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PubMed1975

Collagenolytic activity of some marine bacteria.

Reconstituted, acid-extracted collagen was used to prepare a medium to screen proteolytic marine bacteria for their ability to elaborate collagenolytic enzymes. The medium was resistant to solubilization by trypsin, hyaluronidase, chondroitinase ABC, and various marine proteinases, but was readily hydrolyzed by commercial Clostridium collagenases. Eighty-seven marine isolates collected in the vicinity of Bermuda, Oahu (Hawaii), and Stone Harbor and Cape May, N. J., were screened. Approximately 44 per cent of the isolates were capable of elaborating enzymes that hydrolyzed reconstituted collagen gels. Several cultures produced collagenolytic enzymes only when grown in the presence of collagen or degradation products of collagen, and with very few exceptions the presence of collagen in the medium greatly enhanced collagenolytic enzyme production. The enzymes from a collagenolytic Bermuda marine isolate were studied in more detail to illustrate that the enzymes capable of hydrolyzing reconstituted collagen were separable from nonspecific proteinases by zone electrophoresis and that these enzymes were true collagenases by virtue of their ability to hydrolyze native bovine Achilles'tendon obtained from three different sources.

Animals↗
PubMed2024

A comparative genomic study of a hydrocarbon-degrading marine bacterial consortium.

Ocean oil pollution has a large impact on the environment and the health of living organisms. Bioremediation cleaning strategies are promising eco-friendly alternatives for tackling this problem. Previously, we designed and reported a hydrocarbon (HC) degrading microbial consortium of four marine strains belonging to the species Alloalcanivorax xenomutans, Halopseudomonas aestusnigri, Paenarthrobacter sp., and Pseudomonas aeruginosa. However, the knowledge about the metabolic potential of this bacterial consortium for HC bioremediation is not yet well understood. Here, we analyzed the complete genomes of these marine bacterial strains accompanied by a phylogenetic reconstruction along with 138 bacterial strains. Synteny between complete genomes of the same species or genus, revealed high conservation among strains of the same species, covering over 91% of their genomic sequences. Functional predictions highlighted a high abundance of genes related to HC degradation, which may result in functional redundancy within the consortium; however, unique and complete gene clusters linked to aromatic degradation were found in the four genomes, suggesting substrate specialization. Pangenome gain and loss analysis of genes involved in HC degradation provided insights into the evolutionary history of these capabilities, shedding light on the acquisition and loss of relevant genes related to alkane and aromatic degradation. Our work, including comparative genomic analyses, identification of secondary metabolites, and prediction of HC-degrading genes, enhances our understanding of the functional diversity and ecological roles of these marine bacteria in crude oil-contaminated marine environments and contributes to the applied knowledge of bioremediation.

Biodegradation, Environmental↗
PubMed1978

Hazards of disease transfer from marine mammals to land mammals: review and recent findings.

In a 5-year study (1972-1977) of microbial agents isolated from both clinically normal and diseased marine mammals, it was shown that certain disease agents are widespread in a diversity of ocean populations and that some are also transmissible to a number of terrestrial mammal species. Leptospira interrogans serovar pomona has been isolated repeatedly from 2 species of pinnipeds (Zalophus californianus califonianus and Callorhinus ursinus). Some of the more important bacterial pathogens for land mammals that were isolated from wild marine mammals are Pseudomonas mallei, Clostridium chauvoei, C novyi, Neisseria mucosa var heidelbergensis, Klebsiella pneumoniae, Salmonella spp, and Pasteurella multocida. Numerous serotypes of viruses classified as caliciviruses were isolated from a variety of marine mammals. Some of these are known to infect several land mammal species including swine horses, and primates. For this reason., precautions should be taken to ensure that disease agents shed by captive marine mammals are not transmitted to susceptible terrestrial mammals, including animal handlers and other human beings.

Animals↗
PubMed2024

Oceanic islands act as drivers for the genetic diversity of marine species: Cardita calyculata (Linnaeus, 1758) in the NE Atlantic as a case-study.

