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1.
Six antimicrobial-producing seaweed-derived Bacillus strains were evaluated in vitro as animal probiotics, in comparison to two Bacillus from an EU-authorized animal probiotic product. Antimicrobial activity was demonstrated on solid media against porcine Salmonella and E. coli. The marine isolates were most active against the latter, had better activity than the commercial probiotics and Bacillus pumilus WIT 588 also reduced E. coli counts in broth. All of the marine Bacillus tolerated physiological concentrations of bile, with some as tolerant as one of the probiotics. Spore counts for all isolates remained almost constant during incubation in simulated gastric and ileum juices. All of the marine Bacillus grew anaerobically and the spores of all except one isolate germinated under anaerobic conditions. All were sensitive to a panel of antibiotics and none harbored Bacillus enterotoxin genes but all, except B. pumilus WIT 588, showed some degree of β-hemolysis. However, trypan blue dye exclusion and xCELLigence assays demonstrated a lack of toxicity in comparison to two pathogens; in fact, the commercial probiotics appeared more cytotoxic than the majority of the marine Bacillus. Overall, some of the marine-derived Bacillus, in particular B. pumilus WIT 588, demonstrate potential for use as livestock probiotics.  相似文献   

2.
The occurrence of Bacillus entomopathogenic bacteria on a Tunisian biodynamic farm was determined by examining 75 samples from olive tree (Olea europaea L.) habitats. A total of 40 Bacillus isolates were characterized according to their phenotypic, physiological and biochemical parameters. Isolates of the species Bacillus subtilis, Bacillus mycoides, Brevibacillus brevis, Paenibacillus polymyxa, Bacillus licheniformis, Bacillus sp. (1), Bacillus sp. (2) and a standard strain Btk HD-1 were used separately in feeding bioassays on fresh artificial diet against larvae of lepidopterans Prays oleae (Bernard) and Palpita unionalis (Hübner) and coleopterans Hylesinus oleiperda (F.) and Phloeotribus scarabaeoides (Bernard), which are olive tree pests. Larvae were successfully reared on an artificial diet with 25 g powdered olive tree leaves. Compared to the control data, only Btk and the isolates of B. licheniformis, P. polymyxa and B. brevis were entomopathogenic. Larval mortality assessed 7 days post-treatment showed high mortality rates with Btk to lepidopteran larvae (86.6% for P. oleae and 80.9% for P. unionalis) and low mortality against coleopteran pests. B. brevis isolates showed high mortality rates against P. oleae (up to 67.9%). B. licheniformis isolates caused up to 59.2% larval mortality for P. oleae and 43.6% for P. unionalis. Highest coleopteran mortality was achieved by P. polymyxa isolates (up to 55%). According to the 16S rDNA results, isolates of each of the three entomopathogenic strains were similar. Proteins in the strain supernatants were toxic to P. oleae larvae with LC50 values of 10.0 (B. brevis), 12.5 (B. licheniformis) and 37.6 μg/ml (P. polymyxa). Also, P. polymyxa showed an LC50 of 12.4 mg/l against P. scarabaeoides. Our results suggest that entomopathogenic Bacillus present locally in the biodynamic farm could be used in biological control programmes of olive tree pests.  相似文献   

3.
The bioflocculant-producing potentials of a marine bacteria isolated from the bottom sediment of Algoa Bay was investigated using standard methods. The 16S rDNA sequence analysis revealed 98% similarity to that of Bacillus sp. HXG-C1 and the nucleotide sequence was deposited in GenBank as Bacillus sp. Gilbert with accession number HQ537128. Bioflocculant was optimally produced when sucrose (72% flocculating activity) and ammonium chloride (91% flocculating activity) were used as sole sources of carbon and nitrogen, respectively; an initial pH 6.2 of the production medium; and Mg2+ as cation. Chemical analysis of the purified bioflocculant revealed the compound to be a polysaccharide.  相似文献   

4.
During our search for new natural products from the marine environment, we discovered a wide range of cyclic peptides from a marine Photobacterium, closely related to P. halotolerans. The chemical fingerprint of the bacterium showed primarily non-ribosomal peptide synthetase (NRPS)-like compounds, including the known pyrrothine antibiotic holomycin and a wide range of peptides, from diketopiperazines to cyclodepsipeptides of 500–900 Da. Purification of components from the pellet fraction led to the isolation and structure elucidation of four new cyclodepsipeptides, ngercheumicin F, G, H, and I. The ngercheumicins interfered with expression of virulence genes known to be controlled by the agr quorum sensing system of Staphylococcus aureus, although to a lesser extent than the previously described solonamides from the same strain of Photobacterium.  相似文献   

