Impact of irrigation with fish-processing effluents on nitrification and ammonia-oxidizer abundances in Patagonian arid soils.

This study aimed to evaluate the short-term effects of irrigation with diluted fish-processing effluents on soil pH, electrical conductivity, nitrification rate and abundance of ammonia oxidizers. To accomplish that, we constructed microcosms of soil from an undisturbed arid ecosystem of Patagonia, and irrigated them for 2 months with diluted effluents from a fish-processing factory or with water as control. In the initial soil sample, and along the experiment, we determined soil pH, electrical conductivity, and the concentration of inorganic nitrogen forms, which we used to calculate the net nitrification rate. We further estimated the abundances of ammonia-oxidizing archaea and bacteria in the initial soil sample and at the end of the experiment, by qPCR of amoA genes. Soil pH decreased and electrical conductivity increased in both irrigation treatments, although the effect was higher in effluent-irrigated microcosms. Soil nitrate + nitrite concentration, and thus the nitrification rate, was higher in effluent than in water-irrigated microcosms. The abundance of archaeal amoA genes was higher under effluent than water-irrigation, but that of bacterial amoA genes did not vary significantly between treatments. Neither ammonia-oxidizing archaea nor bacteria were influenced by the changes in soil pH and electrical conductivity induced by effluent irrigation.

Proteomic analysis and optimized production of Alkalihalobacillus patagoniensis PAT 05T extracellular proteases.

Extracellular proteolytic extracts from the haloalkalitolerant strain Alkalihalobacillus patagoniensis PAT 05T have proved highly efficient to reduce wool felting, as part of an ecofriendly treatment suitable for organic wool. In the present study, we identified the extracellular proteases produced by PAT 05T and we optimized its growth conditions for protease production through statistical methods. A total of 191 proteins were identified in PAT 05T culture supernatants through mass spectrometry analysis. Three of the 6 detected extracellular proteases belonged to the serine-endopeptidase family S8 (EC 3.4.21); two of them showed 86.3 and 67.9% identity with an alkaline protease from Bacillus alcalophilus and another one showed 50.4% identity with Bacillopeptidase F. The other 3 proteases exhibited 55.3, 49.4 and 61.1% identity with D-alanyl-D-alanine carboxypeptidase DacF, D-alanyl-D-alanine carboxypeptidase DacC and endopeptidase LytE, respectively. Using a Fractional Factorial Design followed by a Central Composite Design optimization, a twofold increase in protease production was reached. NaCl concentration was the most influential factor on protease production. The usefulness of PAT 05T extracellular proteolytic extracts to reduce wool felting was possible associated with the activity of the serine-endopeptidases closely related to highly alkaline keratinolytic proteases. The other identified proteases could cooperate, improving protein hydrolysis. This study provided valuable information for the exploitation of PAT 05T proteases which have potential for the valorization of organic wool as well as for other industrial applications.

Newly isolated Bacillus sp. G51 from Patagonian wool produces an enzyme combination suitable for felt-resist treatments of organic wool.

Bacteria from Patagonian Merino wool were isolated to assess their wool-keratinolytic activity and potential for felt-resist treatments. Strains from Bacillus, Exiguobacterium, Deinococcus, and Micrococcus produced wool-degrading enzymes. Bacillus sp. G51 showed the highest wool-keratinolytic activity. LC-MS/MS analysis revealed that G51 secreted two serine proteases belonging to the peptidase family S8 (MEROPS) and a metalloprotease associated with Bacillolysin, along with other enzymes (γ-glutamyltranspeptidase and dihydrolipoyl dehydrogenases) that could be involved in reduction of keratin disulfide bonds. Optimum pH and temperature of G51 proteolytic activity were 9 and 60 °C, respectively. More than 80% of activity was retained in H2O2, Triton X-100, Tween 20, Lipocol OXO650, Teridol B, and ß-mercaptoethanol. Treatment of wool top with G51 enzyme extract caused a decrease in wool felting tendency without significant weight loss (<1.5%). Sparse work has so far been performed to investigate suitable keratinases for the organic wool sector. This eco-friendly treatment based on a new enzyme combination produced by a wild bacterium has potential for meeting the demands of organic wool processing which bans the use of hazardous chemicals and genetic engineering.

