental to the effect on growing cells of B. subtilis. Low critical micelle concentrations, tender action on nongrowing cells, and neutral effects on the growth of microbial strains at low surfactant concentrations make biosurfactant PS a potential candidate for application in different industrial fields, in environmental bioremediation, and in biomedicine.     

Synthesis,antibacterial and antifungal activities of some carbazole derivatives

A series of N-substituted carbazole derivatives were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Bacillus proteus, Candida albicans and Aspergillus fumigatus by two fold serial dilution technique. Some of the synthesized compounds displayed comparable or even better antibacterial and antifungal activities than reference drugs fluconazole, chloramphenicol and norfloxacin against tested strains.     

Alkaloid profile and antimicrobial activity of <Emphasis Type="Italic">Lupinus angustifolius</Emphasis> L. alkaloid extract

Purpose of the present study was to evaluate alkaloid profile of the aerial parts of Lupinus angustifolius growing in Turkey by capillary gas chromatography-mass spectrometry (GC-MS). Fifteen alkaloids were identified by capillary GC-MS. 13α-Hydroxylupanine (50.78%) and lupanine (23.55%) were determined as the main alkaloids in the aerial parts of L. angustifolius. Ammodendrine, isoangustifoline, tetrahydrorhombifoline, angustifoline, α-isolupanine, 5,6-dehydrolupanine, 11,12-dehydrolupanine, 13α-acetoxylupanine, 13α-isovaleroyloxylupanine, 13α-valeroyloxylupanine, 13α-tigloyloxylupanine, 13α-cis-cinnamoyloxylupanine and 13α-cis-cinnamoyloxy-17-oxolupanine were identified as the minor alkaloids of the plant. Furthermore, antibacterial and antifungal activities of L. angustifolius alkaloid extract were tested against standard strains of the following bacteria; Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus as well as the fungi; Candida albicans and C. krusei. The alkaloid extract showed significant activity on B. subtilis, S. aureus and P. aeruginosa while it was weakly active on E. coli. On the other hand, the extract possessed moderate activity against C. albicans and C. krusei.     

Bacteriocin-like inhibitory substances from <Emphasis Type="Italic">Campylobacter</Emphasis> spp.

Twenty-five Campylobacter isolates were screened for production of antimicrobial substances using a deferred antagonism assay. Sixteen isolates showed activity against either Staphylococcus aureus, Salmonella enterica serovar Enteritidis or Candida albicans. The inhibitory activity was sensitive to treatment with pronase E, trypsin and pepsin, suggesting that the antimicrobial compound(s) are proteinaceous. Activity spectra of isolates included S. aureus, Micrococcus luteus, Streptococcus sp., Bacillus subtilis, a drug-resistant clinical isolate of S. aureus and one isolate of C. albicans. Producing isolates showed cross-immunity and inhibitory activity was only observed on solid media. The findings of this study suggest that Campylobacter produces proteinaceous inhibitory substances.     

The antimicrobial activity of Aspergillus fumigatus is enhanced by a pool of bacteria

In a screening program for new antibiotic producers, a strain of Aspergillus fumigatus was isolated from Brazilian soil samples. A pool of autoclaved bacteria was added to part of the fungus culture on the second day of fermentation to increase antibiotic production. The chloroform extract from the culture broth to which the pool of autoclaved bacteria was added showed an increase of 55%, 63% and more than 100% in activity against Staphylococcus aureus, Candida albicans and Micrococcus luteus, respectively. Also, the HPLC chromatographic profiles of the chloroform extracts from both culture conditions were different. Two active compounds were isolated from the broth of the culture grown in the presence of pooled bacteria and were identified as 3,4-dimethoxyphenol and 1,3,5-trimethoxybenzene.     