Geographic distribution, as well as evolutionary and biogeographic processes and patterns of marine invertebrate benthic species are strongly shaped by dispersal ability during the life cycle. Remote oceanic islands lie at the brink of complex biotic and abiotic interactions which have significantly influenced the biodiversity patterns we see today. The interaction between geological environmental change and taxon-specific dispersal modes can influence species evolutionary patterns, eventually delimiting species-specific biogeographic regions. In this study, we compare the population genetic patterns of the marine bivalve Cardita calyculata in the northeast Atlantic, discussing the role of Macaronesian islands during past climatic cycles. The genetic structure and diversity patterns were outlined based on SSR-GBAS loci of 165 individuals and on the mitochondrial COI marker of 22 individuals from the Canary Islands, Madeira, Azores and the Mediterranean. The highly structured genetic pattern found among regions and within archipelagos suggests the central role of oceanic islands in promoting the divergence of the species in both the NE Atlantic and the Mediterranean. The high degree of divergence in the COI dataset (> 7%) suggests the existence of potential cryptic speciation that needs to be further explored with a more comprehensive sampling. Such patterns are only congruent with a scenario where C. calyculata populations were maintained during glacial/interglacial cycles, supporting the role of the studied archipelagos as drivers of diversity for marine biota. We stress the importance of developing studies for species with various life history and dispersal modes. In such a way, a more profound understanding of the biogeographic and evolutionary significance of oceanic islands can catalyse directed conservation efforts, especially in the context of the ongoing climate crisis.

Animals↗
PubMed2026

Marine Vibrio Biocatalysts as Unique Green Transformation (GX) Tools at the Time to Sustainable Development Goals (SDGs).

Vibrios have sustained various types of ocean ecosystems, being key players in marine mineral cycles and essential partners in specific groups of marine life. Observed genome plasticity and metabolic versatility are some of the unique biological features of vibrios, and these traits could contribute in expanding their ecological niche in marine environments. Vibrios are now recognized as ecophysiologically essential microbial species for our planet. At the time to "Sustainable Development Goals" (SDGs), their genome plasticity and metabolic versatility have also been studied with the aim of solving global issues such as energy production and plastic pollution by creating new microbial biocatalysts. Here, we introduce recent progress on the application of vibrios aiming towards green transformation (GX).

Vibrio↗
PubMed2026

Symbiosis reshapes metabolism of sulfate-reducing bacteria in gutless marine worms.

Sulfate-reducing bacteria (SRB) are widespread in marine and terrestrial environments, where they often form syntrophic associations with bacteria, archaea, and eukaryotes. Among the most intimate of these are multipartite symbioses in gutless marine oligochaete worms, which host SRB and sulfur-oxidizing endosymbionts that engage in a syntrophic exchange of sulfur compounds. Despite decades of research on free-living SRB, the metabolic traits that enable SRB to persist in symbiosis, and how these differ across hosts and environments, remain poorly understood. We show that a globally distributed clade of symbiotic SRB, which we named Candidatus Desulfoconcordia, has a conserved core metabolism that diverges from free-living relatives. Using comparative genomics and metaproteomics, we reveal that these endosymbionts retain key traits of SRB such as sulfate reduction, complete oxidation of acetate to CO2, amino acid degradation for nitrogen acquisition, and transport of essential nutrients. However, they exhibit a more oxygen-tolerant metabolism and lack typical nutrient-scavenging mechanisms of free-living SRB. One trait, the glyoxylate bypass, was consistently expressed in situ and may serve both in reactive oxygen species defence and in biomass generation. The expression of oxygen-tolerant pathways, coupled with the loss of nutrient-scavenging functions, indicate specialization to a host-associated, redox-fluctuating environment distinct from that of free-living SRB. The symbiont genomes are also larger than those of free-living relatives, contrasting with genome reduction in many endosymbionts and reinforcing the importance of metabolic versatility. Our findings provide a framework for understanding how metabolic flexibility enables SRB to persist in long-term multipartite symbioses across diverse marine ecosystems.

Symbiosis↗
PubMed2026

Unlocking the unexplored AMPSphere in marine rare species.

