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Dimethylsulfoniopropionate (DMSP) is a vital sulfur-containing compound with worldwide significance, serving as the primary precursor for dimethyl sulfide (DMS), a volatile sulfur compound that plays a role in atmospheric chemistry and influences the Earth's climate on a global scale. The study investigated the ability of four bacterial strains, namely Acidimangrovimonas sediminis MS2-2 (MS2-2), Hartmannibacter diazotrophicus E18T (E18T), Rhizobium lusitanum 22705 (22705), and Nitrospirillum iridis DSM22198 (DSM22198), to produce and degrade DMSP. These strains were assessed for their DMSP synthesis ability with the mmtN linked to non-ribosomal peptide synthase (NRPS) gene. The results showed that MS2-2, and E18T bacteria, which contained the mmtN but not linked to an NRPS gene, increased DMSP production with increasing salinity. The highest production of DMSP was achieved at 25 PSU when either methionine was added or low nitrogen conditions were present, yielding 1656.03 ± 41.04 and 265.59 ± 9.17 nmol/mg protein, respectively, and subsequently under the conditions of methionine addition or low nitrogen, both strains reached their maximum DMSP production at 25 PSU. Furthermore, the strains MS2-2, E18T, and 22705 with the mmtN gene but not linked to an NRPS gene were found to be involved in DMS production. This research contributes to the understanding of the genes involved in DMSP biosynthesis in bacteria that produce DMSP. [ABSTRACT FROM AUTHOR]

Abstract Background Staphylococcus argenteus is a new specie positive coagulase staphylococci. We investigate the presence of S. argenteus in isolates previously classified as S. aureus, obtained from the milk of cows with mastitis in Brazil. Results Among 856 S. aureus tested in chocolate agar, tryptone soya agar and salt egg yolk agar, white or colorless colonies were observed in 185 (21.6%) isolates. Regarding the ctrOPQMN operon, 111 (60%) presented the complete cluster. Despite some missing genes in this cluster, the remaining strains (74) were confirmed as S. aureus using the nrps gene. Conclusions As far as we know, this is the first review of S. aureus collection in Brazil and S. argenteus does not appear to be a significant problem in Brazilian herds.

Background: Staphylococcus argenteus is a new specie positive coagulase staphylococci. We investigate the presence of S. argenteus in isolates previously classified as S. aureus, obtained from the milk of cows with mastitis in Brazil. Results: Among 856 S. aureus tested in chocolate agar, tryptone soya agar and salt egg yolk agar, white or colorless colonies were observed in 185 (21.6%) isolates. Regarding the ctrOPQMN operon, 111 (60%) presented the complete cluster. Despite some missing genes in this cluster, the remaining strains (74) were confirmed as S. aureus using the nrps gene. Conclusions: As far as we know, this is the first review of S. aureus collection in Brazil and S. argenteus does not appear to be a significant problem in Brazilian herds. [ABSTRACT FROM AUTHOR]

Aims: Isolating culturable bacteria associated with sea cucumber (Apostichopus japonicus) and investigating their potential bioactivities are important approaches to discover natural marine products. Methods and Results: A total of 161 isolates were obtained from sea cucumber collected along the Weihai coast of the North Yellow Sea, China. Identification and phylogenetic analysis of 61 isolates were conducted by 16S rRNA gene sequencing. The isolates belonged to 13 genera from 10 families in three phyla, including Firmicutes, Actinobacteria and Proteobacteria. The antimicrobial activities of all strains were determined using six indicator strains. Of the 161 isolates, 93 showed antibacterial activities against at least one of the indicator strains. The 26 strains with the strongest inhibitory effects were selected for screening the biosynthetic gene clusters of polyketide synthase (PKS‐I, ‐II) and nonribosomal peptide synthetase (NRPS). Phylogenetic trees based on the amino acid sequences of the PKS or NRPS genes were constructed. Eleven strains with PKS genes and four strains with NRPS genes were detected. Conclusions: The data reveal the diversity of culturable bacteria associated with A. japonicus. Most strains showed broad‐spectrum antimicrobial activities, and some strains with antimicrobial activities possessed PKS and NRPS genes. Significance and Impact of the Study: The results suggest that culturable bacteria associated with A. japonicus may act as a promising source of bioactive substances. [ABSTRACT FROM AUTHOR]