On the control of HAB species using low biosurfactant concentrations

Biosurfactants have been suggested as a method to control harmful algal blooms (HABs), but warrant further and more in-depth investigation. Here we have investigated the algicidal effect of a biosurfactant produced by the bacterium Pseudomonas aeruginosa on five diverse marine and freshwater HAB species that have not been tested previously. These include Alexandrium minutum (Dinophycaee), Karenia brevis (Dinophyceae), Pseudonitzschia sp. (Bacillariophyceae), in marine ecosystems, and Gonyostomum semen (Raphidophyceae) and Microcystis aeruginosa (Cyanophyecae) in freshwater. We examined not only lethal but also sub-lethal effects of the biosurfactant. In addition, the effect of the biosurfactant on Daphnia was tested. Our conclusions were that very low biosurfactant concentrations (5 μg mL⁻¹) decreased both the photosynthesis efficiency and the cell viability and that higher concentrations (50 μg mL⁻¹) had lethal effects in four of the five HAB species tested. The low concentrations employed in this study and the diversity of HAB genera tested suggest that biosurfactants may be used to either control initial algal blooms without causing negative side effect to the ecosystem, or to provoke lethal effects when necessary.     

Production of bacteriolytic enzymes by mycoparasitic Trichoderma strains

Eighteen mycoparasitic Trichoderma strains were tested for their ability to degrade heat-inactivated Bacillus cereus var. mycoides, B. megaterium, B. subtilis, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa and Serratia marcescens cells. The non-inductive and inductive ferment broths of five strains with good degrading abilities towards B. subtilis were investigated for specific degrading enzyme activities. In addition to trypsin- and chymotrypsin-like protease activities, -1,4-N-acetyl-glucosaminidase (NAGase) was also secreted. Strain Trichoderma harzianum T19 had the most outstanding degrading abilities. The extracellular degrading enzymes of this strain were separated on a Sephadex G-150 column, and their preliminary characterization was performed. The results demonstrated that muramidase-like activities are present in the ferment broth of this T. harzianum strain.     

Adsorption of dirhamnolipid on four microorganisms and the effect on cell surface hydrophobicity

In this study, adsorption of dirhamnolipid biosurfactant on a Gram-negative Pseudomonas aeruginosa, two Gram-positive Bacillus subtilis, and a yeast, Candida lipolytica, was investigated, and the causality between the adsorption and change of cell surface hydrophobicity was discussed. The adsorption was not only specific to the microorganisms but also depended on the physiological status of the cells. Components of the biosurfactant with different rhamnosyl number or aliphatic chain length also exhibited slight difference in adsorption manner. The adsorption indeed caused the cell surface hydrophobicity to change regularly; however, the changes depended on both the concentrations of rhamnolipid solutions applied and the adsorbent physiological conditions. Orientation of rhamnolipid monomers on cell surface and micelle deposition are supposed to be the basic means of adsorption to change cell hydrophobicity at low and high rhamnolipid concentrations, respectively. This study proposed the possibility to modify cell surface hydrophobicity with biosurfactant of low concentrations, which may be of importance in in situ soil remediation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Enhancement of stability of biosurfactant produced by <Emphasis Type="Italic">Candida lipolytica</Emphasis> using industrial residue as substrate

This work describes experimental results carried out on the fermentation of Candida lipolytica, which produced a new biosurfactant when grown on a vegetable oil refinery residue as substrate. The cell-free culture broth containing the biosurfactant formed stable emulsions with hydrophobic natural compounds. Emulsification properties of the biosurfactant were not affected by salinity; however, treatment at a higher temperature decreased the emulsification activity, indicating applications in oil recovery. The isolated biosurfactant corresponds to a yield of 4.5 g/l, and the surface tension of water was reduced from 71 to 32 mN/m. Preliminary chemical characterizations showed that the biosurfactant consisted of protein (50%), lipid (20%), and carbohydrate (8%).     

