Lucas Ruberto

Plastic pollution has become a global environmental issue, yet little is known about how plastics degrade and interact with microbes under polar conditions, especially upon entering the marine environment. Here, we report the first in situ time-series experiment investigating early microbial colonization and surface oxidation of virgin plastics in Antarctic coastal waters. Virgin pellets of polystyrene (PS), low-density polyethylene (LDPE), and polyethylene terephthalate (PET) were deployed in Potter Cove (King George/25 de Mayo Island) for 31 days. Biofilm communities were characterized using 16S rRNA amplicon sequencing, while polymer surface chemistry was assessed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). Across all polymers, plastisphere assemblages were dominated by psychrophilic or psychrotolerant taxa. Plastic-associated communities showed consistent temporal changes over the 31-day exposure, with shifts in the relative abundance of taxa associated with different stages of biofilm development. Exposure time was a stronger determinant of community composition than polymer type. FTIR analyses revealed significant surface oxidation in PS and LDPE, particularly at days 21 and 31, with increases in hydroxyl, carbonyl, and carbon–oxygen indices. PET showed great variability and no consistent oxidative signals over the study period. The chemical shifts partially covaried with taxa associated with later sampling points, suggesting potential, but not yet conclusive, links between biofilm succession and polymer weathering. Our results provide some novel insights into the early dynamics of microbial colonization on plastic surfaces and polymer surface alteration in Antarctic waters, highlighting the importance of integrating microbial and chemical perspectives to understand plastic fate in polar ecosystems.

More than six decades of human activity in Antarctica resulted in chronic diesel contamination of soils surrounding research stations. Phytoremediation assisted by the native vascular plant Deschampsia antarctica is one of the few remediation strategies compatible with the Antarctic Treaty System guidelines. Securing suitable root-associated microbial resources is central to this approach. This work characterized the bacterial communities of the rhizosphere and root endosphere of D. antarctica growing in a chronically diesel-contaminated soil at Carlini Station and in three pristine sites on 25 de Mayo (King George) Island, South Shetland Islands, combining culture-independent 16S rRNA gene amplicon sequencing, PICRUSt2 functional prediction and culture-dependent bacterial strain isolation. The rhizospheric microbial community was consistently more diverse than those inhabiting the endosphere and was more strongly structured by site and associated soil physicochemical variables, with the contaminated site showing the most distinct composition, whereas the endosphere remained comparatively stable and host-selected. The community associated with the chronically contaminated site showed pronounced compositional differences and higher predicted abundances of hydrocarbon-degradation pathways in the rhizosphere. Polaromonas, Rhodococcus, Mycobacterium and Devosia were repeatedly associated with the community from the contaminated site across taxonomic, biomarker and predicted functional analyses. Members of the genera Polaromonas, Rhodococcus and Devosia were also recovered in culture. These taxa represent suitable candidates for the future development of microbe-assisted phytoremediation strategies in Antarctica.

Antarctic ecosystems host psychrophilic and psychrotolerant fungi whose set of adaptations represents a biotechnologically valuable and underexploited genetic resource. This review synthesizes the current literature on the bioactive secondary metabolites and cold-active enzymes produced by Antarctic fungi, together with their biomedical, cosmetic, and industrial applications, and examines the regulatory and ethical framework governing their exploitation under the Antarctic Treaty System. Antioxidant, antimicrobial, anti-inflammatory, and photoprotective compounds—together with cold-active lipases, proteases, and amylases—were identified as the main classes of biotechnologically relevant molecules, with the Cadophora genus and the lipase B of Moesziomyces antarcticus (Candida antarctica) (CALB) highlighted as paradigmatic cases. Evidence considered shows that, despite promising bioactivities and at least one globally commercialized product (CALB/Novozym^®), most findings remain confined to the academic level, revealing an early-stage translational field. The CALB case further exposes an unresolved regulatory gap: minimal, non-destructive sampling can generate substantial commercial value without any derived benefit for either the country of the researchers involved in the isolation, Antarctica, or the international community. These findings underscore the need for a specific legal instrument within the Antarctic Treaty System establishing rational bioprospection guidelines and mechanisms for equitable benefit-sharing.