5.
New ecosystems are being actively mined for new bioactive compounds. Because of the large amount of unexplored biodiversity, bacteria from marine environments are especially promising. Further, host-associated microbes are of special interest because of their low toxicity and compatibility with host health. Here, we identified and characterized biosynthetic gene clusters encoding antimicrobial compounds in host-associated enterococci recovered from fecal samples of wild marine animals remote from human-affected ecosystems. Putative biosynthetic gene clusters in the genomes of 22 Enterococcus strains of marine origin were predicted using antiSMASH5 and Bagel4 bioinformatic software. At least one gene cluster encoding a putative bioactive compound precursor was identified in each genome. Collectively, 73 putative antimicrobial compounds were identified, including 61 bacteriocins (83.56%), 10 terpenes (13.70%), and 2 (2.74%) related to putative nonribosomal peptides (NRPs). Two of the species studied, Enterococcus avium and Enterococcus mundtti, are rare causes of human disease and were found to lack any known pathogenic determinants but yet possessed bacteriocin biosynthetic genes, suggesting possible additional utility as probiotics. Wild marine animal-associated enterococci from human-remote ecosystems provide a potentially rich source for new antimicrobial compounds of therapeutic and industrial value and potential probiotic application.  相似文献   

6.
Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S rRNA gene sequencing. Bacteria extracts were obtained with methanol and dichloromethane (1:1) extraction. The antioxidant activity of extracts was performed by quantification of total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae and Candida albicans. A total of 39 Bifurcaria bifurcata-associated bacteria were isolated and 33 were identified as Vibrio sp. (48.72%), Alteromonas sp. (12.82%), Shewanella sp. (12.26%), Serratia sp. (2.56%), Citricoccus sp. (2.56%), Cellulophaga sp. (2.56%), Ruegeria sp. (2.56%) and Staphylococcus sp. (2.56%). Six (15.38%) of the 39 bacteria Bifurcaria bifurcata-associated bacteria presented less than a 90% Basic Local Alignment Search Tool (BLAST) match, and some of those could be new. The highest antioxidant activity and antimicrobial activity (against B. subtilis) was exhibited by strain 16 (Shewanella sp.). Several strains also presented high antimicrobial activity against S. aureus, mainly belonging to Alteromonas sp. and Vibrio sp. There were no positive results against fungi and Gram-negative bacteria. Bifurcaria bifurcata epiphytic bacteria were revealed to be excellent sources of natural antioxidant and antimicrobial compounds.  相似文献   

7.
The search for new antimicrobial compounds has gained added momentum in recent years, paralleled by the exponential rise in resistance to most known classes of current antibiotics. While modifications of existing drugs have brought some limited clinical success, there remains a critical need for new classes of antimicrobial compound to which key clinical pathogens will be naive. This has provided the context and impetus to marine biodiscovery programmes that seek to isolate and characterize new activities from the aquatic ecosystem. One new antibiotic to emerge from these initiatives is the antibacterial compound tropodithietic acid (TDA). The aim of this study was to provide insight into the bioactivity of and the factors governing the production of TDA in marine Pseudovibrio isolates from a collection of marine sponges. The TDA produced by these Pseudovibrio isolates exhibited potent antimicrobial activity against a broad spectrum of clinical pathogens, while TDA tolerance was frequent in non-TDA producing marine isolates. Comparative genomics analysis suggested a high degree of conservation among the tda biosynthetic clusters while expression studies revealed coordinated regulation of TDA synthesis upon transition from log to stationary phase growth, which was not induced by TDA itself or by the presence of the C10-acyl homoserine lactone quorum sensing signal molecule.  相似文献   

