This work is focused on a multidisciplinary study of 13 pottery fragments collected in the submerged archaeological site of Baia (Naples, Italy). Founded by the Romans in the 1st century B.C., this ...archaeological area represents one of the greatest evidences of Roman architecture and it includes ancient ruins whose structures range from maritime villas and imperial buildings. Several diagnostic tests were carried out in order to characterize the archaeological materials, their structure and properties, as well as the alteration and degradation products. Degradation forms in seawater imply not only a variation in the physico-mechanical and chemical properties of the material but also an aesthetic damage, due to superficial deposits, which can lead to the illegibility of the artefacts. In this context, it is crucial to determine to what extent these decay factors, mainly attributable to biological growth, could affect the durability of pottery and what are the effects of cleaning procedures. The work offers further elements to obtain new insights into the underwater cultural heritage field and in the function of ceramic matter, especially related to several applications in technology and in the adoption of strategies for suitable conservation procedures.
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•Multi-analytical study by microscopic techniques, XRD analysis, cleaning tests, colorimetric and ultrasound measurements•Characterization of archaeological materials, their structure, properties, alteration and degradation products•Final recognition of the extent of decay due to biological growth, affecting the durability of pottery•Evaluation of the effects of cleaning procedures•The data improve knowledge about preservation of ceramics from underwater and allow to set-up a protocol for their cleaning
Recently, bioprospecting in underexplored habitats has gained enhanced focus, since new taxa of marine actinobacteria can be found, and thus possible new metabolites. Actinobacteria are in the ...foreground due to their versatile production of secondary metabolites that present various biological activities, such as antibacterials, antitumorals and antifungals. Chilean marine ecosystems remain largely unexplored and may represent an important source for the discovery of bioactive compounds. Various culture conditions to enrich the growth of this phylum were used and 232 bacterial strains were isolated. Comparative analysis of the 16S rRNA gene sequences led to identifying genetic affiliations of 32 genera, belonging to 20 families. This study shows a remarkable culturable diversity of actinobacteria, associated to marine environments along Chile. Furthermore, 30 streptomycete strains were studied to establish their antibacterial activities against five model strains,
,
,
,
and
, demonstrating abilities to inhibit bacterial growth of Gram-positive bacteria. To gain insight into their metabolic profiles, crude extracts were submitted to liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis to assess the selection of streptomycete strains with potentials of producing novel bioactive metabolites. The combined approach allowed for the identification of three streptomycete strains to pursue further investigations. Our Chilean marine actinobacterial culture collection represents an important resource for the bioprospection of novel marine actinomycetes and its metabolites, evidencing their potential as producers of natural bioproducts.
Keratinases present promising biotechnological applications, due to their ability to degrade keratin. Streptomyces appears as one of the main sources of these enzymes, but complete genome sequences ...of keratinolytic bacteria are still limited. This article reports the complete genomes of three marine-derived streptomycetes that show different levels of feather keratin degradation, with high (strain G11C), low (strain CHD11), and no (strain Vc74B-19) keratinolytic activity. A multi-step bioinformatics approach is described to explore genes encoding putative keratinases in these genomes. Despite their differential keratinolytic activity, multiplatform annotation reveals similar quantities of ORFs encoding putative proteases in strains G11C, CHD11, and Vc74B-19. Comparative genomics classified these putative proteases into 140 orthologous groups and 17 unassigned orthogroup peptidases belonging to strain G11C. Similarity network analysis revealed three network communities of putative peptidases related to known keratinases of the peptidase families S01, S08, and M04. When combined with the prediction of cellular localization and phylogenetic reconstruction, seven putative keratinases from the highly keratinolytic strain Streptomyces sp. G11C are identified. To our knowledge, this is the first multi-step bioinformatics analysis that complements comparative genomics with phylogeny and cellular localization prediction, for the prediction of genes encoding putative keratinases in streptomycetes.
Marine-derived Actinobacteria are a source of a broad variety of secondary metabolites with diverse biological activities, such as antibiotics and antitumorals; many of which have been developed for ...clinical use. Rare Actinobacteria represent an untapped source of new bioactive compounds that have been scarcely recognized. In this study, rare Actinobacteria from marine sediments were isolated from the Valparaíso bay, Chile, and their potential to produce antibacterial compounds was evaluated. Different culture conditions and selective media that select the growth of Actinobacteria were used leading to the isolation of 68 bacterial strains. Comparative analysis of the 16S rRNA gene sequences led to identifying isolates that belong to the phylum Actinobacteria with genetic affiliations to 17 genera: Aeromicrobium, Agrococcus, Arthrobacter, Brachybacterium, Corynebacterium, Dietzia, Flaviflexus, Gordonia, Isoptericola, Janibacter, Microbacterium, Mycobacterium, Ornithinimicrobium, Pseudonocardia, Rhodococcus, Streptomyces, and Tessaracoccus. Also, one isolate could not be consistently classified and formed a novel phylogenetic branch related to the Nocardiopsaceae family. The antimicrobial activity of these isolates was evaluated, demonstrating the capability of specific novel isolates to inhibit the growth of Gram-positive and Gram-negative bacteria. In conclusion, this study shows a rich biodiversity of culturable Actinobacteria, associated to marine sediments from Valparaíso bay, highlighting novel rare Actinobacteria, and their potential for the production of biologically active compounds.
