Showing papers on "Antifungal antibiotic published in 2015"

Identification of a small molecule signaling factor that regulates the biosynthesis of the antifungal polycyclic tetramate macrolactam HSAF in Lysobacter enzymogenes

Abstract: Lysobacter species are emerging as new sources of antibiotics. The regulation of these antibiotics is not well understood. Here, we identified a small molecule metabolite (LeDSF3) that regulates the biosynthesis of the antifungal antibiotic heat-stable antifungal factor (HSAF), a polycyclic tetramate macrolactam with a structure and mode of action distinct from the existing antifungal drugs. LeDSF3 was isolated from the culture broth of Lysobacter enzymogenes, and its chemical structure was established by NMR and MS. The purified compound induced green fluorescence in a reporter strain of Xanthomonas campestris, which contained a gfp gene under the control of a diffusible signaling factor (DSF)-inducible promoter. Exogenous addition of LeDSF3 in L. enzymogenes cultures significantly increased the HSAF yield, the transcription of HSAF biosynthetic genes, and the antifungal activity of the organism. The LeDSF3-regulated HSAF production is dependent on the two-component regulatory system RpfC/RpfG. Moreover, LeDSF3 upregulated the expression of the global regulator cAMP receptor-like protein (Clp). The disruption of clp led to no HSAF production. Together, the results show that LeDSF3 is a fatty acid-derived, diffusible signaling factor positively regulating HSAF biosynthesis and that the signaling is mediated by the RfpC/RpfG-Clp pathway. These findings may facilitate the antibiotic production through applied genetics and molecular biotechnology in Lysobacter, a group of ubiquitous yet underexplored microorganisms.

Chemical composition, antimicrobial and antifungal activities of essential oils of the leaves of Aegle marmelos (L.) Correa growing in Egypt

Abstract: The essential oil obtained by hydrodistillation of Aegle marmelos (L.)Correa leaves were analyzed by GC/MS yield (0.9% v/w). Twenty seven components were identified representing 97.76 % of the total oil composition. The major components were α-phellenderene (20.97%), α-pinene (17.76%) and δ-carene (16.37%) and other abundant components as γ-cadinene (8.01%), trans-2-hydroxycinnmic acid (6.85%) and β-myrcene (4.32%). The essential oil exhibited significant antibacterial activity against Gram-positive bacteria as Streptococcus faecalis with inhibition zone (30 mm) and Gram-negative bacteria as Pseudomonas aeruginosa (28 mm). Moreover, moderate activity was observed against Bacillus subtilis (23 mm), Staphylococcus aureus (23 mm), Sarcina lutea (20 mm), Arthrobacter citreus (20 mm) and Escherichia coli (25 mm) in comparison with antibiotics. The antifungal activity against Aspergillus niger (30 mm) and Candida albicans (30 mm) was higher than the antifungal antibiotics. Moreover, the oil inhibited the germination of Aspergillus niger and Fusarium oxysporum spores at different concentrations.

PilG is Involved in the Regulation of Twitching Motility and Antifungal Antibiotic Biosynthesis in the Biological Control Agent Lysobacter enzymogenes.

Abstract: Lysobacter enzymogenes strain C3 is a gliding bacterium which produces the antifungal secondary metabolite heat-stable antifungal factor (HSAF) and type IV pilus (T4P) as important mechanisms in biological control activity against fungal pathogens. To date, the regulators that control HSAF biosynthesis and T4P-dependent twitching motility in L. enzymogenes are poorly explored. In the present study, we addressed the role of pilG in the regulation of these two traits in L. enzymogenes. PilG of L. enzymogenes was found to be a response regulator, commonly known as a component of a two-component transduction system. Mutation of pilG in strain C3 abolished its ability to display spreading colony phenotype and cell movement at the colony margin, which is indicative of twitching motility; hence, PilG positively regulates twitching motility in L. enzymogenes. Mutation of pilG also enhanced HSAF production and the transcription of its key biosynthetic gene hsaf pks/nrps, suggesting that PilG plays a negative regulatory role in HSAF biosynthesis. This finding represents the first demonstration of the regulator PilG having a role in secondary metabolite biosynthesis in bacteria. Collectively, our results suggest that key ecological functions (HSAF production and twitching motility) in L. enzymogenes strain C3 are regulated in opposite directions by the same regulatory protein, PilG.

