Examinando por Autor "Riquelme, Carlos"
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Ítem Current Trends and Biotechnological Innovations in Biofouling Control of RO Membranes in Desalination Systems(MDPI, 2025) Cruz-Balladares, Victoria; Vera-Villalobos, Hernan; Riquelme, Carlos; Silva Aciares, FernandoBackground: Water scarcity is a pressing global challenge increasingly addressed by ad-vanced desalination that converts seawater into potable water. Reverse osmosis and ultra-filtration dominate because they deliver permeate with very low impurities. Their principallimitation is membrane biofouling, which causes clogging, raises energy, operation, andmaintenance costs, and shortens membrane life. Multiple approaches mitigate biofouling—most notably pretreatment trains and engineered surface coatings—but cleaning remainsthe most decisive remediation pathway. Current practice distinguishes physical, chemical,and biological cleaning. Biological cleaning has gained momentum by exploiting microor-ganisms that inherently counter biofilms. These strategies include targeted secretion ofenzymes and antifouling metabolites, and the application of whole-cell culture super-natants containing the full suite of secreted components. In addition, predatory bacteriacan infiltrate established biofilms and eradicate them by lysing prey, thereby acceleratingthe removal of adherent biomass. Progress across these bio-based approaches signals mean-ingful advances in fouling control and could substantially improve the efficiency, reliability,and sustainability of desalination facilities. Collectively, they underscore the transformativepotential of biological antifouling agents in operational systems. Realizing that potentialwill require rigorous evaluation of technical performance, long-term stability, compatibilitywith polyamide membranes, regulatory acceptance, and environmental safety, ultimatelyalongside scalable production and cost-effective deployment in full-scale planÍtem Insights into the diversity and survival strategies of soil bacterial isolates from the Atacama Desert(Frontiers Media SA, 2024) Reverdy, Alicyn; Hathaway, Daniel; Jha, Jessica; Michaels, Gabriel; Sullivan, Jeffrey; Diaz McAdoo, Daniela; Riquelme, Carlos; Chai, Yunrong; Godoy Carter, VeronicaThe Atacama Desert, the driest, with the highest radiation, and one of the most ancient deserts in the world, is a hostile environment for life. We have a collection of 74 unique bacterial isolates after cultivation and confirmation by 16S rRNA gene sequencing. Pigmentation, biofilm formation, antimicrobial production against Escherichia coli MG1655 and Staphylococcus aureus HG003,and antibiotic resistance were assessed on these isolates. We found that approximately a third of the colonies produced pigments, 80% of isolates formed biofilms, many isolates produce growth inhibiting activities against E. coliand/orS. aureus, and many were resistant to antibiotics. The functional characterization of these isolates gives us insight into the adaptive bacterial strategies in harsh environments and enables us to learn about their possible use in agriculture,healthcare, or biotechnology.Ítem Microchloropsis gaditana as a Natural Antimicrobial with a One Health Approach to Food Safety in Farmed Salmon(MDPI, 2025) Diaz, Nelson; Munoz, Susana; Medina, Alberto; Riquelme, Carlos; Lozano-Munoz, IvonneSustainably farmed Atlantic salmon could drive global food system solutions by contributing essential nutrients to the human diet while delivering high-quality protein. One of the biggest obstacles to sustainable salmon aquaculture in Chile is the prevalence of piscirickettsiosis disease caused by the Gram-negative bacteria Piscirickettsia salmonis and the excessive amount of antibiotics used to eradicate this disease. Farmed salmon products can be consumed without prior processing and therefore present a substantial risk for the transfer of resistant pathogens to humans. Antibiotics also carry the risk of antibiotic residues and damage to the environment. An alternative to antibiotics is the use of natural antimicrobials without the negative influence on the consumer’s microbiome. Here, we evaluate the potential antimicrobial activity against P. salmonis of the marine microalgae Microchloropsis gaditana. A non-genetically modified M. gaditana was grown with nitrogen deprivation to improve the synthesis of the eicosapentaenoic fatty acid (EPA). A spray-dried M. gaditana concentrate (Mg) was elaborated and given to Atlantic salmon for a period of 49 days, and serum and fillet samples were collected. Our results showed a significant increase in the nutritional quality improving the levels of EPA+ Docosapentaenoic acid (DPA) (23%) and Vitamin D3 (106%) of the fillets treated with Mg. Fish fed serum were challenged with P. salmonis, and serum antibacterial activity was measured. Sera from fish fed Mg-enriched diets showed a significant increase in antibacterial activity (85.68%) against P. salmonis. Our results indicate that Mg can be used as a viable alternative to address the critical problem of microbial resistance and to assure consumers that farm-raised Atlantic salmon is safe.Ítem Nitrification characteristics and microbial community changes during conversion of freshwater to seawater in down-flow hanging sponge reactor(ELSEVIER, 2024) Akamine, Takumi; Nagai, Mami; Watari, Takahiro; Netsu, Hirotoshi; Adlin, Nur; Satanwat, Penpicha; Riquelme, Carlos; Hatamoto, Masashi; Yamaguchi, TakashiIn recirculating aquaculture systems (RAS), maintaining water quality in aquaculture tanks is a paramount factor for effective fish production. A down-flow hanging sponge (DHS) reactor, a trickling filter system used for water treatment of RAS that employs sponges to retain biomass, has high nitrification activity. However, nitrification in seawater RAS requires a long start-up time owing to the high salinity stress. Therefore, this study aimed to evaluate the nitrification characteristics and changes in the microbial community during the conversion of freshwater to seawater in a DHSreactor fed with ammonia-based artificial seawater. The total ammonia nitrogen concentration reached 1.0 mg-N⋅L 1 (initial concentration 10 mg-N⋅L 1) within 11 days of operation, and nitrate production was observed. The 16 S rRNA gene sequence of the DHS-retained sludge indicated that the detection rate of the ammonia-oxidizing archaeon Candidatus Nitrosocosmicus decreased from 23.9 % to 14.0 % and 25.8–17.6 % in the upper and lower parts of the DHS reactor, respectively, after the introduction of seawater. In contrast, the nitrite-oxidizing bacteria Nitrospira spp. increased from 0.1 % to 9.5 % and from 0.5 % to 10.5 %, respectively. The ammonia oxidation rates of 0.12 ±0.064 and 0.051 ±0.0043 mg-N⋅g-MLVSS 1⋅h 1 on the 37th day in the upper and bottom layers, respectively. Thus, nitrification in the DHS reactor performed well, even under high-salinity conditions with short operational days. This finding makes the transition from freshwater to saltwater fish in the RAS system simple and economical, and has the potential for early start-up of the RAS.Ítem Rapid detection of enterobacteria in wastewater treated by microalgal consortia using loop-mediated isothermal amplification (LAMP)(PeerJ Inc., 2024) Cameron, Henry; Bazaes, Jazmín; Sepúlveda, Claudia; Riquelme, CarlosIn 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.Ítem Whole-genome sequencing of a Janthinobacterium sp. isolatedfrom the Patagonian Desert(American Society For Microbiology, 2024) Cavanaugh, Nicole T.; Kumar, Girish; Reverdy Pearson, Alicyn; Colbert, Julia; Riquelme, Carlos; Hudson, André O.; Chai, Yunrong; Godoy Carter, VeronicaJanthinobacterium is a genus of Gram-negative environmental bacteria that survive extreme conditions by forming biofilms and producing pigments. Janthinobacterium sp. LS2A, an extremophile isolated from soil in the Chilean Patagonia, contains seven known biosynthetic gene clusters, including the purple pigment violacein, which may aid in its survival in harsh environments.