Alkalibacillus almallahensis sp. nov., a halophilic bacterium isolated from an inland solar saltern.

A halophilic, Gram-staining-positive, non-motile, endospore forming rod-shaped bacterial strain, S1LM8(T), was isolated from a sediment sample collected from an inland solar saltern located in La Malahá, Granada (Spain). Growth was observed in media containing 7.5-30% total salts (optimum 15% total salts), at pH 7-10 (optimum pH 8) and at 15-50 °C (optimum 35-38 °C). The predominant isoprenoid quinone was MK-7. It contained A1γ-type peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0), anteiso-C(17 : 0) and iso-C(16 : 0). The G+C content of its genomic DNA was 38.2 mol%. The affiliation of strain S1LM8(T) with the species of the genus Alkalibacillus was determined by 16S rRNA gene sequence comparison. The most closely related species were Alkalibacillus halophilus YIM 012(T) with 99.8% similarity, Alkalibacillus salilacus BH163(T) with 99.8% similarity and Alkalibacillus flavidus ISL-17(T) with 98.1% similarity between their 16S rRNA gene sequences. However, DNA-DNA relatedness between the novel isolate and the related species of the genus Alkalibacillus was less than 34%. Based on the phylogenetic, phenotypic and chemotaxonomic features, a novel species, Alkalibacillus almallahensis sp. nov. is proposed. The type strain is S1LM8(T) ( = CECT 8373(T) = DSM 27545(T)).

Stability of lactobacilli encapsulated in various microbial polymers.

Various microbial polymers, namely xanthan gum, gellan gum, pullulan gum and jamilan, were tested as a suitable encapsulating material for Lactobacillus plantarum CRL 1815 and Lactobacillus rhamnosus ATCC 53103. Resulting capsules were also studied for their pH and simulated gastrointestinal conditions tolerance. The morphology of the microcapsules was studied using scanning electron microscopy. pH tolerance was tested at pH 2.0, 3.5, 5.0 and 6.5 over a 6h incubation period. Simulated gastrointestinal conditions were assayed with simulated gastric and pancreatic juices and simulated bile over a 24h incubation period. Suspensions of probiotic organisms were used as a control. The results from encapsulation with microbial polymers indicate that mixtures of 1% xanthan gum with 0.75% gellan gum and 1% jamilan with 1% gellan gum were the most suitable for microencapsulation. Results for the pH tolerance tests showed no improvement in the viability of cells in relation to the control, except for pH 2.0 where lactobacilli encapsulated in xanthan:gellan gum (1%:0.75%) prolonged their viability by 6h exposure. Xanthan:gellan gum (1%:0.75%) was the most effective of the encapsulating materials tested in protecting L. plantarum and L. rhamnosus against simulated bile, improving its viability in 1-2 logCFU when compared with control. The results of this study suggest that microbial polymers are an interesting source of encapsulating material that should be taken into account for prospective studies of probiotic encapsulation for oral delivery applications.

Delivery systems for natural antioxidant compounds: Archaeosomes and archaeosomal hydrogels characterization and release study.

The aim of this study was to use archaeosomes, a novel kind of liposomes made up by archaeal polar lipids, both multilamellars (MLVs) and unilamellars (SUVs), as a topical delivery system for natural antioxidant compounds recovered from olive mill waste. For comparative purpose an analogue formulation of phosphatidylcholine liposomes was prepared. SUVs were smaller than MLVs ones, showing size values smaller than 200nm, which was maintained during the stability study. Transmission electron microscopy showed spherical morphology for conventional liposomes while archaeosomes had more irregular membranes. Vesicle encapsulation efficiency was quite similar in both formulations and was enough to ensure a good antioxidant activity. Stability studies were performed one month after the preparation of formulations, which showed a high stability with no change in the initial characteristics of the suspensions. Furthermore, the possibility of incorporating the liposomal suspensions in different excipients (Carbopol-940(®) and Pluronic-127(®)) for topical administration was studied. In order to evaluate the release behaviour of the different systems prepared, in vitro diffusion studies were carried out using vertical diffusion Franz cells. In both cases the incorporation of the vesicles into the gels lead in a sustained release for 24h. Archaeosome gels released a similar amount of phenolic compounds regardless the excipient used, while in liposomal gels great release differences were found between carbopol and pluronic gel.

Marinobacter oulmenensis sp. nov., a moderately halophilic bacterium isolated from brine of a salt concentrator.