8.
Forty four marine actinomycetes of the family Microccocaceae isolated from sponges collected primarily in Florida Keys (USA) were selected from our strain collection to be studied as new sources for the production of bioactive natural products. A 16S rRNA gene based phylogenetic analysis showed that the strains are members of the genera Kocuria and Micrococcus. To assess their biosynthetic potential, the strains were PCR screened for the presence of secondary metabolite genes encoding nonribosomal synthetase (NRPS) and polyketide synthases (PKS). A small extract collection of 528 crude extracts generated from nutritional microfermentation arrays was tested for the production of bioactive secondary metabolites against clinically relevant strains (Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii and Candida albicans). Three independent isolates were shown to produce a new anti-MRSA bioactive compound that was identified as kocurin, a new member of the thiazolyl peptide family of antibiotics emphasizing the role of this family as a prolific resource for novel drugs.  相似文献   

9.
Radopholus similis is a serious threat to black pepper (Piper nigrum L.) cultivation being the main causal organism of slow decline disease. Because of its migratory nature most fungal and bacterial antagonists are ineffective in suppressing R. similis. The presence of a number of endophytic bacteria in black pepper tissues has been proved in earlier studies. This study was undertaken to evaluate the bacteria isolated from black pepper for suppressing R. similis. In vitro and in vivo screenings were used initially to identify the efficient strains of endophytic bacteria that suppress R. similis. Seventy four isolates of endophytic bacteria obtained from black pepper were screened against R. similis by various bioassays. Results of the in vitro experiments were inconclusive and did not match the rest of the studies. However, six isolates were short-listed based on the preliminary in vivo screening and further tested in an evaluation trial using three varieties of black pepper. Irrespective of the varieties, significantly higher nematode suppression was observed with one isolate (TC 10) followed by another (BP 17). These isolates were identified to the species level by sequence analysis of the 16S rRNA gene. The results showed that these isolates shared 99% identity with Bacillus megaterium and Curtobacterium luteum, respectively. More studies are required to understand their mode of action as well as the dose–response relationship with nematodes.  相似文献   

10.
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11.
Cyanobacteria produce a great variety of non-ribosomal peptides. Among these compounds, both acute toxins and potential drug candidates have been reported. The profile of the peptides, as a stable and specific feature of an individual strain, can be used to discriminate cyanobacteria at sub-population levels. In our work, liquid chromatography-tandem mass spectrometry was used to elucidate the structures of non-ribosomal peptides produced by Nodularia spumigena from the Baltic Sea, the coastal waters of southern Australia and Lake Iznik in Turkey. In addition to known structures, 9 new congeners of spumigins, 4 aeruginosins and 12 anabaenopeptins (nodulapeptins) were identified. The production of aeruginosins by N. spumigena was revealed in this work for the first time. The isolates from the Baltic Sea appeared to be the richest source of the peptides; they also showed a higher diversity in peptide profiles. The Australian strains were characterized by similar peptide patterns, but distinct from those represented by the Baltic and Lake Iznik isolates. The results obtained with the application of the peptidomic approach were consistent with the published data on the genetic diversity of the Baltic and Australian populations.  相似文献   

12.
A total of 16 marine strains belonging to the genus Arenibacter, recovered from diverse microbial communities associated with various marine habitats and collected from different locations, were evaluated in degradation of natural polysaccharides and chromogenic glycosides. Most strains were affiliated with five recognized species, and some presented three new species within the genus Arenibacter. No strains contained enzymes depolymerizing polysaccharides, but synthesized a wide spectrum of glycosidases. Highly active β-N-acetylglucosaminidases and α-N-acetylgalactosaminidases were the main glycosidases for all Arenibacter. The genes, encoding two new members of glycoside hydrolyses (GH) families, 20 and 109, were isolated and characterized from the genomes of Arenibacter latericius. Molecular genetic analysis using glycosidase-specific primers shows the absence of GH27 and GH36 genes. A sequence comparison with functionally-characterized GH20 and GH109 enzymes shows that both sequences are closest to the enzymes of chitinolytic bacteria Vibrio furnissii and Cellulomonas fimi of marine and terrestrial origin, as well as human pathogen Elisabethkingia meningoseptica and simbionts Akkermansia muciniphila, gut and non-gut Bacteroides, respectively. These results revealed that the genus Arenibacter is a highly taxonomic diverse group of microorganisms, which can participate in degradation of natural polymers in marine environments depending on their niche and habitat adaptations. They are new prospective candidates for biotechnological applications due to their production of unique glycosidases.  相似文献   