BACKGROUND: Antimicrobial peptides (AMPs) have advantages over traditional antibiotics in fighting against drug-resistant bacterial infections. Natural microbial communities are considered as the priority targets for next-generation AMP bioprospecting initiatives. While progress has been made in characterizing AMPs from the dominant microbial taxa in natural ecosystems, current research largely overlooks the biosynthetic potential of rare species. Given their distinct evolutionary pressures, rare species likely produce AMPs with novel structures and unconventional mechanisms of action. RESULTS: In this study, enrichment cultivation of a marine biofilm was conducted in 138 carbon source- and oxygen level-based conditions, followed by metagenomic sequencing using both Illumina and Nanopore platforms. Analysis of 435 high-quality genomes derived from the metagenomes suggests that these bacterial strains are significantly underrepresented (<&#x2009;0.01%) in global marine biofilm communities. Through multi-model prediction, we identified 3,054,472 candidate AMPs from the genomes, including 1048 high-confidence ones, thereby significantly expanding the previously known AMPSphere. Furthermore, AMPs derived from the rare bacterial species exhibit unique sequence characteristics, structural diversity, remarkable stability under diverse pH conditions and pepsin exposure, and strong therapeutic potential in animal models, reflecting their specialized adaptive and defensive strategies developed within ecological systems. CONCLUSIONS: The features of the underexplored AMPs from low-abundance bacteria in marine biofilms provide valuable resources and theoretical foundations for the development of highly effective antimicrobial agents. Video Abstract.

Biofilms↗
PubMed1977

Occurrence and transformation of arsenic in the marine environment.

Among the trace elements, arsenic appears to possess a unique position in the environment. When comparing terrestrial and marine organisms there seems to be a significant difference between both level and chemical forms of arsenic. The level of arsenic in terrestrial organisms is seldom above 1 ppm (dry material) whereas the corresponding values for marine organisms vary from several parts per million up to more than 100 ppm. Furthermore, results so far show that marine organisms are able to convert inorganic arsenic into organic arsenic compounds. No evidence points to a corresponding ability in the terrestrial ones. In the aquatic organisms the arsenic is present as both lipid soluble and water soluble compounds. The water-soluble organic arsenic compounds have a basic character and are very stable to chemical and metabolic breakdown.

Animals↗
PubMed2025

Marine endophytes: biosynthetic engines for novel bioactive metabolites.

Marine endophytes are prolific sources of structurally diverse secondary metabolites with significant pharmaceutical potential, including anticancer, antimicrobial, and antioxidant agents. However, their commercial utilization is hindered by genomic instability in axenic cultures and inconsistent metabolite yields. While current studies focus on symbiotic interactions and compound discover, critical gaps persist in harnessing their biosynthetic capabilities. This review synthesizes knowledge on marine fungal metabolites and proposes a paradigm shift toward resource-driven research. It addresses strain improvement limitations and suggests strategies like mutagenesis, protoplast fusion, and metabolic engineering to bolster production stability and efficiency. The paper also discusses biological process optimization, including fermentation tuning, inducer and precursor addition, and adsorbent use, to enhance natural product synthesis. By identifying these research gaps and proposing a strategic roadmap, the review advances the stable and scalable production of bioactive metabolites, unlocking the commercial and therapeutic potential of marine endophytic fungi.

bioactive metabolites↗
PubMed2026

Canalesolide A, a Structurally Unique Polyhydroxy Macrolide from the Marine Cyanobacterium Okeania sp. with Potent Antitrypanosomal Activity.

The discovery of structurally novel natural products remains central to expanding biologically relevant chemical space, particularly within underexplored marine metabolite classes. Herein, we report the discovery and complete structural elucidation of canalesolide A, a new polyhydroxylated macrolide isolated from the marine cyanobacterium Okeania sp. The compound was identified through an integrated workflow combining phenotypic screening against Trypanosoma brucei and LC-MS/MS-based molecular networking, enabling rapid prioritization of bioactive fractions and dereplication of known metabolite families. Spectroscopic analysis revealed that canalesolide A belongs to the bastimolide-related class of macrolides but exhibits a distinct structural architecture. Its structure was established by integrating ultrahigh-resolution NMR spectroscopy, empirical configurational analysis of polyol systems, targeted model compound synthesis, and controlled chemical degradation and derivatization. This combined strategy resolved stereochemical motifs that were inaccessible by direct analysis of the intact macrolide alone, providing a transferable approach for assigning densely oxygenated marine macrolides. Genome mining identified the putative biosynthetic gene cluster and proposed biosynthetic pathway for a bastimolide-related macrolide. Canalesolide A displays potent, low nanomolar antitrypanosomal activity against human-infective subspecies of T. brucei with rapid elimination of parasites within 1 h at 1 &#x3bc;M. Although moderate mammalian cytotoxicity was observed, preliminary in vivo efficacy/toxicity studies in infected mice suggest a narrow therapeutic window highlighting the need for improved selectivity. This study expands the structural and biosynthetic diversity of polyhydroxylated macrolides and establishes a generalizable framework for resolving stereochemically complex natural products.