Role of transcription factor NimR (YeaM) in sensitivity control of Escherichia coli to 2-nitroimidazole

Abstract: The binding site(s) on the Escherichia coli genome was determined for an uncharacterized AraC/XylS superfamily transcription factor YeaM by using the in vitro genomic SELEX screening system. The only one clear binding target of YeaM was found to locate in the spacer between the divergently transcribed yeaM and yeaN genes. After the phenotype microarray analysis, the major facilitator superfamily transporter YeaN was found to confer E. coli the resistance to 2-nitroimidazole, the antibacterial and antifungal antibiotic, suggesting that YeaN plays a role in 2-nitromidazole efflux. Purified YeaM bound to three sites within this yeaM-yeaN spacer region. Several lines of in vitro and in vivo evidence indicate that YeaM regulates transcription of both the yeaM gene itself and the yeaNO operon. Taken together we propose to rename yeaN to nimT (nitroimidazole transporter) and yeaM to nimR (regulator of nimT).

Engineered biosynthesis of pimaricin derivatives with improved antifungal activity and reduced cytotoxicity

Abstract: Pimaricin is an important antifungal antibiotic for antifungal therapy and prevention of mould contamination in the food industry. In this study, three new pimaricin derivatives, 12-decarboxy-12-methyl pimaricin (1), 4,5-desepoxy-12-decarboxy-12-methyl pimaricin (2), and 2-hydro-3-hydroxy-4,5-desepoxy-12-decarboxy-12-methyl pimaricin (3), were generated through the inactivation of P450 monooxygenase gene scnG in Streptomyces chattanoogensis L10. Compared with pimaricin, 1 displayed a twofold increase in antifungal activity against Candida albicans ATCC 14053 and a 4.5-fold decrease in cytotoxicity with erythrocytes, and 2 had comparable antifungal activity and reduced cytotoxicity, whereas 3 showed nearly no antifungal and hemolytic activities. Genetic and biochemical analyses proved that 1 is converted from 2 by P450 monooxygenase ScnD. Therefore, the overexpression of scnD in scnG-null strain eliminated the accumulation of 2 and improved the yield of 1 by 20 %. Conversely, scnG/scnD double mutation abolished the production of 1 and improved the yield of 2 to 2.3-fold. These results indicate that the pimaricin derivatives with improved pharmacological properties obtained by genetic engineering can be further developed into antifungal agents for potential clinical application.

Genome Sequence of Fungal Species No.11243, Which Produces the Antifungal Antibiotic FR901469.

Abstract: Fungal species No.11243 was originally isolated from a decayed leaf sample collected in Kyoto, Japan. It produces FR901469, a 1,3-beta-glucan synthase inhibitor. The genome sequence of No.11243 was determined and annotated to obtain useful information for improving productivity of the effective antifungal agent FR901469.

Production of Antibiotics

Abstract: Antibiotics are classified based on their mechanism of action in a host. Some of them are bactericides (an agent that destroys bacteria) whereas others are bacteriostatic, meaning they may inhibit the growth of organisms and multiplication of bacteria but do not kill them. They act by interfering with the synthesis of folic acid inside the cell anabolism. Another method of classifying antibiotics is based on mode of action as antibiotics interact with an antigen. This chapter covers the fermentation process, which leads to the synthesis of antibiotics. Penicillin G is made by a fungus, Penicillium chrysogenum. The number of antibiotics from fungal sources is few, although they do include penicillin G and V, and cephalosporin C. These three antibiotics are the major starting materials for the semisynthetic β-lactam antibiotics. The systemic antifungal antibiotic griseofulvin is also of fungal origin. Most antibiotics are produced by fermentation using fungi, including streptomycin and the tetracycline family, among numerous others.