Marine actinobacteria are viewed as a promising source of enzymes with potential technological applications. They contribute to the turnover of complex biopolymers, such as pectin, lignocellulose, ...chitin, and keratin, being able to secrete a wide variety of extracellular enzymes. Among these, keratinases are a valuable alternative for recycling keratin-rich waste, which is generated in large quantities by the poultry industry. In this work, we explored the biocatalytic potential of 75 marine-derived actinobacterial strains, focusing mainly on the search for keratinases. A major part of the strains secreted industrially important enzymes, such as proteases, lipases, cellulases, amylases, and keratinases. Among these, we identified two streptomycete strains that presented great potential for recycling keratin wastes-
sp. CHA1 and
sp. G11C. Substrate concentration, incubation temperature, and, to a lesser extent, inoculum size were found to be important parameters that influenced the production of keratinolytic enzymes in both strains. In addition, proteomic analysis of culture broths from
sp. G11C on turkey feathers showed a high abundance and diversity of peptidases, belonging mainly to the serine and metallo-superfamilies. Two proteases from families S08 and M06 were highly expressed. These results contributed to elucidate the mechanism of keratin degradation mediated by streptomycetes.
sp. H-KF8 is an actinobacterial strain isolated from marine sediments of a Chilean Patagonian fjord. Morphological characterization together with antibacterial activity was assessed in various ...culture media, revealing a carbon-source dependent activity mainly against Gram-positive bacteria (
and
). Genome mining of this antibacterial-producing bacterium revealed the presence of 26 biosynthetic gene clusters (BGCs) for secondary metabolites, where among them, 81% have low similarities with known BGCs. In addition, a genomic search in
sp. H-KF8 unveiled the presence of a wide variety of genetic determinants related to heavy metal resistance (49 genes), oxidative stress (69 genes) and antibiotic resistance (97 genes). This study revealed that the marine-derived
sp. H-KF8 bacterium has the capability to tolerate a diverse set of heavy metals such as copper, cobalt, mercury, chromate and nickel; as well as the highly toxic tellurite, a feature first time described for
. In addition,
sp. H-KF8 possesses a major resistance towards oxidative stress, in comparison to the soil reference strain
A3(2). Moreover,
sp. H-KF8 showed resistance to 88% of the antibiotics tested, indicating overall, a strong response to several abiotic stressors. The combination of these biological traits confirms the metabolic versatility of
sp. H-KF8, a genetically well-prepared microorganism with the ability to confront the dynamics of the fjord-unique marine environment.
This study examines the deterioration of geomaterials used throughout history that today may be found lying on the ocean floor. Submerged archaeological sites including cargoes from shipwrecks or ...ancient city ruins have been a topic of interest from a perspective of in situ musealization, as a way of making underwater cultural heritage accessible to the public. In an experimental study conducted at an underwater archaeological site in the Bay of Cádiz (SW Spain), we subjected two types of marble (Carrara and Macael) to three conditions to which submerged archaeological objects are often exposed: full exposure to the water column, natural processes of burial and unearthing, or permanent burial. After an 18-month study period, the factor found to mostly affect these materials was their biological colonization. This factor was assessed by estimating total surface biocover and the rate of surface biocolonization, and also through the identification of skeletons and associated alteration forms by light microscopy, and scanning electron microscopy (SEM). Biofouling and bioerosion were the main causes of biodeterioration and dependent on the position of the marble specimens in the seawater. The response of both materials was similar, though dolomite crystals in the Carrara marble acted as a protective barrier against actively penetrating microorganisms. These investigations have allowed the study of tracers left by epilithic encrusting organisms and endolithic bioeroders on marbles intentionally exposed to seawater, providing new insights to the understanding of the biodeterioration processes occurring in cultural heritage stones, with significant implications when they are part of underwater archaeological remains.
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•The biodeterioration of Macael and Carrara marbles was examined in a mid-term underwater test.•Three conditions were used to simulate those of stones on the seabed.•Calcareous deposits and microboring patterns were the main biodecay effects.•Buried and water exposures derived into the least and the greatest biocolonization.•Understanding biodeterioration helps to protect underwater cultural heritage.