Potential aquaculture probiont Lactococcus lactis TW34 produces nisin Z and inhibits the fish pathogen Lactococcus garvieae.

Bacteriocin-producing Lactococcus lactis TW34 was isolated from marine fish. TW34 bacteriocin inhibited the growth of the fish pathogen Lactococcus garvieae at 5 AU/ml (minimum inhibitory concentration), whereas the minimum bactericidal concentration was 10 AU/ml. Addition of TW34 bacteriocin to L. garvieae cultures resulted in a decrease of six orders of magnitude of viable cells counts demonstrating a bactericidal mode of action. The direct detection of the bacteriocin activity by Tricine-SDS-PAGE showed an active peptide with a molecular mass ca. 4.5 kDa. The analysis by MALDI-TOF-MS detected a strong signal at m/z 2,351.2 that corresponded to the nisin leader peptide mass without the initiating methionine, whose sequence STKDFNLDLVSVSKKDSGASPR was confirmed by MS/MS. Sequence analysis of nisin structural gene confirmed that L. lactis TW34 was a nisin Z producer. This nisin Z-producing strain with probiotic properties might be considered as an alternative in the prevention of lactococcosis, a global disease in aquaculture systems.

Antibacterial properties of water-soluble gold(I) N-heterocyclic carbene complexes.

The antibacterial properties of water-soluble gold(I) complexes [1-methyl-3-(3-sulfonatopropyl)imidazol-2-ylidene]gold(I) chloride (C1), [1-mesityl-3-(3-sulfonatopropyl)imidazol-2-ylidene]gold(I) chloride (C2), [1-(2,6-diisopropylphenyl)-3-(3-sulfonatopropyl)imidazol-2-ylidene]gold(I) chloride (C3) and [1,3-bis(2,6-diisopropyl-4-sodiumsulfonatophenyl)imidazol-2-ylidene]gold(I) chloride (C4) and the respective ligands were assessed by agar diffusion and broth macrodilution methods against Gram-positives Staphylococcus aureus, Enterococcus faecalis and Micrococcus luteus and the Gram-negative bacteria Yersinia ruckeri, Pseudomonas aeruginosa and Escherichia coli. Viability after treatments was determined by direct plate count. The bactericidal activity displayed by C1 and C3 was comparable to that of AgNO3.

Bioprospection of marine microorganisms: potential and challenges for Argentina.

The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the research topics and the interactions among Argentinean laboratories, by analyzing current articles published on biotechnology-related marine microbiology by researchers of this country. In addition, we identify the challenges and opportunities for Argentina to take advantage of the genetic potential of its marine microorganisms. Finally, we suggest possible actions that could improve the development of this research field, as well as the utilization of this knowledge to solve societal needs.

Bioprospection of marine microorganisms: potential and challenges for Argentina / Bioprospección de microorganismos marinos: potencialidades y desafíos para Argentina

The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the research topics and the interactions among Argentinean laboratories, by analyzing current articles published on biotechnology-related marine microbiology by researchers of this country. In addition, we identify the challenges and opportunities for Argentina to take advantage of the genetic potential of its marine microorganisms. Finally, we suggest possible actions that could improve the development of this research field, as well as the utilization of this knowledge to solve societal needs.

El medio ambiente marino de la Argentina tiene una notable extensión, como así también una alta productividad biológica y biodiversidad de macro y microorganismos. A pesar de presentar un gran potencial para aplicaciones biotecnológicas, los microorganismos que habitan estos ecosistemas permanecen mayormente inexplorados y sus propiedades aún no explotadas. En este trabajo de revisión, estudiamos los temas de investigación y las interacciones entre grupos de investigación argentinos, por medio del análisis de los artículos publicados hasta el momento en temáticas relacionadas con la aplicación biotecnológica de microorganismos marinos. Además, identificamos los desafíos y las oportunidades para que la Argentina tome ventaja del potencial genético de sus microorganismos marinos. Por último, sugerimos posibles acciones que podrían mejorar el desarrollo de este campo de estudio, como así también la utilización de este conocimiento para resolver las necesidades de la sociedad.