Identification of antifungal antibiotics genes of Bacillus species isolated from different microhabitats using polymerase chain reaction

Abstract: Although many Bacillus species are known to be good antibiotic producers capable of acting as biocontrol agents, the underlying antimicrobial mechanisms are often poorly understood. In this study, 3 Bacillus strains out of 30, demonstrating over 55% mycelial inhibition against Mycosphaerella musicola as well as significant control in plate assays, were examined for the presence of antibiotic biosynthetic genes. The use of 16S rRNA revealed that the three strains belonged to Bacillus amyloliquefaciens (BB30), Bacillus atrophaeus (BB15) and Bacillus subtilis (BB13). Sequence analysis of purified PCR products revealed homology with corresponding genes from other Bacillus sp. in the GenBank database. Primers specific for iturin D, surfactin, bacillomycin D, bacillomycin A, fengycin and zwittermycin A were used to amplify biosynthetic genes from these Bacillus strains using polymerase chain reaction (PCR). This study reveals the equivalent capability of different Bacillus strains from various microhabitats to produce the above-mentioned antibiotics and highlights the possibility of using some strains as potential biocontrol agents under different microhabitats distant from their original habitat. Furthermore, it will enable researchers to develop rational strategies for the application of the antagonists and their metabolites within an agroecosystem. Key words: Bacillus sp., antagonism, lipopeptides, polymerase chain reaction (PCR).

Antimicrobial activity of the seeds of Hyoscyamus niger L. (Henbane) on microorganisms isolated from urinary tract infections

Abstract: Objective: The methanol extracts obtained from the seeds of Hyoscyamus niger L. (Solanaceae) were investigated for their antimicrobial activities against the pathogens causing complicated urine tract infections. Methods: The seeds of plant were extracted with aqueous 60% methanol. The extract was screened against urinary tract pathogens (Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Candida albicans) by disc diffusion method and microdilution method. Some antibacterial and antifungal antibiotics were used as a positive reference standard to determine the sensitivity of the strains. Results: The extracts showed strong antimicrobial activity against Enterococcus faecalis, Klebsiella pneumoniae and Candida albicans with inhibition zones of 26.0, 19.0 and 16.0 mm, with MIC’s and MBC’s or MFC’s of 4.0(8.0), 32(64) and 64(128) µg/mL, respectively. Also, the extracts exhibited moderate activity against the other test microorganisms. Conclusion: Our findings support the use of Hyoscyamus niger L. in traditional medicine for the treatment against the urine tract pathogens.

Using the mycelium-covered cereals as an efficient inoculation method for rapamycin fermentation in a 15-L fermenter using Streptomyces hygroscopicus

Abstract: Rapamycin is produced from Streptomyces hygroscopicus, and was initially identified as an antifungal antibiotic. More recently, rapamycin has been found to have various medical applications, including in relation to immunosuppression and anti-aging. Due to its complex structure, biological production is the major route for commercialized rapamycin production. The conventional fermentation process requires a large seed fermenter for the inoculation process (in general, the volume of the seed fermenter is equal to 5–10 % that of the production fermenter), which presents challenges with regard to scaling up production, due to the high investment costs of seed fermenters. This study explored different inoculation strategies for rapamycin production in a 15-L agitation fermenter. The results indicated that solid-state fermentation (SSF) using barley as the substrate is a suitable method for the inoculation. The highest rapamycin concentration measured in the batch with SSF (barley) inoculated was about 520 mg/L, which was significantly higher than that of 400 mg/L obtained in the batch inoculated with 5 % liquid seed medium. Besides the higher rapamycin production, using SSF of barley as the inoculation method can greatly reduce both the labor and cost requirements. The usage of mycelium-covered barley as the solid substrate for the inoculation of 15-L fermenter leading to a higher rapamycin production compared to that of conventional liquid seed medium. The solid-state inoculation method can avoid both the intensive labor requirement and costly seed fermenter needed with the latter approach. This inoculation method thus has the potential to be applied to the large-scale production of rapamycin.

