The use of microalgae in biotechnological processes has received much attention worldwide. This is primarily due to the fact that they are inexpensive to grow, requiring only sunlight and CO₂, whilst lending themselves to a range of uses, such as to reduce CO₂ levels, as fish feed, in biofuel production, for the generation of secondary metabolites of interest, and in bioremediation. These features mean that microalgae are excellent candidates for the implementation of a range of eco-friendly technologies. Here, we investigated the behavior and feasibility of the use of the microalgal strain Tetraselmis marina AC16-MESO against heavy metal contamination focused on potential use in bioremediation. The following key parameters were recorded: (i) the sedimentation efficiency, which reached 95.6% after five hours of decantation; (ii) the ion tolerance (Ca²⁺, Co²⁺, Cu²⁺, Fe³⁺, Mn²⁺ and Ni²⁺) at concentrations of 0.1, 1.0, 5.0, 10.0 and 20.0 mg*L⁻¹ and (iii) ion removal efficiency (Cu²⁺, Fe³⁺ and Mn²⁺). Our results indicated a higher tolerance for iron and calcium (20 ± 1.10 mg*L⁻¹; 100 ± 8.10 mg*L⁻¹), partial to nickel, manganese and copper (4.4 ± 0.10 mg*L⁻¹; 4.4 ± 0.15 mg*L⁻¹; 5 ± 1.25 mg*L⁻¹) and less for cobalt (0.1 ± 0.20 mg*L⁻¹). Moreover, removal efficiency of 40–90% for Cu²⁺, 100% for Fe³⁺, and 20–50% for Mn²⁺ over a 72 hours period, for ion concentrations of 1.0 and 5.0 mg*L⁻¹.

The wide rocky coastline of the Antofagasta hosts an intertidal ecosystem in which the species that inhabit it are routinely exposed to a wide range of physical and chemical conditions and have therefore evolved to tolerate extremes. In the search for new species of potential biotechnological interest with adaptations to a wide range of environmental conditions, the isolation and characterization of microalgae from these ecosystems is of great interest. Here, a new microalgal strain, Tetraselmis marina AC16-MESO, is described, which was isolated from a biofilm collected on the intertidal rocks of the Antofagasta coast (23°36′57.2″ S, 70°23′33.8″ W). In addition to the morphological characterization, 18S and ITS sequence as well as ITS-2 secondary structure analysis revealed an identity of 99.76% and 100% with the species Tetraselmis marina, respectively. The analyses of the culture characteristics and biochemical content showed similarities with other strains that are frequently used in aquaculture, such as the species Tetraselmis suecica. In addition, it is tolerant of a wide range of salinities, thus allowing its culture in water of varying quality. On the other hand, added to these characteristics, the results of the improvement of the lipid content in stressful situations of salinity observed in this study, together with other antecedents such as the potential in bioremediation already published for this strain by the same research group, present a clear example of its biotechnological plasticity. It is noteworthy that this strain, due to its characteristics, allows easy collection of its biomass by decantation and, therefore, a more cost-efficient harvesting than for other microalgal strains. Therefore, this new strain of Tetraselmis marina, first report of this species in Chile, and its morphologically, molecularly and biochemically description, presents promising characteristics for its use in biotechnology and as feed for aquaculture.

The dinoflagellate Prorocentrum triestinum forms high biomass blooms that discolor the water (red tides), which may pose a serious threat to marine fauna and aquaculture exploitations. In this study, the algicidal effect of a bacterial strain (0YLH) belonging to the genus Shewanella was identified and evaluated against P. triestinum. The algicidal effects on the dinoflagellate were observed when P. triestinum was exposed to cell-free supernatant (CFS) from stationary-phase cultures of the 0YLH strain. After 24 h exposure, a remarkable reduction in the photosynthetic efficiency of P. triestinum was achieved (55.9%), suggesting the presence of extracellular bioactive compounds produced by the bacteria with algicidal activity. Furthermore, the CFS exhibited stability and maintained its activity across a wide range of temperatures (20–120 °C) and pH values (3–11). These findings highlight the algicidal potential of the bacterium Shewanella halifaxensis 0YLH as a promising tool for the environmentally friendly biological control of P. triestinum blooms.

In the present study, nine Enterobacteriaceae species present in wastewater were isolated and identified, and loop-mediated isothermal amplification (LAMP) was developed for the detection of Enterobacteriaceae by designing primers based on the mcr-1, KPC, OXA-23, and VIM genes, which are recognized markers of antimicrobial resistance (AMR) transmission during microalgal bioremediation treatment. The developed assays successfully detected four strains positive for mcr-1 gene-asociated resistance (Acinetobacter baylyi, Klebsiella pneumoniae, Morganella morganii, and Serratia liquefaciens), three strains for KPC gene-associated resistance (Acinetobacter sp., Escherichia coli 15499, and Morganella morganii), seven strains for OXA-23 gene-associated resistance (Acinetobacter baylyi, Enterobacter hormaechi, Enterobacter cloacae, Escherichia coli 15922, Escherichia coli 51446, Morganella morganii, and Serratia liquefaciens), and three strains for resistance to the VIM gene-associated resistance (Acinetobacter baylyi, Acinetobacter sp., and Enterobacter hormaechi) from a single colony. A reduction in microbiological load of 93.6% was achieved at 15 colony-forming units (CFU) mL⁻¹, utilizing EMB agar and LAMP values of 0.142 ± 0.011 for the mcr-1 gene, 0.212 ± 0.02 for the KPC gene, 0.233 ± 0.006 for the OXA-23 gene, and 0.219 ± 0.035 for the VIM gene. Furthermore, bioremediation efficiency values of 71.6% and 75% for total nitrogen and phosphorus, respectively, were observed at 72 h of treatment in open pond microalgal remediation systems (MRS). This study demonstrated that the LAMP technique is faster and more sensitive than traditional detection methods, such as CFU, for Enterobacteriaceae. Consequently, this method may be considered for the detection of microbiological quality indicators within the water treatment industry.