An alkaliphilic actinobacterium, designated VN6-2
, was isolated from marine sediment collected from Valparaíso Bay, Chile. Strain VN6-2
formed yellowish-white branched substrate mycelium without ...fragmentation. Aerial mycelium was well developed, forming wavy or spiral spore chains. Strain VN6-2
exhibited a 16S rRNA gene sequence similarity of 93.9 % to
CXB832
, 93.7 % to
14-Be-013
, and 93.7 % to
14-Be-013
. Genome sequencing revealed a genome size of 5.9 Mb and an
G+C content of 69.3 mol%. Both of the phylogenetic analyses based on 16S rRNA gene sequences and the up-to-date bacterial core gene sequences revealed that strain VN6-2
formed a distinct monophyletic clade within the family
. Chemotaxonomic assessment of strain VN6-2
showed that the major fatty acids were iso-C
, anteiso-C
and 10-methyl-C
, and the predominant respiratory quinones were MK-9, MK-9(H
) and MK-9(H
). Whole-cell hydrolysates contained
-diaminopimelic acid as the cell-wall diamino acid, and ribose and xylose as the diagnostic sugars. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, aminophospholipids, glycolipid and phospholipid. Based on the results of this polyphasic study, a novel genus,
gen. nov., is proposed within the family
and the type species
gen. nov., sp. nov. The type strain is VN6-2
(CECT 30026
, CCUG 66258
). On the basis of the phylogenetic results herein, we also propose that
are later heterotypic synonyms of
and
, respectively, for which emended descriptions are given.
This study determined the carriage rates and antimicrobial resistance (AMR) genes of enterococci from nasotracheal samples of three healthy animal species and in-contact humans. Nasal samples were ...collected from 27 dog-owning households (34 dogs, 41 humans) and 4 pig-farms (40 pigs, 10 pig-farmers), and they were processed for enterococci recovery (MALDI-TOF–MS identification). Also, a collection of 144 enterococci previously recovered of tracheal/nasal samples from 87 white stork nestlings were characterized. The AMR phenotypes were determined in all enterococci and AMR genes were studied by PCR/sequencing. MultiLocus-Sequence-Typing was performed for selected isolates. About 72.5% and 60% of the pigs and pig-farmers, and 29.4% and 4.9%, of healthy dogs and owners were enterococci nasal carriers, respectively. In storks, 43.5% of tracheal and 69.2% of nasal samples had enterococci carriages. Enterococci carrying multidrug-resistance phenotype was identified in 72.5%/40.0%/50.0%/23.5%/1.1% of pigs/pig-farmers/dogs/dogs’ owners/storks, respectively. Of special relevance was the detection of linezolid-resistant enterococci (LRE) in (a) 33.3% of pigs (
E. faecalis
-carrying
optrA
and/or
cfrD
of ST59, ST330 or ST474 lineages;
E. casseliflavus
-carrying
optrA
and
cfrD
); (b) 10% of pig farmers (
E. faecalis
-ST330-carrying
optrA
); (c) 2.9% of dogs (
E. faecalis-
ST585-carrying
optrA
); and (d) 1.7% of storks (
E. faecium
-ST1736-carrying
poxtA
). The
fexA
gene was found in all
optrA
-positive
E. faecalis
and
E. casseliflavus
isolates, while
fexB
was detected in the
poxtA-
positive
E. faecium
isolate. The enterococci diversity and AMR rates from the four hosts reflect differences in antimicrobial selection pressure. The detection of LRE carrying acquired and transferable genes in all the hosts emphasizes the need to monitor LRE using a One-Health approach.
B. xenovorans LB400 is a model bacterium for the study of the metabolism of aromatic compounds. The aim of this study was the genomic and functional characterization of a non-ribosomal peptide ...synthetase containing gene cluster that encodes a siderophore in B. xenovorans LB400. The mba gene cluster from strain LB400 encodes proteins involved in the biosynthesis and transport of a hydroxamate-type siderophore. Strain LB400 has a unique mba gene organization, although mba gene clusters have been observed in diverse Burkholderiales. Bioinformatic analysis revealed the presence of promoters in the mba gene cluster that strongly suggest regulation by the ferric uptake regulator protein (Fur) and by the alternative RNA polymerase extracytoplasmic function sigma factor MbaF. Reverse transcriptase PCR analyses showed the expression of iron-regulated transcriptional units mbaFGHIJKL, mbaN, mbaABCE, mbaO, mbaP and mbaD genes under iron limitation. Chrome azurol S (CAS) assay strongly suggests that strain LB400 synthesized a siderophore under iron limitation. Mass spectrometry ESI-MS and MALDI-TOF-MS analyses revealed that the siderophore is a non-ribosomal peptide, and forms an iron complex with a molecular mass of 676 Da. Based on bioinformatic prediction, CAS assay and MS analyses, we propose that the siderophore is L-Nδ-hydroxy-Nδ-formylOrn-D-β-hydroxyAsp-L-Ser-L-Nδ-hydroxy-Nδ-formylOrn-1,4-diaminobutane that is closely related to malleobactin-type siderophores reported in B. thailandensis.
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