Bioprospection of marine microorganisms: potential and challenges for Argentina / Bioprospección de microorganismos marinos: potencialidades y desafíos para Argentina

The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the research topics and the interactions among Argentinean laboratories, by analyzing current articles published on biotechnology-related marine microbiology by researchers of this country. In addition, we identify the challenges and opportunities for Argentina to take advantage of the genetic potential of its marine microorganisms. Finally, we suggest possible actions that could improve the development of this research field, as well as the utilization of this knowledge to solve societal needs.(AU)

El medio ambiente marino de la Argentina tiene una notable extensión, como así también una alta productividad biológica y biodiversidad de macro y microorganismos. A pesar de presentar un gran potencial para aplicaciones biotecnológicas, los microorganismos que habitan estos ecosistemas permanecen mayormente inexplorados y sus propiedades aún no explotadas. En este trabajo de revisión, estudiamos los temas de investigación y las interacciones entre grupos de investigación argentinos, por medio del análisis de los artículos publicados hasta el momento en temáticas relacionadas con la aplicación biotecnológica de microorganismos marinos. Además, identificamos los desafíos y las oportunidades para que la Argentina tome ventaja del potencial genético de sus microorganismos marinos. Por último, sugerimos posibles acciones que podrían mejorar el desarrollo de este campo de estudio, como así también la utilización de este conocimiento para resolver las necesidades de la sociedad.(AU)

Bioprospection of marine microorganisms: biotechnological applications and methods.

Environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. In particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. This has resulted in novel and more complex approaches for the screening of molecules and activities of biotechnological interest in these environments. In this review, we explore the different partially overlapping biotechnological fields that make use of microorganisms and we describe the different marine habitats that are particularly attractive for bioprospection. In addition, we review the methodological approaches currently used for microbial bioprospection, from the traditional cultivation techniques to state of the art metagenomic approaches, with emphasis in the marine environment.

Bioprospection of marine microorganisms: biotechnological applications and methods

Bioprospección de microorganismos marinos: aplicaciones biotecnológicas y métodos. Los microorganismos ambientales constituyen una reserva prácticamente inagotable de diversidad genética, acumulada durante millones de años de evolución adaptativa a varias presiones selectivas. En particular, la magnitud de la biodiversidad microbiana en hábitats marinos parece crecer al emerger nuevas técnicas para medirla. Como resultado, se han comenzado a utilizar enfoques novedosos y más complejos para la búsqueda de moléculas y actividades de interés biotecnológico en estos ambientes. En este artículo de revisión, nosotros exploramos los diferentes campos de la biotecnología que utilizan microorganismos, los cuales se superponen parcialmente, y describimos los diferentes hábitats marinos que resultan particularmente atractivos para la bioprospección. Además, revisamos los enfoques metodológicos actualmente utilizados para la bioprospección microbiana, desde las técnicas de cultivo tradicionales hasta modernos enfoques metagenómicos, con énfasis en el medio ambiente marino.

Environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. In particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. This has resulted in novel and more complex approaches for the screening of molecules and activities of biotechnological interest in these environments. In this review, we explore the different partially overlapping biotechnological fields that make use of microorganisms and we describe the different marine habitats that are particularly attractive for bioprospection. In addition, we review the methodological approaches currently used for microbial bioprospection, from the traditional cultivation techniques to state of the art metagenomic approaches, with emphasis in the marine environment.

Bioprospection of marine microorganisms: biotechnological applications and methods

Bioprospección de microorganismos marinos: aplicaciones biotecnológicas y métodos. Los microorganismos ambientales constituyen una reserva prácticamente inagotable de diversidad genética, acumulada durante millones de años de evolución adaptativa a varias presiones selectivas. En particular, la magnitud de la biodiversidad microbiana en hábitats marinos parece crecer al emerger nuevas técnicas para medirla. Como resultado, se han comenzado a utilizar enfoques novedosos y más complejos para la búsqueda de moléculas y actividades de interés biotecnológico en estos ambientes. En este artículo de revisión, nosotros exploramos los diferentes campos de la biotecnología que utilizan microorganismos, los cuales se superponen parcialmente, y describimos los diferentes hábitats marinos que resultan particularmente atractivos para la bioprospección. Además, revisamos los enfoques metodológicos actualmente utilizados para la bioprospección microbiana, desde las técnicas de cultivo tradicionales hasta modernos enfoques metagenómicos, con énfasis en el medio ambiente marino.(AU)

Environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. In particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. This has resulted in novel and more complex approaches for the screening of molecules and activities of biotechnological interest in these environments. In this review, we explore the different partially overlapping biotechnological fields that make use of microorganisms and we describe the different marine habitats that are particularly attractive for bioprospection. In addition, we review the methodological approaches currently used for microbial bioprospection, from the traditional cultivation techniques to state of the art metagenomic approaches, with emphasis in the marine environment.(AU)

Bioprospection of marine microorganisms: biotechnological applications and methods

Bioprospección de microorganismos marinos: aplicaciones biotecnológicas y métodos. Los microorganismos ambientales constituyen una reserva prácticamente inagotable de diversidad genética, acumulada durante millones de años de evolución adaptativa a varias presiones selectivas. En particular, la magnitud de la biodiversidad microbiana en hábitats marinos parece crecer al emerger nuevas técnicas para medirla. Como resultado, se han comenzado a utilizar enfoques novedosos y más complejos para la búsqueda de moléculas y actividades de interés biotecnológico en estos ambientes. En este artículo de revisión, nosotros exploramos los diferentes campos de la biotecnología que utilizan microorganismos, los cuales se superponen parcialmente, y describimos los diferentes hábitats marinos que resultan particularmente atractivos para la bioprospección. Además, revisamos los enfoques metodológicos actualmente utilizados para la bioprospección microbiana, desde las técnicas de cultivo tradicionales hasta modernos enfoques metagenómicos, con énfasis en el medio ambiente marino.(AU)

Environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. In particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. This has resulted in novel and more complex approaches for the screening of molecules and activities of biotechnological interest in these environments. In this review, we explore the different partially overlapping biotechnological fields that make use of microorganisms and we describe the different marine habitats that are particularly attractive for bioprospection. In addition, we review the methodological approaches currently used for microbial bioprospection, from the traditional cultivation techniques to state of the art metagenomic approaches, with emphasis in the marine environment.(AU)

The occurrence of Shiga toxin-producing Escherichia coli in bathing water of the Sierra de la Ventana region, Buenos Aires Province, Argentina.

The region of Sierra de la Ventana is located in the southwest of Buenos Aires Province, Argentina. Traditionally, this area has been devoted to livestock and agriculture, but tourism has had a significant development in recent years. In the region, there are many rivers and streams that are used for swimming and bathing. A survey of the occurrence of Shiga toxin-producing Escherichia coli (STEC) in these waters was conducted, and the microbiological quality of rivers and streams was investigated. No E. coli O157 was recovered by immunomagnetic separation. Nevertheless, the Shiga toxin gene, exclusively stx2 genotype, was detected in four non-O157 E. coli strains. Two STEC strains carried eae factor, but none of them harbored the EHEC-hlyA gene. Three of the STEC isolates belonged to samples obtained in the warm months, and one to the winter sampling. In the sample sites where STEC strains were isolated the counts of E. coli/100 ml exceeded or were close to the limit recommended by the United States Environmental Protection Agency for bathing water. The relationship observed between the rainy season and E. coli counts suggests that among the main causes for the hygienic indicator increase is the runoff of manure deposited on soils that may also induce the entrance of pathogens into the aquatic environment. This research, the first reporting STEC isolation from recreational waters in this area, revealed that streams and rivers from a beef-producing area of Argentina are a reservoir of STEC strains.

Characterization of indigenous Rhodococcus sp. 602, a strain able to accumulate triacylglycerides from naphthyl compounds under nitrogen-starved conditions.