A Gram-negative, aerobic, moderately halophilic bacterium, designated Set74(T), was isolated from brine of a salt concentrator at Ain Oulmene, Algeria. The strain grew optimally at 37-40 °C, at pH 6.5-7.0 and with 5-7.5 % (w/v) NaCl and used various organic compounds as sole carbon, nitrogen and energy sources. Ubiquinone 9 (Q-9) was the major lipoquinone. The main cellular fatty acids were C16:0, C18:1ω9c, summed feature 7 (ECL 18.846; C19:0 cyclo ω10c and/or C19:1ω6c), C12:0 3-OH, C16:1ω9c, C18:0 and C12:0. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was 57.4 mol%. The 16S rRNA gene sequence analysis indicated that strain Set74(T) was a member of the genus Marinobacter. The closest relatives of strain Set74(T) were Marinobacter santoriniensis NKSG1(T) (97.5 % 16S rRNA gene sequence similarity) and Marinobacter koreensis DD-M3(T) (97.4 %). DNA-DNA relatedness between strain Set74(T) and M. santoriniensis DSM 21262(T) and M. koreensis DSM 17924(T) was 45 and 37 %, respectively. On the basis of the phenotypic, chemotaxonomic and phylogenetic features, a novel species, Marinobacter oulmenensis sp. nov., is proposed. The type strain is Set74(T) ( = CECT 7499(T)  = DSM 22359(T)).

Archaeosomes as carriers for topical delivery of betamethasone dipropionate: in vitro skin permeation study.

A comparative study between archaeosomes, lipid lamellar vesicles made from archaea polar lipids, and conventional phospholipids liposomes was carried out, aiming at evaluating the properties and the potential of archaeosomes as novel colloidal carriers for effective drug delivery to the skin. Betamethasone dipropionate (BMD)-loaded archaeosomes and conventional liposomes were prepared by the thin-lipid film and sonication procedures, using, respectively, archaeal lipids extracted from archaea Halobacterium salinarum and enriched soy phosphatidylcholine. Vesicular formulations were characterized by assessing vesicle size, zeta potential, incorporation efficiency, and morphology. In order to investigate the effect of the incorporation in the two different colloidal carrier systems on the (trans)dermal delivery of BMD, in vitro drug permeation studies through full-thickness pig skin were carried out by using Franz diffusion vertical cells by testing both archaeal and liposomal dispersions. Interestingly, archaeosomes appeared to be the most effective carriers for the model drug, achieveing a major drug penetration and accumulation in the skin strata, especially in the epidermis. This can, presumably, be due to the enhanced archaeosomal bilayer fluidity, as indicated by the rheological studies that provided insight into the viscoelastic properties of all the studied systems. The available data suggest that suitably developed archaeosomes may hold great promise as delivery vehicles for topical applications.

Marinobacter lacisalsi sp. nov., a moderately halophilic bacterium isolated from the saline-wetland wildfowl reserve Fuente de Piedra in southern Spain.

A Gram-negative, non-spore-forming, motile, moderately halophilic, aerobic, rod-shaped bacterium, designated strain FP2.5(T), was isolated from the inland hypersaline lake Fuente de Piedra, a saline-wetland wildfowl reserve located in the province of Málaga in southern Spain. Strain FP2.5(T) was subjected to a polyphasic taxonomic study. It produced colonies with a light-yellow pigment. Strain FP2.5(T) grew at salinities of 3-15 % (w/v) and at temperatures of 20-40 degrees C. The pH range for growth was 5-9. Strain FP2.5(T) was able to utilize various organic acids as sole carbon and energy source. Its major fatty acids were C(16 : 0), C(18 : 1)omega9c and C(16 : 1)omega9c. The DNA G+C content was 58.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain FP2.5(T) appeared to be a member of the genus Marinobacter and clustered closely with the type strains of Marinobacter segnicrescens, Marinobacter bryozoorum and Marinobacter gudaonensis (levels of 16S rRNA gene sequence similarity of 98.1, 97.4 and 97.2 %, respectively). However, DNA-DNA relatedness between the new isolate and the type strains of its closest related Marinobacter species was low; levels of DNA-DNA relatedness between strain FP2.5(T) and M. segnicrescens LMG 23928(T), M. bryozoorum DSM 15401(T) and M. gudaonensis DSM 18066(T) were 36.3, 32.1 and 24.9 %, respectively. On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness data, strain FP2.5(T) is considered to represent a novel species of the genus Marinobacter, for which the name Marinobacter lacisalsi sp. nov. is proposed. The type strain is FP2.5(T) (=CECT 7297(T)=LMG 24237(T)).