Cloning and Functional Analysis of tri14 in Trichoderma brevicompactum

Abstract: Trichodermin, one of the trichothecenes, is a potential antifungal antibiotic and a protein synthesis inhibitor. Trichodermin is synthesized mainly by Trichoderma brevicompactum, but the biosynthetic pathway has yet been completely elucidated. Our earlier transcriptome assay on the trichodermin synthesis in T. brevicompactum 0248 identified a unique tri14 transcript, designated Tbtri14, that was co-regulated with other tri cluster genes. However, the function of this gene remains unknown. In this study, the full cDNA and DNA sequence of Tbtri14 was isolated from T. brevicompactum 0248. It was found the Tbtri14 gene encodes 364 amino acids with a 59 bp intron. For gene function study, the Tbtri14 was deleted in the 0248 strain. The silencing of Tbtri14 dramatically increased the transcription of Tbtri11, it had little influence on the expression of Tbtri4 and Tbtri5 as well as the production of trichodermin in I”tri14 deletion mutants. This implied that Tbtri14 may not be directly involved in trichodermin biosynthesis. Instead, it may act as a gene regulator, such as a repressor for Tbtri11.

Anti-candidal activity of the Lavandula stoechas L. against pathogenic Candida species isolated from the hospital

Abstract: The purpose of this study is todetermine antimicrobial activity of extracts of L. stoechas L. againstfivedifferent pathogenic Candida species.As test microorganisms, species of Candida ( Candida albicans , Candida krusei , Candida tropicalis , Candida guilliermondii and Candida glabrata ) which were isolated from the patients appyling to Medical Faculty Hospital of Duzce University were used. Ethyl alcohol, chloroform and ethyl asetate extractions were acquired from the plant via Soxhlet. 25 μl, 50 μl and 75 μl of these extractions were impregnated into sterile discs and the anti-candidal activity spectrums were determined by using the disc diffusion method againts test microorganisms. As the control group standard antifungal antibiotics (Griseofulvin, Fluconazole, Amphotericin b, Miconazole, Nystatin, Flucytosine, Clotrimazole, Ketoconazole, Itraconazole) were used and the outcomes were compared.As a result, it is found out that the extractions acquired from L. stoechas L. plant have a very effective anti-candidal activity as compared with standard antibiotics.On the basis of our results, anti-candidal activity L. stoechas extracts more effective than standard antifungal antibiotics. So, this situation supports the ethnobotany usage of the plant. In addition to this, the potential extracts of the plant commonly used for alternative medicine may be also used for Candidemia treatment in future.

Fermentation medium for fermenting polyene macrolide antifungal antibiotic by streptomyces pluricolorescens and preparation method thereof

Abstract: The invention discloses a fermentation medium for fermenting polyene macrolide antifungal antibiotic by streptomyces pluricolorescens and a preparation method thereof and belongs to the technical field of fermentation engineering and biopesticide. The fermentation medium comprises a carbohydrate carbon source, an organic nitrogen source, an inorganic nitrogen source, an inorganic salt, yeast extract and amylase; the preparation method comprises the following steps: (1) uniformly mixing the carbohydrate carbon source and the amylase, adding water and heating to form a carbohydrate carbon source substance enzymatic hydrolysate; (2) mixing the organic nitrogen source, the inorganic nitrogen source, the inorganic salt, and the yeast extract, adding water and heating to form a nitrogen source substance mixed solution; and (3) mixing the carbohydrate carbon source substance enzymatic hydrolysate and the nitrogen source substance mixed solution, adding water and adjusting the pH value of the solution to 3-10 by hydrochloric acid and sodium hydroxide. The fermentation medium with high yield of polyene macrolide antibiotics and strong antibacterial action and a preparation method thereof for fermenting the polyene macrolide antifungal antibiotic by the streptomyces pluricolorescens are provided.