Tetrodotoxins (TTXs), potent neurotoxins, have become an increasing concern in Europe in recent decades, especially because of their presence in mollusks. The European Food Safety Authority published a Scientific Opinion setting a recommended threshold for TTX in mollusks of 44 µg equivalent kg−1 and calling all member states to contribute to an effort to gather data in order to produce a more exhaustive risk assessment. The objective of this work was to assess TTX levels in wild and farmed mussels (Mytilus galloprovincialis) harvested in 2018–2019 along the coastal area of the Marche region in the Central Adriatic Sea (Italy). The presence of Vibrio spp. carrying the non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes, which are suspected to be involved in TTX biosynthesis, was also investigated. Out of 158 mussel samples analyzed by hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS), 11 (7%) contained the toxins at detectable levels (8–26 µg kg−1) and 3 (2%) contained levels above the EFSA safety threshold (61–76 µg kg−1). Contaminated mussels were all harvested from natural beds in spring or summer. Of the 2019 samples, 70% of them contained V. alginolyticus strains with the NRPS and/or PKS genes. None of the strains containing NRPS and/or PKS genes showed detectable levels of TTXs. TTXs in mussels are not yet a threat in the Marche region nor in Europe, but further investigations are surely needed.

The object of this study was to find and characterise streptomycete isolates with antimicrobial activity accomplished by the agar plug method against phytopathogenic species. The test-microorganisms were selected according to their importance in agriculture. All of them belong to phytopathogenic species which reduce yields of agriculturally important plants worldwide. A total number of four phytopathogenic bacteria (Xanthomonas campestris (CCM 22), Pseudomonas syringae (CCM 2868), Erwinia amylovora (CCM 1114), Clavibacter michiganensis subsp. sepedonicus (CCM 7014)) and four phytopathogenic fungi (Botrytis cinerea, Fusarium poae, Alternaria tenuissima, Alternaria arborescens) were used for this experiment. Overall twenty streptomycete isolates showed antimicrobial activity against at least two of the test-microorganisms. These active isolates were subsequently characterized. Streptomycete isolates were observed for morphological characteristics, such as morphology and colour of aerial and substrate mycelium, colour of diffusible pigments, production of melanoid pigments on peptone-yeast extract iron agar and sporophore and spore chain morphology following the International Streptomyces Project. Genes coding polyketide synthase (PKS-I) and nonribosomal peptide synthetase (NRPS), which are considered to responsible for the synthesis of large number of biologically active compounds, like antibiotics and antifungals, that are produced by Streptomyces species largely, were screened. The occurrence of these genes in the genome of our isolates was in accordance with results from antimicrobial activity analysis. Classification to genus Streptomyces were confirmed by DNA sequencing. [ABSTRACT FROM AUTHOR]

Tetrodotoxins (TTXs), potent neurotoxins, have become an increasing concern in Europe in recent decades, especially because of their presence in mollusks. The European Food Safety Authority published a Scientific Opinion setting a recommended threshold for TTX in mollusks of 44 µg equivalent kg−1 and calling all member states to contribute to an effort to gather data in order to produce a more exhaustive risk assessment. The objective of this work was to assess TTX levels in wild and farmed mussels (Mytilus galloprovincialis) harvested in 2018–2019 along the coastal area of the Marche region in the Central Adriatic Sea (Italy). The presence of Vibrio spp. carrying the non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes, which are suspected to be involved in TTX biosynthesis, was also investigated. Out of 158 mussel samples analyzed by hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS), 11 (7%) contained the toxins at detectable levels (8–26 µg kg−1) and 3 (2%) contained levels above the EFSA safety threshold (61–76 µg kg−1). Contaminated mussels were all harvested from natural beds in spring or summer. Of the 2019 samples, 70% of them contained V. alginolyticus strains with the NRPS and/or PKS genes. None of the strains containing NRPS and/or PKS genes showed detectable levels of TTXs. TTXs in mussels are not yet a threat in the Marche region nor in Europe, but further investigations are surely needed. [ABSTRACT FROM AUTHOR]