13.
Bacteriocins are attracting increased attention as an alternative to classic antibiotics in the fight against infectious disease and multidrug resistant pathogens. Bacillus subtilis strain MMA7 isolated from the marine sponge Haliclona simulans displays a broad spectrum antimicrobial activity, which includes Gram-positive and Gram-negative pathogens, as well as several pathogenic Candida species. This activity is in part associated with a newly identified lantibiotic, herein named as subtilomycin. The proposed biosynthetic cluster is composed of six genes, including protein-coding genes for LanB-like dehydratase and LanC-like cyclase modification enzymes, characteristic of the class I lantibiotics. The subtilomycin biosynthetic cluster in B. subtilis strain MMA7 is found in place of the sporulation killing factor (skf) operon, reported in many B. subtilis isolates and involved in a bacterial cannibalistic behaviour intended to delay sporulation. The presence of the subtilomycin biosynthetic cluster appears to be widespread amongst B. subtilis strains isolated from different shallow and deep water marine sponges. Subtilomycin possesses several desirable industrial and pharmaceutical physicochemical properties, including activity over a wide pH range, thermal resistance and water solubility. Additionally, the production of the lantibiotic subtilomycin could be a desirable property should B. subtilis strain MMA7 be employed as a probiotic in aquaculture applications.  相似文献   

14.
Although some alginate lyases have been isolated from marine bacteria, alginate lyases-excreting bacteria from the Arctic alga have not yet been investigated. Here, the diversity of the bacteria associated with the brown alga Laminaria from the Arctic Ocean was investigated for the first time. Sixty five strains belonging to nine genera were recovered from six Laminaria samples, in which Psychrobacter (33/65), Psychromonas (10/65) and Polaribacter (8/65) were the predominant groups. Moreover, 21 alginate lyase-excreting strains were further screened from these Laminaria-associated bacteria. These alginate lyase-excreting strains belong to five genera. Psychromonas (8/21), Psedoalteromonas (6/21) and Polaribacter (4/21) are the predominant genera, and Psychrobacter, Winogradskyella, Psychromonas and Polaribacter were first found to produce alginate lyases. The optimal temperatures for the growth and algiante lyase production of many strains were as low as 10–20 °C, indicating that they are psychrophilic bacteria. The alginate lyases produced by 11 strains showed the highest activity at 20–30 °C, indicating that these enzymes are cold-adapted enzymes. Some strians showed high levels of extracellular alginate lyase activity around 200 U/mL. These results suggest that these algiante lyase-excreting bacteria from the Arctic alga are good materials for studying bacterial cold-adapted alginate lyases.  相似文献   

15.
Dust has been widely recognised as an important source of nutrients in the marine environment and as a vector for transporting pathogenic microorganisms. Disturbingly, in the wake of a dust storm event along the eastern Australian coast line in 2009, the Continuous Plankton Recorder collected masses of fungal spores and mycelia (~150,000 spores/m3) forming a floating raft that covered a coastal area equivalent to 25 times the surface of England. Cultured A. sydowii strains exhibited varying metabolite profiles, but all produced sydonic acid, a chemotaxonomic marker for A. sydowii. The Australian marine fungal strains share major metabolites and display comparable metabolic diversity to Australian terrestrial strains and to strains pathogenic to Caribbean coral. Secondary colonisation of the rafts by other fungi, including strains of Cladosporium, Penicillium and other Aspergillus species with distinct secondary metabolite profiles, was also encountered. Our bioassays revealed that the dust-derived marine fungal extracts and known A. sydowii metabolites such as sydowic acid, sydowinol and sydowinin A adversely affect photophysiological performance (Fv/Fm) of the coral reef dinoflagellate endosymbiont Symbiodinium. Different Symbiodinium clades exhibited varying sensitivities, mimicking sensitivity to coral bleaching phenomena. The detection of such large amounts of A. sydowii following this dust storm event has potential implications for the health of coral environments such as the Great Barrier Reef.  相似文献   