Macrolides↗
PubMed2025

Mapping Species Birth Across the Recombination Landscapes of Marine Snails.

Understanding the drivers of heterogeneous genomic divergence is essential for uncovering the mechanisms that generate and constrain biodiversity. The extent to which adaptation and speciation are facilitated by reorganisation of the recombination landscape remains untested in many systems. Marine ecosystems, with their dynamic and fluid habitats, offer a compelling context to investigate genomic divergence. In this study, we mapped genomic divergence and selection across recombination landscapes of parapatric marine snail sister species that we show have recently undergone secondary contact. Regions of reduced recombination were enriched for genes exhibiting signatures of negative selection, whereas regions of high recombination were associated with genes under putative positive selection. Notably, the recombination landscape of the population in parapatry of one species (Scurria viridula) differs markedly from that of the other population within this same species, highlighting the role of introgression in reshaping recombination landscapes. In the other species (Scurria zebrina), conservation of the recombination landscape and divergent selection among populations suggest trapping of beneficial allele combinations in regions of low recombination maintains the identity of this species. Among species, signals of divergence with gene flow consistently cluster within specific genomic regions characterised by high recombination rate variation among the populations of S. viridula. These results challenge traditional theoretical expectations of recombination evolution by showing that the causes of genomic divergence can be population-specific. This study demonstrates that recombination landscapes are key modulators of genomic divergence, with contemporary evolutionary shifts that could enable populations to adapt to distinct environments. Our findings provide new insights into the interplay between recombination, selection, and gene flow during speciation, underscoring the complexity of evolutionary trajectories in marine systems.

Genetic Introgression↗
PubMed2025

Homoploid Hybrid Speciation in a Marine Pelagic Fish.

Homoploid hybrid speciation (HHS) is an enigmatic evolutionary process where new species arise through hybridisation of divergent lineages without changes in chromosome number. Although increasingly documented in various taxa and ecosystems, convincing cases of HHS in marine fishes have been lacking. This study presents a possible case of HHS in a pelagic marine fish based on comprehensive genomic, morphological, and ecological analyses. Population genomics, species tree estimation, and tests of introgression and admixture identified three sympatric clusters in Megalaspis cordyla in the western Pacific and the admixed nature of one cluster between the others. Moreover, model-based demographic inference favoured a hybrid speciation scenario over introgression for the origin of the admixed cluster. While contemporary gene flow suggested partial reproductive isolation, examination of occurrence data and ecologically relevant morphological characters suggested ecological differences between the clusters, potentially contributing to the reproductive isolation and niche partitioning in sympatry. The clusters are also morphologically distinguishable and thus can be taxonomically recognised as separate species. The hybrid cluster is restricted to the coasts of Taiwan and Japan, where all three clusters coexist. The parental clusters are additionally found in lower latitudes, where they display non-overlapping distributions. Given the geographical distributions, estimated times of species formation, and patterns of historical demographic changes, we propose that the Pleistocene glacial cycles were the primary driver of HHS in this system. We also develop an ecogeographic model of HHS in marine coastal ecosystems, including a novel hypothesis to explain the initial stages of HHS.

Animals↗
PubMed1975

Chlorinated hydrocarbon pollutants and photosynthesis of marine phytoplankton: a reassessment.

The chlorinated hydrocarbons DDT and PCB's (polychlorinated biphenyls), ubiquitous pollutants of the marine environment, have been observed to reduce the cell division rate of marine phytoplankton, thereby indirectly reducing the total photosynthetic carbon fixation in treated cultures. The photosynthetic capacity of each cell was not affected. Total marine photosynthesis will likely remain undiminished by these compounds, although alterations in phytoplankton communities through selective toxicity could effect herbivore populations.

Cell Division↗
PubMed1977

Comparison between two methods of assaying relative microbial activity in marine environments.

Two methods for determining relative microbial activity in the marine environment were compared. In one method, a single concentration of a labeled substrate was used to calculate rates of substrate utilization; in the other, multiple concentrations of the same substrate (heterotrophic activity method) were used to calculate maximum potential substrate utilization rates. These studies were made on 232 seawater and 79 sediment samples taken from a variety of marine environments. The highest correlations between these two methods were seen in the sediment samples tested. The lowest correlation coerfficient seen in the sediment samples was 0.90, and the highest was 0.98. In seawater samples (six studies), the lowest correlation coefficient was 0.77 and the highest was 0.95. The correlation between these two methods was also substrate concentration dependent. Higher correlation coefficients were observed when higher substrate concentrations were used. Under certain conditions, these two methods appear to be comparable for estimating relative levels of microbial activity in the marine environment.