Halomicrobium katesii sp. nov., an extremely halophilic archaeon.

Two extremely halophilic archaea, strains Al-5(T) and K-1, were isolated from Lake Tebenquiche (Atacama Saltern, Chile) and Ezzemoul sabkha (Algeria), respectively. Cells of the two strains were short-rod-shaped and Gram-negative; colonies were orange-pigmented. They grew optimally at 37-40 degrees C and pH 7.0-7.5 in the presence of 25 % (w/v) NaCl. Magnesium was not required. Polar lipid analysis revealed the presence of phosphatidylglycerol and phosphatidylglycerophosphate methyl ester, the absence of phosphatidylglycerosulfate, and the presence of sulfated diglycosyl diether and diether diglycosyl as the sole glycolipids. DNA G+C contents of strains Al-5(T) and K-1 were 52.4 and 52.9 mol% (T(m) method), respectively. 16S rRNA gene sequence comparison with database sequences showed that strains Al-5(T) and K-1 were most closely related to Halomicrobium mukohataei DSM 12286(T) (similarities of 97.5 and 96.9 %, respectively). DNA-DNA hybridization indicated that strains Al-5(T) and K-1 were members of a single species. However, DNA-DNA relatedness to Halomicrobium mukohataei was 55.7+/-2.5 %. A comparative analysis of phenotypic characteristics and DNA-DNA hybridization between the isolates and Halomicrobium mukohataei DSM 12286(T) supported the conclusion that Al-5(T) and K-1 represent a novel species within the genus Halomicrobium, for which the name Halomicrobium katesii sp. nov. is proposed. The type strain is Al-5(T) (=CECT 7257(T)=DSM 19301(T)).

Administration of Lactobacillus casei and Lactobacillus plantarum affects the diversity of murine intestinal lactobacilli, but not the overall bacterial community structure.

Lactobacilli are normal inhabitants of the gastrointestinal tract (GIT) of many mammalian hosts. Their administration as probiotics in functional foods is currently a frequent practice, mainly because of their benefits to host health. It is therefore of interest to study the impact of administration of exogenous strains of Lactobacillus normally used as probiotics upon endogenous microbial populations. For this purpose, fecal and intestinal tissue samples were analyzed in a mouse model fed with a mixture of Lactobacillus plantarum and Lactobacillus casei isolated from commercially available dairy products. The murine intestinal microbiota was studied by means of cultivation-independent 16S rRNA gene-targeted techniques, namely denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of clone libraries. Multivariate statistical analysis was used to integrate datasets obtained from the different techniques applied. Whereas no differences were detected in the composition of the overall fecal bacterial community, changes were observed for intestinal tissue samples. Moreover, an increase in the diversity of gut lactobacilli was observed in fecal as well as intestinal tissue samples when mice received the mixture of L. casei and L. plantarum.

Characterisation of Paenibacillus jamilae strains that produce exopolysaccharide during growth on and detoxification of olive mill wastewaters.

A total of 10 bacterial strains were isolated from a compost of corn treated with olive mill wastewaters (OMW) and selected by their capacity to synthesize exopolysaccharides (EPS). Morphological, physiological, biochemical and nutritional tests were used for a phenotypic study. A numerical analysis showed that all strains were 90% similar to each other. A DNA-DNA hybridization assay confirmed that all the strains belonged to Paenibacillus jamilae species. All the characterized strains were able to produce EPS growing on OMW batch cultures. The strain which was able to produce the highest EPS yield was chosen to perform an assay for testing its putative detoxifying activity, and it showed to reduce more than half the toxic capacity of the OMW. The results presented in this study, indicated the possible perspectives for using these bacterial strains to produce EPS and contribute to the bioremediation of the waste waters that are produced in the olive oil elaboration process.

Chromohalobacter salarius sp. nov., a moderately halophilic bacterium isolated from a solar saltern in Cabo de Gata, Almeria, southern Spain.