Diesel spills represent a significant challenge to Antarctic ecosystems, particularly in ice‐free areas where stations and wildlife co‐occur. Taking into consideration the Protocol on Environmental Protection to the Antarctic Treaty, the use of native species emerges as a suitable solution for this problem. Here, we evaluate the tolerance and potential of the native grass Deschampsia antarctica for phytoremediation of diesel‐contaminated soils, combining in vitro and field assays at Carlini Research Station. Using a dose–response approach, we measured biometric parameters, photosynthetic pigments, and antioxidant enzyme activities under varying diesel concentrations. In vitro experiments suggested high half‐maximal inhibitory dose (ID50) values: 3741, 5709 and 8425 mg kg ⁻¹ for root growth, chlorophyll content, and total biomass, respectively. Field experiments showed a 14.5%, 47.9%, and 27.5% reduction in biomass, root growth and chlorophyll content at the highest diesel concentration (40,000 mg kg ⁻¹ ), suggesting that root growth is the most sensitive parameter. Antioxidant enzyme activities, including guaiacol peroxidase (GPX, EC 1.11.1.7) and superoxide dismutase (SOD, EC 1.15.1.1), presented contrasting trends between in vitro and field conditions, underscoring the influence of environmental factors on stress responses. These results propose root growth as an indicator of diesel‐induced stress, contributing to optimizing phytoremediation strategies. Overall, our findings highlight the plant's tolerance to high contaminant levels, even under conditions of maximum bioavailability, and demonstrate its potential for phytoremediation in extreme environments, supporting the development of sustainable remediation strategies for Antarctic soils.

SARS-CoV-2 was identified as the pathogenic agent causing the COVID-19 pandemic. Among the proteins codified by this virus, the Spike protein is one of the most-external and -exposed. A fragment of the Spike protein, named the receptor binding domain (RBD), interacts with the ACE2 receptors of human cells, allowing the entrance of the viruses. RBD has been proposed as an interesting protein for the development of diagnosis tools, treatment, and prevention of the disease. In this work, a method for recombinant RBD production using Pichia pastoris as a cell factory in a stirred-tank bioreactor (SRTB) up to 7 L was developed. Using a basal saline medium with glycerol, methanol, and compressed air in a four-stage procedure, around 500 mg/L of the raw RBD produced by yeasts (yRBD) and 206 mg/L of purified (>95%) RBD were obtained. Thereby, the proposed method represents a feasible, simple, scalable, and inexpensive procedure for the obtention of RBD for diagnosis kits and vaccines’ formulation.

SARS-CoV-2 was identified as the pathogenic agent causing the COVID-19 pandemic. Among the proteins codified by this virus, the Spike is one of the most external and exposed. A fragment of the Spike protein, named the Receptor Binding Protein (RBD) interacts with the ACE2 receptors of human cells, allowing the entrance of the viruses. RBD has been proposed as an interesting protein for the development of diagnosis tools, treatment and prevention of the disease. In this work, a method for recombinant RBD production using Pichia pastoris as a cell factory in a Stirred Tank Bioreactor (SRTB) up to 7 L was developed. Using a basal saline medium with glycerol, methanol and compressed air in a four stages procedure, around 500 mg/L of raw yRBD (RBD produced by yeasts) and 206 mg/L of purified (>95%) RBD were obtained. Thereby, the proposed method represents a feasible, simple, scalable and cheap procedure for the obtention of RBD for diagnosis kits and vaccines formulation

The Antarctic fungus Cadophora malorum produces previously undescribed cyclic heptapeptides (cadophorin A and B) containing an anthranilic acid residue. The planar structure of these peptides was determined by high-resolution mass spectrometry combined with extensive 1D and 2D NMR spectroscopy. The absolute configuration of the amino acids was determined by Marfey’s method, with HPLC analysis of FDVA (Nα-(2,4-dinitro-5-fluorphenyl)-l-valinamide) derivatives making use of a PFP column. Remarkably, cadophorin 2 possesses both the uncommon d-Ile and d-allo-Ile in its structure. The peptides have metal binding properties as shown by LCMS with post column addition of metal salt solutions. These results were supported by DFT calculations. Graphical Abstract

Microbial associations arise as useful tools in several biotechnological processes. Among them, bioremediation of contaminated environments usually takes advantage of these microbial associations. Despite being frequently used, these associations are indicated using a variety of expressions, showing a lack of consensus by specialists in the field. The main idea of this work is to analyze the variety of microbial associations referred to as “microbial consortia” (MC) in the context of pollutants biodegradation and bioremediation. To do that, we summarize the origin of the term pointing out the features that an MC is expected to meet, according to the opinion of several authors. An analysis of related bibliography was done seeking criteria to rationalize and classify MC in the context of bioremediation. We identify that the microbe’s origin and the level of human intervention are usually considered as a category to classify them as natural microbial consortia (NMC), artificial microbial consortia (AMC), and synthetic microbial consortia (SMC). In this sense, NMC are those associations composed by microorganisms obtained from a single source while AMC members come from different sources. SMC are a class of AMC in which microbial composition is defined to accomplish a certain specific task. We propose that the effective or potential existence of the interaction among MC members in the source material should be considered as a category in the classification as well, in combination with the origin of the source and level of intervention. Cross-kingdom MC and new developments were also considered. Finally, the existence of grey zones in the limits between each proposed microbial consortia category is addressed. Key points • Microbial consortia for bioremediation can be obtained through different methods. • The use of the term “microbial consortia” is unclear in the specialized literature. • We propose a simplified classification for microbial consortia for bioremediation.