16.
2-(2′,4′-Dibromophenoxy)-4,6-dibromophenol isolated from the marine sponge Dysidea granulosa (Bergquist) collected off the coast of Lakshadweep islands, Indian Ocean, exhibited potent and broad spectrum in-vitro antibacterial activity, especially against methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), vancomycin resistant Enterococci (VRE), vancomycin sensitive Enterococci (VSE) and Bacillus spp. Minimal inhibitory concentration (MIC) was evaluated against 57 clinical and standard strains of Gram positive and Gram negative bacteria. The observed MIC range was 0.117–2.5 μg/mL against all the Gram positive bacteria and 0.5–2 μg/mL against Gram negative bacteria. The in-vitro antibacterial activity observed was better than that of the standard antibiotic linezolid, a marketed anti-MRSA drug. The results establish 2-(2′,4′-dibromophenoxy)-4,6-dibromophenol, as a potential lead molecule for anti-MRSA and anti-VRE drug development.  相似文献   

17.
The marine brown alga Halidrys siliquosa is known to produce compounds with antifouling activity against several marine bacteria. The aim of this study was to evaluate the antimicrobial and antibiofilm activity of organic extracts obtained from the marine brown alga H. siliquosa against a focused panel of clinically relevant human pathogens commonly associated with biofilm-related infections. The partially fractionated methanolic extract obtained from H. siliquosa collected along the shores of Co. Donegal; Ireland; displayed antimicrobial activity against bacteria of the genus Staphylococcus; Streptococcus; Enterococcus; Pseudomonas; Stenotrophomonas; and Chromobacterium with MIC and MBC values ranging from 0.0391 to 5 mg/mL. Biofilms of S. aureus MRSA were found to be susceptible to the algal methanolic extract with MBEC values ranging from 1.25 mg/mL to 5 mg/mL respectively. Confocal laser scanning microscopy using LIVE/DEAD staining confirmed the antimicrobial nature of the antibiofilm activity observed using the MBEC assay. A bioassay-guided fractionation method was developed yielding 10 active fractions from which to perform purification and structural elucidation of clinically-relevant antibiofilm compounds.  相似文献   

18.
A new meroditerpene, sartorypyrone C (5), was isolated, together with the known tryptoquivalines l (1a), H (1b), F (1c), 3′-(4-oxoquinazolin-3-yl) spiro[1H-indole-3,5′]-2,2′-dione (2) and 4(3H)-quinazolinone (3), from the culture of the marine sponge-associated fungus Neosartorya paulistensis (KUFC 7897), while reexamination of the fractions remaining from a previous study of the culture of the diseased coral-derived fungus N. laciniosa (KUFC 7896) led to isolation of a new tryptoquivaline derivative tryptoquivaline T (1d). Compounds 1a–d, 2, 3, and 5, together with aszonapyrones A (4a) and B (4b), chevalones B (6) and C (7a), sartorypyrones B (7b) and A (8), were tested for their antibacterial activity against four reference strains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa), as well as the environmental multidrug-resistant isolates. Only aszonapyrone A (4a) and sartorypyrone A (8) exhibited significant antibacterial activity as well as synergism with antibiotics against the Gram-positive multidrug-resistant strains. Antibiofilm assays of aszonapyrone A (4a) and sartorypyrone A (8) showed that practically no biofilm was formed in the presence of their 2× MIC and MIC. However, the presence of a sub-inhibitory concentration of ½ MIC of 4a and 8 was found to increase the biofilm production in both reference strain and the multidrug-resistant isolates of S. aureus.  相似文献   

19.
Two new isocoumarin derivatives, including a new 5-hydroxy-8-methyl-2H, 6H-pyrano[3,4-g]chromen-2,6-dione (1) and 6,8-dihydroxy-3,7-dimethylisocoumarin (2b), a new chevalone derivative, named chevalone E (3), and a new natural product pyripyropene S (6) were isolated together with 6, 8-dihydroxy-3-methylisocoumarin (2a), reticulol (2c), p-hydroxybenzaldehyde, chevalone B, chevalone C, S14-95 (4), and pyripyropene E (5) from the ethyl acetate extract of the undescribed marine sponge-associated fungus Aspergillus similanensis KUFA 0013. The structures of the new compounds were established based on 1D and 2D NMR spectral analysis, and in the case of compound 3, X-ray analysis was used to confirm its structure and the absolute configuration of its stereogenic carbons. Compounds 1, 2a–c and 3–6 were evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria, Candida albicans ATCC 10231, and multidrug-resistant isolates from the environment. Chevalone E (3) was found to show synergism with the antibiotic oxacillin against methicillin-resistant Staphylococcus aureus (MRSA).  相似文献   

20.
Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins) were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp.).  相似文献   

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