A moderately halophilic, Gram-negative bacterium (strain CG4.1(T)), which was isolated from a solar saltern at Cabo de Gata, a wildlife reserve located in the province of Almería, southern Spain, was subjected to a polyphasic taxonomic study. This organism was an aerobic, motile rod that produced colonies with a yellow pigment. Strain CG4.1(T) grew at salinities of 3-25 % (w/v), at 15-45 degrees C and at pH 5-9. The organism reduced nitrate, hydrolysed starch and had phenylalanine deaminase activity. The major fatty acids were C(18 : 1)omega7c, C(16 : 0) and C(19 : 0) cyclo omega8c. The DNA G+C content was 63.6 mol%. On the basis of phenotypic and phylogenetic data, strain CG4.1(T) appears to be a member of the genus Chromohalobacter and clustered closely with Chromohalobacter species, with 95-96 % similarity between their 16S rRNA gene sequences. However, DNA-DNA relatedness between the isolate and the type strains of Chromohalobacter species was low. Therefore, it is proposed that strain CG4.1(T) represents a novel species, Chromohalobacter salarius sp. nov. The type strain is strain CG4.1(T) (=CECT 5903(T)=LMG 23626(T)).

Virgibacillus olivae sp. nov., isolated from waste wash-water from processing of Spanish-style green olives.

Four bacterial strains (E(30)8(T), E(55)49, I(30)77 and N(30)129) were isolated from the residual wash-water produced during the processing of Spanish-style green table olives. The isolates were subjected to a polyphasic taxonomic study using phenotypic, phylogenetic and genotypic methods. The bacteria were Gram-positive, spore-forming rods. Moreover, they were heterotrophs that were able to utilize cellobiose, glucose, mannose and rhamnose as carbon sources. The G+C content of their genomic DNA ranged from 30.7 to 33.4 mol%. The major cellular fatty acids found in strain E(30)8(T) were iso-C(15 : 0), anteiso-C(15 : 0), iso-C(17 : 0) and anteiso-C(17 : 0). DNA-DNA hybridization shows 76.2-88.3 % relatedness among the four strains. The 16S rRNA gene sequence of isolate E(30)8(T) shows that it belongs to the genus Virgibacillus, with the highest sequence similarity (99 %) to Virgibacillus marismortui 123(T). However, phenotypic differences and DNA-DNA relatedness between strain E(30)8(T) and V. marismortui ATCC 700626(T) of less than 47 % suggest the placement of these strains within a novel species of the genus Virgibacillus. The name Virgibacillus olivae sp. nov. is proposed, with strain E(30)8(T) (=LMG 23503(T)=DSM 18098(T)) as the type strain.

Halomonas indalinina sp. nov., a moderately halophilic bacterium isolated from a solar saltern in Cabo de Gata, Almeria, southern Spain.

A moderately halophilic bacterium, strain CG2.1T, isolated from a solar saltern at Cabo de Gata, a wildlife reserve located in the province of Almería, southern Spain, was subjected to a polyphasic taxonomic study. This organism was an aerobic, motile, Gram-negative rod that produced orange-pigmented colonies. Strain CG2.1T was able to grow at salinities of 3-25 % (w/v) and at temperatures of 15-40 degrees C. The pH range for growth was 5-9. Strain CG2.1T was a heterotroph capable of utilizing various carbohydrates as carbon sources. The organism reduced nitrate and showed phenylalanine deaminase activity. The major fatty acids were C(18 : 1)omega7c, C(16 : 0) and C(19 : 0) cyclo omega8c. The DNA G+C content was 60.9 mol%. On the basis of the phenotypic and phylogenetic data, strain CG2.1T appeared to be a member of the genus Halomonas and clustered closely with Halomonas marisflavi (97.1 % 16S rRNA gene sequence similarity). However, the level of DNA-DNA relatedness between the novel isolate and the most closely related Halomonas species was low. On the basis of these data, strain CG2.1T represents a novel member of the genus Halomonas, for which the name Halomonas indalinina is proposed. The type strain is CG2.1T (=CECT 5902T=LMG 23625T).

Production and characterization of the exopolysaccharide produced by Paenibacillus jamilae grown on olive mill-waste waters.

Paenibacillus jamilae, a strain isolated from compost prepared with olive-mill wastewaters, produced an extracellular polysaccharide (EPS) when it was grown in a culture containing olive-mill waste waters (OMWW) as sole carbon and energy sources. Maximal EPS production in 100 mL batch-culture experiments (5.1 g L(-1)) was reached with a concentration of 80% of OMWW as fermentation substrate (v/v). Although an inhibitory effect was observed on growth and EPS production when OMWW concentration was increased, an appreciable amount of EPS (2.7 g L(-1)) was produced with undiluted OMWW. Sepharose CL-2B chromatography showed that the EPS presented two fractions, EPS I (>2000 kDa) and EPS II (500 kDa). Both fractions were characterized by GC-MS as two different acidic heteropolysaccharides containing glucose, galactose and mannose as the major components. The performed study made evident the possibility of using OMWW as substrate for the production of EPS by P. jamilae with a satisfactory yield.

