Juan Soliveri

Amine and ammonium functionalization of chloromethylsilane-ended dendrimers. Antimicrobial activity studies

Novel amine- and ammonium-terminated carbosilane dendrimers of type G(n)-[Si{CH(2)O-(C(6)H(4))-3-NMe(2)}](x) or G(n)-[Si{CH(2)O-(C(6)H(4))-3-NMe(3)(+)I(-)}](x) have been synthesized and characterized up to second generation by phenolysis of (chloromethyl)silyl-terminated dendrimers with 3-dimethylamine phenol and subsequent quaternization with methyl iodide. Quaternized carbosilane dendrimers are stable in protic solvents and can be solubilised in water after the addition of less than 1% of dimethyl sulfoxide. A study of the antimicrobial activity of these cationic dendrimers of first and second generation against both gram-positive and gram-negative bacteria is also described. The results obtained demonstrate that the new ammonium-terminated carbosilane dendrimers can be considered as multivalent biocides.

Growth and release of hydroxycinnamic acids from Brewer's spent grain by Streptomyces avermitilis CECT 3339

Streptomyces avermitilis CECT 3339 is grown on Brewer’s spent grain (BSG) and the production of feruloyl esterase (FAE) and (1→4)-β-d-xylan xilanohydrolase (xylanase) activities is studied over 5 days. Maximum level of xylanases was found at day 1. FAE activity on methyl ferulate reached a maximum level at day 2, whereas FAE activity on feruloylated oligosaccharides, either from wheat bran or sugar-beet pulp, was maximal at day 1. The cultures (1–5 days) from S. avermilitis CECT 3339 grown on BSG and on other two agro-industrial residues such as de-starched wheat bran and sugar-beet pulp were tested for the release of hydroxycinnamic acids (ferulic and p-coumaric acids) from BSG. Most ferulic acid (FA) was released when culture supernatants from day 1 and BSG as carbon source (43% of total alkali-extractable ferulic acid) and from day 2 and de-starched wheat bran as carbon source (41.2%) were used. The level of p-coumaric released in all cases was lower (<9% of total alkali-extractable p-coumaric acid; pCA). The importance of the time of growth for the enzyme production involved in the hydrolysis of BSG is discussed.

Carbosilane cationic dendrimers synthesized by thiol–ene click chemistry and their use as antibacterial agents

Cationic carbosilane dendrimers of generations 1–3 have been synthesized employing thiol–ene click chemistry. The obtained dendrimers present three different types of ammonium functions, two of them with the charge at the surface, –NH3+ and –NMe3+, and other with the charge internalized by the presence of ethylalcohol moieties, –[NMe2(CH2CH2OH)]+. The influence of –NMe3+ and –[NMe2(CH2CH2OH)]+ in dendrimer structure have been studied by molecular dynamics. The antibacterial properties of these families of dendrimers have been evaluated against Gram-positive (Staphylococcus aureus CECT 240) and Gram-negative (Escherichia coli CECT 515) bacterial strains, and the results have been compared with those obtained for related cationic carbosilane dendrimers functionalized by hydrosilylation reactions. These data show the relevance of the sulfur atom versus the silicon atom close to the dendrimer surface and the outer charge versus the inner charge. Finally, the stability of the most active first generation dendrimers vs. pH and temperature has also been studied.

Algoriphagus hitonicola sp. nov., isolated from an athalassohaline lagoon.

A Gram-negative, heterotrophic, aerobic, reddish-orange-pigmented, non-spore-forming, non-motile bacterial strain, designated 7-UAH(T), was isolated from salty water from the athalassohaline lagoon at El Hito, located in central Spain. The strain grew optimally at 37 degrees C and pH 7.0 and in the presence of 2.5 % NaCl. A polyphasic taxonomic study was carried out in order to characterize the strain in detail. Phylogenetic analyses based on 16S rRNA gene sequence comparisons indicated that strain 7-UAH(T) clustered within the branch constituted by species of the genus Hongiella, which were recently transferred to the genus Algoriphagus. Analysis of the polar lipid profile and DNA G+C content also supported placement of strain 7-UAH(T) within the genus Algoriphagus. On the basis of its phenotypic, chemotaxonomic and phylogenetic distinctiveness, strain 7-UAH(T) represents a novel species of the genus Algoriphagus, for which the name Algoriphagus hitonicola sp. nov. is proposed. The type strain is 7-UAH(T) (=CECT 7267(T) =CCM 7449(T)).

Halomonas ilicicola sp. nov., a moderately halophilic bacterium isolated from a saltern

A Gram-negative, heterotrophic, aerobic, pale orange-pigmented, non-endospore-forming and motile bacterial strain, designated strain SP8(T), was isolated from a salty water sample from the solar salterns of Santa Pola, located on the Mediterranean coast of Spain. The strain grew optimally at 37 degrees C, pH 6.5 and in the presence of 10 % NaCl. A polyphasic taxonomic study was conducted in order to characterize the strain in detail. Phylogenetic analyses based on 16S rRNA gene sequence comparisons indicated that strain SP8(T) clustered within the branch constituted by species of the genus Halomonas. The closest phylogenetic neighbours of strain SP8(T) were Halomonas muralis LMG 20969(T) (96.0 % sequence similarity), Halomonas pantelleriensis AAP(T) (95.9 %) and Halomonas campaniensis 5AG(T) (95.8 %). Phenotypic features, the fatty acid profile and the DNA G+C content of the novel strain further supported its placement in the genus Halomonas. On the basis of phenotypic, chemotaxonomic and phylogenetic distinctiveness, it is suggested that strain SP8(T) represents a novel species for which the name Halomonas ilicicola sp. nov. is proposed. The type strain is SP8(T) (=CECT 7331(T)=CCM 7522(T)=DSM 19980(T)).