An indigenous bacterium (strain 602) isolated in this study from a polluted soil sample collected in Patagonia (Argentina) was investigated in relation to its metabolic responses under unbalanced growth conditions. This strain was identified as Rhodococcus sp. by molecular analyses. Strain 602 showed the ability to degrade a wide range of compounds and to synthesize triacylglycerols under nitrogen-limiting conditions. Cells were also able to accumulate triacylglycerols during cultivation on naphthalene and naphthyl-1-dodecanoate. Triacylglycerols produced by resting cells in the presence of naphthyl-1-dodecanoate contained only short-chain length fatty acids (from C(8) to C(12)), suggesting an initial attack of the substrate by an esterase releasing 1-naphthol and dodecanoic acid, which was subsequently degraded by beta-oxidation. On the other hand, naphthalene seemed to be degraded by a mono-oxygenase yielding 1-naphthol, which was then transformed to 4-hydroxy-1-tetralone and to other possible metabolic intermediates. On the basis of the results obtained, a pathway involved in the metabolism of both aromatic compounds under nitrogen starvation by strain 602 is proposed. The results also demonstrated that Rhodococcus sp. 602 maintains its metabolic activity even in the absence of a nitrogen source. Intracellular triacylglycerols may help cells to maintain their catabolic activities under these growth-restricting conditions.

Isolation and characterization of biosurfactant-producing Alcanivorax strains: hydrocarbon accession strategies and alkane hydroxylase gene analysis.

Biosurfactant-producing bacteria belonging to the genera Alcanivorax, Cobetia and Halomonas were isolated from marine sediments with a history of hydrocarbon exposure (Aristizábal and Gravina Peninsulas, Argentina). Two Alcanivorax isolates were found to form naturally occurring consortia with strains closely related to Pseudomonas putida and Microbacterium esteraromaticum. Alkane hydroxylase gene analysis in these two Alcanivorax strains resulted in the identification of two novel alkB genes, showing 86% and 60% deduced amino acid sequence identity with those of Alcanivorax sp. A-11-3 and Alcanivorax dieselolei P40, respectively. In addition, a gene homologous to alkB2 from Alcanivorax borkumensis was present in one of the strains. The consortium formed by this strain, Alcanivorax sp. PA2 (98.9% 16S rRNA gene sequence identity with A. borkumensis SK2(T)) and P. putida PA1 was characterized in detail. These strains form cell aggregates when growing as mixed culture, though only PA2 was responsible for biosurfactant activity. During exponential growth phase of PA2, cells showed high hydrophobicity and adherence to hydrocarbon droplets. Biosurfactant production was only detectable at late growth and stationary phases, suggesting that it is not involved in initiating oil degradation and that direct interfacial adhesion is the main hydrocarbon accession mode of PA2. This strain could be useful for biotechnological applications due to its biosurfactant production, catabolic and aggregation properties.

Diversity and enzyme properties of protease-producing bacteria isolated from sub-Antarctic sediments of Isla de Los Estados, Argentina.

Protease-producing bacteria isolated from sub-Antarctic marine sediments of Isla de Los Estados (Argentina) were characterized, and the thermal inactivation kinetics of their extracellular proteases compared. Isolates were affiliated with the genera Pseudoalteromonas, Shewanella, Colwellia, Planococcus, and a strain to the family Flavobacteriaceae. Colwellia strains were moderate psychrophiles (optimal growth at about 15 degrees C, maximum growth temperature at around 25 degrees C). 16S rRNA phylogenetic analysis revealed that these strains and Colwellia aestuarii form a distinct lineage within the genus. The remaining isolates were psychrotolerant and grew optimally between 20 and 25 degrees C; two of them represent potentially novel species or genus (16S rRNA < 97% sequence similarity). The thermostability of the extracellular proteases produced by the isolates was analysed, and the inactivation rate constant (k (in)), the activation energy (Ea(in)) and the activation Gibbs free energy of thermal inactivation (Delta G( * ) (in)) determined. Delta G( * ) (in), calculated at 30 degrees C, varied between 97 and 124 kJ/mol. Colwellia enzyme extracts presented the highest thermosensitivity, while the most thermostable protease activity was shown by Shewanella spp. These results demonstrated that the stability to temperature of these enzymes varies considerably among the isolates, suggesting important variations in the thermal properties of the proteases that can coexist in this environment.