Pseudomonas aeruginosa, Candida albicans, and device-related nosocomial infections: implications, trends, and potential approaches for control

For many years, device-associated infections and particularly device-associated nosocomial infections have been of considerable concern. Recently, this concern was heightened as a result of increased antibiotic resistance among the common causal agents of nosocomial infections, the appearance of new strains which are intrinsically resistant to the antibiotics of choice, and the emerging understanding of the role biofilms may play in device-associated infections and the development of increased antibiotic resistance. Pseudomonas aeruginosa and Candida albicans are consistently identified as some of the more important agents of nosocomial infections. In light of the recent information regarding device-associated nosocomial infections, understanding the nature of P. aeruginosa and C. albicans infections is increasingly important. These two microorganisms demonstrate: (1) an ability to form biofilms on the majority of devices employed currently, (2) increased resistance/tolerance to antibiotics when associated with biofilms, (3) documented infections noted for virtually all indwelling devices, (4) opportunistic pathogenicity, and (5) persistence in the hospital environment. To these five demonstrated characteristics, two additional areas of interest are emerging: (a) the as yet unclear relationship of these two microorganisms to those species of highly resistant Pseudomonas spp and Candida spp that are of increasing concern with device-related infections, and (b) the recent research showing the dynamic interaction of P. aeruginosa and C. albicans in patients with cystic fibrosis. An understanding of these two opportunistic pathogens in the context of their ecosystems/biofilms also has significant potential for the development of novel and effective approaches for the control and treatment of device-associated infections.     

椿根皮的化学成分及抑菌活性研究

为探寻椿根皮抑菌的物质基础，该研究采用硅胶、Sephadex LH-20等方法对椿根皮甲醇提取物进行分离和纯化，通过理化性质和波谱数据分析单体化合物的结构，并以卡那霉素为对照组采用流式细胞法测试化合物的抑菌活性。结果表明：从椿根皮中得到22个化合物，分别鉴定为pleuchiol (1)、withastramonolide (2)、7-ketositosterol (3)、白桦酯醇(4)、桦木酸甲酯(5)、1, 2, 4-trimethoxybenzene (6)、顺丁烯二酸二甲酯(7)、sonderianol (8)、dibutyl phthalate (9)、pinoresinol (10)、对羟基苯甲酸乙酯(11)、avenalumic acid methyl ester (12)、5,3′-dihydroxy-3,7,4′-trimethoxy-flavone (13)、spathulenol (14)、2-甲基-5-丙基酮-7-羟基色原酮(15)、 7,4′-dihydroxyflavone (16)、annphenone (17)、3-羟基-4-甲氧基苯甲酸(18)、5,3′...     

Antimicrobial metal-based thiophene derived compounds

A novel series of thiophene derived Schiff bases and their transition metal- [Co(II), Cu(II), Zn(II), Ni(II)] based compounds are reported. The Schiff bases act as tridentate ligands toward metal ions via azomethine-N, deprotonated-N of ammine substituents and S-atom of thienyl moiety. The synthesized ligands along with their metal complexes were screened for their in vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and for antifungal activity against six fungal pathogens (Trichophytonlongifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata). The results of antimicrobial studies revealed the free ligands to possess potential activity which significantly increased upon chelation.     

Effect of biodelignification of rice straw on humification and humus quality by Phanerochaete chrysosporium and Streptomyces badius

The effect of biodelignification of rice straw by two different ligninolytic organisms, Phanerochaete chrysosporium (white-rot fungus) and Streptomyces badius (actinomycetes), on humus quality was investigated during a 56-day incubation at 30 °C. Lignin degradation, the release of humic extract (HE), humic acid (HA) and fulvic acid (FA), E4/E6 ratio of HA, and humification index (HI, HA/FA) were measured during the incubation. Lignin was degraded by both organisms, but to different extents. Lignin was degraded to 41% and 31% by P. chrysosporium and S. badius, respectively. HE released by P. chrysosporium and S. badius were, respectively, 2.10 and 2.13 times larger than that in the control at the maximum values. A significant correlation between lignin degradation and humus-related parameters involving HA fraction showed that both organisms are converting lignin to humic substances.