Genomes of “Spiribacter”, a streamlined, successful halophilic bacterium

BackgroundThalassosaline waters produced by the concentration of seawater are widespread and common extreme aquatic habitats. Their salinity varies from that of sea water (ca. 3.5%) to saturation for NaCl (ca. 37%). Obviously the microbiota varies dramatically throughout this range. Recent metagenomic analysis of intermediate salinity waters (19%) indicated the presence of an abundant and yet undescribed gamma-proteobacterium. Two strains belonging to this group have been isolated from saltern ponds of intermediate salinity in two Spanish salterns and were named “Spiribacter”.ResultsThe genomes of two isolates of “Spiribacter” have been fully sequenced and assembled. The analysis of metagenomic datasets indicates that microbes of this genus are widespread worldwide in medium salinity habitats representing the first ecologically defined moderate halophile. The genomes indicate that the two isolates belong to different species within the same genus. Both genomes are streamlined with high coding densities, have few regulatory mechanisms and no motility or chemotactic behavior. Metabolically they are heterotrophs with a subgroup II xanthorhodopsin as an additional energy source when light is available.ConclusionsThis is the first bacterium that has been proven by culture independent approaches to be prevalent in hypersaline habitats of intermediate salinity (half a way between the sea and NaCl saturation). Predictions from the proteome and analysis of transporter genes, together with a complete ectoine biosynthesis gene cluster are consistent with these microbes having the salt-out-organic-compatible solutes type of osmoregulation. All these features are also consistent with a well-adapted fully planktonic microbe while other halophiles with more complex genomes such as Salinibacter ruber might have particle associated microniches.

Streptomyces avermitilis CECT 3339 produces a ferulic acid esterase able to release ferulic acid from sugar beet pulp soluble feruloylated oligosaccharides

Sugar beet pulp (SBP) is a waste product of the sugar industry which is rich in ferulic acid. Few ferulic acid esterases (FAEs) that are capable of releasing ferulic acid from SBP or from SBP soluble feruloylated oligosaccharides (SFO-SBP) have been described. Streptomyces avermitilis CECT 3339 was grown in medium containing SBP or destarched wheat bran (DSWB) as the carbon source. FAE activity was evaluated in terms of the micro-organisms capacity to release ferulic acid from DSWB, SBP, SFO-DSWB and SFO-SBP. S. avermitilis showed FAE activity in both media and was able to release ferulic acid from DSWB, SFO-DSWB and SFO-SBP. A comparison of the FAE activity detected in each medium indicated that different activities were induced by each type of carbon source.

Nutritional requirements for the production of pyrazoloisoquinolinone antibiotics by Streptomyces griseocarneus NCIMB 40447

Abstract This paper describes the effect of different nutrients on the production of pyrazoloisoquinolinone antibiotics (APHE) by Streptomyces griseocarneus. In a chemically defined medium with glucose as carbon and l-lysine as nitrogen source all APHE antibiotics (APHE-1 to -3) are produced, APHE-3 being the most abundant. Propionate and butyrate used as precursors with glucose as main carbon source increased the production of APHE-1 and -2, respectively. The presence of propionate or butyrate reduced the production of APHE-3. Results obtained in minimal medium supplemented with l-valine and l-histidine indicate a relationship between these amino acids and APHE biosynthesis. These data, together with those obtained in the presence of precursors of fatty acids, also show possible links with fatty acid biosynthesis. Different nutritional requirements were found for APHE-3 production in comparison with APHE-1 and APHE-2.

In vitro comparative assessment of different viability assays in Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites

The species of the genus Acanthamoeba are opportunistic protozoan parasites that cause different diseases in humans, such as amoebic keratitis and granulomatous encephalitis. The rise in the rate of Acanthamoeba keratitis, mainly due to the increase in contact lens wearers, turns the development of viability assays using a multi-well plate reader as a tool for screening new antiamoebic agents in vitro into an important goal. In our study, the viability assays PrestoBlue®, resazurin sodium salt, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) and CellTiter96® were tested for their suitability as time-saving alternatives to the classical manual or direct-counting method, assessing the effect of the antiamoebic agent chlorhexidine digluconate and temperature on Acanthamoeba castellanii (ATCC® 30234™) and Acanthamoeba polyphaga 2961. Although resazurin and MTT have already been previously used in amoeba viability assays to test the activities of antiamoebic agents in vitro, it is the first time that PrestoBlue® and CellTiter96® are used for this purpose. Results indicated that the viability assays were strain-dependent leading in some cases to an overestimation of the real situation of viable cells. This implies that each viability assay ought to be set up for each amoeba strain studied.

PA-5 and PA-7, pentaene and heptaene macrolide antibiotics produced by a new isolate of Streptoverticillium from Spanish soil

SummaryTwo antifungal antibiotics, named PA-5 and PA-7 were produced by an actinomycete strain, characterized and identified as Streptoverticillium sp 43/16. These antibiotics were extracted from mycelial cake with methanol and purified using different organic solvents and LH-20 Sephadex column chromatography. PA-5 and PA-7 were characterized as, a pentaene and a heptaene macrolide antibiotic, respectively. These antibiotics exhibit strong antifungal activity against pathogen yeasts and molds.