Salicola salis sp. nov., an extremely halophilic bacterium isolated from Ezzemoul sabkha in Algeria.

A novel, extremely halophilic bacterium was isolated from brine samples collected from Ezzemoul sabkha in north-east Algeria. Cells of this isolate, designated B2T, were Gram-negative, rod-shaped and motile. Growth occurred between 10 and 25% (w/v) NaCl and the isolate grew optimally at 15-20% (w/v) NaCl. The pH range for growth was 6.0-9.0 with an optimum at pH 7.0-7.5. The predominant fatty acids were C16:0 and C18:1omega9c. Other fatty acids present were C16:1omega9c, C18:0 10-methyl, C12:0 3-OH, C10:0 and C12:0. The G+C content of the genomic DNA was 56.0 mol%. 16S rRNA gene sequence analysis indicated that strain B2T was closely related to Salicola marasensis in the Gammaproteobacteria. The level of 16S rRNA gene sequence similarity between strain B2T and the type strain of Salicola marasensis was 99%. DNA-DNA hybridization experiments between strain B2T and Salicola marasensis indicated a level of relatedness of 52%. The phenotypic characteristics of strain B2T allowed its differentiation from recognized species of the genus Salicola. Strain B2T was able to hydrolyse starch but not aesculin. It was unable to use carbohydrates and could not use citrate, pyruvate or succinate as sole carbon and energy sources. On the basis of the polyphasic data presented, strain B2T is considered to represent a novel species of the genus Salicola, for which the name Salicola salis sp. nov. is proposed. The type strain is B2T (=CECT 7106T=LMG 23122T).

Production of a metal-binding exopolysaccharide by Paenibacillus jamilae using two-phase olive-mill waste as fermentation substrate.

The present study investigated the use of two-phase olive mill waste (TPOMW) as substrate for the production of exopolysaccharide (EPS) by the endospore-forming bacilli Paenibacillus jamilae. This microorganism was able to grow and produce EPS in aqueous extracts of TPOMW as a unique source of carbon. The effects of substrate concentration and the addition of inorganic nutrients were investigated. Maximal polymer yield in 100-ml batch-culture experiments (2 g l(-1)) was obtained in cultures prepared with an aqueous extract of 20% TPOMW (w/v). An inhibitory effect was observed on growth and EPS production when TPOMW concentration was increased. Nutrient supplementation (nitrate, phosphate, and other inorganic nutrients) did not increase yield. Finally, an adsorption experiment of Pb (II), Cd (II), Cu (II), Zn (II), Co (II), and Ni (II) by EPS is reported. Lead was preferentially complexed by the polymer, with a maximal uptake of 230 mg/g EPS.

Halorubrum ezzemoulense sp. nov., a halophilic archaeon isolated from Ezzemoul sabkha, Algeria.

A novel extremely halophilic archaeon was isolated from Ezzemoul sabkha, Algeria. The strain, designated 5.1(T), was neutrophilic, motile and Gram-negative. At least 15 % (w/v) NaCl was required for growth. The isolate grew at pH 6.5-9.0, with optimum growth at pH 7.0-7.5. Mg(2+) was required for growth. Polar lipids were C(20)C(20) derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, and phosphatidylglycerol sulfate and sulfated diglycosyl diether. The genomic DNA G+C content of strain 5.1(T) was 61.9 mol% (T(m)). Phylogenetic analysis based on comparison of 16S rRNA gene sequences revealed that strain 5.1(T) clustered with Halorubrum species. The results of DNA-DNA hybridization and biochemical tests allowed genotypic and phenotypic differentiation of strain 5.1(T) from other Halorubrum species. The name Halorubrum ezzemoulense sp. nov. (type strain 5.1(T)=CECT 7099(T)=DSM 17463(T)) is proposed.

Chromohalobacter nigrandesensis sp. nov., a moderately halophilic, Gram-negative bacterium isolated from Lake Tebenquiche on the Atacama Saltern, Chile.