Antarctic Regions↗
PubMed1978

Incidence of Vibrio parahaemolyticus bacteriophages and other Vibrio bacteriophages in marine samples.

Vibrio bacteriophages were isolated by enrichment from 177 of 643 samples of marine molluscan shellfish, crustaceans, seawater, and sediments. The predominant bacteriophage types isolated were specific for some strains of Vibrio parahaemolyticus. A high frequency of phage isolations was also observed with strains of agar-digesting vibrios (21 of 56) and psychrophilic vibrios (14 of 72) that were originally isolated from non-shellfish growing areas. No bacteriophages were isolated against V. alginolyticus and only rarely for V. anguillarum even though these were the two most abundant species found in near-shore environments. No V. cholerae phages were isolated. It was also determined from quantitative studies on the Pacific oyster (Crassostrea gigas) obtained from two environments in Washington and Oregon that the titers of V. parahaemolyticus bacteriophages increased with increasing seasonal water temperatures and that this was proportional to the increase in numbers of mesophilic vibrios and not with the incidence of V. parahaemolyticus. Titers of V. parahaemolyticus bacteriophages occasionally exceeded 10(6) per g of oyster during the summer months. Specific V. parahaemolyticus bacteriophages were also isolated from market seafoods and other marine samples that originated in cold environments where no mesophilic vibrios are expected to be found. The possibility that V. parahaemolyticus bacteriophages originate from Vibrio spp. other than V. parahaemolyticus and the role of these bacteriophages in the ecology of marine vibrios are discussed.

Animals↗
PubMed1979

Repair detection procedure for enumeration of fecal coliforms and enterococci from seafoods and marine environments.

The repair detection procedure of Speck et al. (Appl. Microbiol. 29:549-550, 1975) was adapted for the enumeration of coliforms, fecal coliforms, and enterococci in seafood and environmental samples. Samples were pour plated with Trypticase soy agar, followed by a 1- to 2-h incubation to effect repair; the plates were then overlaid with the selective medium and incubated. Violet red bile agar and an incubation temperature of 45 degrees C were used as the selective conditions for fecal coliforms, and KF streptococcal agar was used for the enumeration of enterococci. The method was more efficient than the standard most-probable-number method for fecal coliform enumeration and also allowed enumeration of the injured cells, which might have remained undetected when selective medium in the most-probable-number method was used. The repair detection method effectively recovered the injured portion of the population of enterococci capable of growing on KF streptococcal agar. The repair enumeration method was not suitable for coliforms in marine samples because associative marine bacteria mimicked coliforms in violet red bile agar plates incubated at 35 degrees C. The marine bacteria did not grow at 45 degrees C and therefore did not interfere with fecal coliform enumeration.

Escherichia coli↗
PubMed1979

Interaction of the mannosephilic lectins of Pseudomonas aeruginosa with luminous species of marine enterobacteria.

The marine bacteria Beneckea harveyi and Photobacterium leiognathi were shown to bear mannose-containing binding sites for the mannosephilic lectins of Pseudomonas aeruginosa and concanavalin A (Con A). The interaction between the lectins and the marine bacteria was demonstrated by the bacteriagglutination test, by adsorption of the lectins onto the bacteria and by mannose-specific peroxidase-binding to the lectin-coated bacteria. Treatment of the bacteria with formaldehyde, phenol, ethanol or boiling them for 15 min, did not alter their ability to adsorb the lectins. The growth rate of the marine bacteria was unaffected when either the Pseudomonas lectins or Con A was added to the culture medium.

Concanavalin A↗
PubMed1979

Candida lipolytica isolated from Guanabara Bay and its ability to grow in marine and estuarine conditions.

Although the petroleum degrading ability of Candida lipolytica is well known, its ability to grow in seawater is questionable. Sixteen strains of C. lipolytica were isolated from marine sites in Rio de Janeiro. Some variations from the standard description were noted including strains intermediate between the varieties lipolytica and deformans. A representative strain which grew well on petroleum was found to grow well in marine and estuary conditions which reinforces its potential as a seed organism for marine oil spills.

Candida↗