A total of 52 strains of moderately halophilic bacteria isolated from hypersaline sediment of Lake Tebenquiche on the Atacama Saltern, Chile, were subjected to a taxonomic study. The morphological, physiological, biochemical and nutritional characteristics of the strains matched those described for the genus Chromohalobacter. Cells were Gram-negative, non-spore-forming, rod-shaped and motile. A black pigmentation was produced. One strain, designated LTS-4N(T), grew optimally at 32 degrees C. Growth occurred in media containing 0.5-25% (w/v) total salts; the optimum was 7.5% (w/v) total salts. The pH range for growth was 5-10. The G + C content of the DNA of strain LTS-4N(T) was 59.8 mol%. Analysis of 16S rRNA gene sequence similarity revealed that strain LTS-4N(T) was closely related to Chromohalobacter species; however, DNA-DNA hybridization of representative strain LTS-4N(T) failed to associate the strain with any species of the genus Chromohalobacter with validly published names. Therefore, the name Chromohalobacter nigrandesensis sp. nov. is proposed. The type strain is LTS-4N(T) (= CECT 5315T = DSM 14323T).

Biomineralization of carbonates by Halobacillus trueperi in solid and liquid media with different salinities.

We investigated the precipitation of carbonates by Halobacillus trueperi in both solid and liquid media at different salt concentrations and different magnesium/calcium ratios. H. trueperi precipitated at all assayed salt concentrations. When salt concentration increased, the quantity and the size of bioliths decreased and the time required increased. The precipitated minerals (determined by X-ray diffraction) were calcite, magnesium calcite and monohydrocalcite in variable proportions depending on the salinity and the physical state of the medium; the magnesium content of the magnesium calcites also varied with regard to the culture type. According to the saturation indices other minerals could also precipitate. Scanning electron microscopy showed that dominant morphologies of the bioliths were spherulitic with fibrous radiated interiors. We show that H. trueperi plays an active role in the precipitation of carbonates and we hypothesize about this process of biomineralization.

Halorubrum tebenquichense sp. nov., a novel halophilic archaeon isolated from the Atacama Saltern, Chile.

A novel extremely halophilic archaeon was isolated from Lake Tebenquiche, situated in the northern part of the Atacama Saltern, Chile. The cells of these micro-organisms were mostly irregularly disc-shaped. They grew in medium containing saturated concentrations of NaCl and did not require magnesium for optimal growth. The polar lipid composition revealed the presence of mannosyl-2-sulfate-(1-4)-glycosyl-archaeol, the main glycolipid of the genus Halorubrum, and two new glycolipids. The G+C content of the DNA was 63.2 mol%. Phylogenetic analysis of the 16S rRNA gene placed strain ALT6-92T within the Halorubrum cluster. The low DNA-DNA hybridization value justified classification in a new species for which the name Halorubrum tebenquichense sp. nov. is proposed. The type strain is ALT6-92T (= CECT 5317T = DSM 14210T).

Biologically active peptides in cyanobacteria

Las cianobacterias se encuentran en el medio natural tanto en aguas dulces como saladas. Ellas pueden desarrollarse en grandes masas formando "blooms" (florecimientos) en aguas dulces y saladas en diferentes partes del mundo, incluyendo América del Sur. Tales florecimientos, así como crecimientos axénicos de cianobacterias, pueden ser una rica fuente de péptidos lineales o cíclicos únicos, muchos de los cuales presentan actividad biológica. En el pasado la mayor atención ha sido puesta en las toxinas microcistina y nodulatoria. Estos péptidos ciclicos son hepatotoxinas que inhíben la proteína fosfatasa 1 y 2A, después de ingresar específicamente al hepatocito mediante la captación de las sales biliares. Sin embargo, en cianobacterias se están encontrando péptidos con otras actividades biológicas. No obstante, auque no se consideren tóxicos, estos péptidos tienen actividades biológicas tales como: una fuerte y específica inhibición de las proteasas (tripsina, quimo-tripsina, elastasa, trombina, plasmina y la enzima procesadora angiotensina), anticianobacterias, antialgas, antihongos, inmunosupresores y promotores de diferenciación celular. Ejemplos de péptidos cianobacteriales inhibidores de proteasas son las cianopeptolina. Las interacciones de microcistina/proteína fosfatasa y de cianopeptolina/proteasa, han sido bien estudiadas por difracción de rayos x en cocristales y la determinación de microcistina y de otros péptidos puede ser realizada por métodos químicos y biológicos. Ambas, microcistina y cianopeptolina han sido recientemente determinadas en blooms producidos en cuerpos de agua en Chile, utilizando cromatografía líquida de alta resolución (HPLC), espectrometría de masas (MALDI-TOF) (PSD), además de bioensayos de inhibición enzimática