Selection Of Strains Research Articles

Bacteria-loaded biochar for the immobilization of cadmium in an alkaline-polluted soil.

The combination of biochar and bacteria is a promising strategy for the remediation of Cd-polluted soils. However, the synergistic mechanisms of biochar and bacteria for Cd immobilization remain unclear. In this study, the experiments were conducted to evaluate the effects of the combination of biochar and Pseudomonas sp. AN-B15, on Cd immobilization, soil enzyme activity, and soil microbiome. The results showed that biochar could directly reduce the motility of Cd through adsorption and formation of CdCO3 precipitates, thereby protecting bacteria from Cd toxicity in the solution. In addition, bacterial growth further induces the formation of CdCO3 and CdS and enhances Cd adsorption by bacterial cells, resulting in a higher Cd removal rate. Thus, bacterial inoculation significantly enhances Cd removal in the presence of biochar in the solution. Moreover, soil incubation experiments showed that bacteria-loaded biochar significantly reduced soil exchangeable Cd in comparison with other treatments by impacting soil microbiome. In particular, bacteria-loaded biochar increased the relative abundance of Bacillus, Lysobacter, and Pontibacter, causing an increase in pH, urease, and arylsulfatase, thereby passivating soil exchangeable Cd and improving soil environmental quality in the natural alkaline Cd-contaminated soil. Overall, this study provides a systematic understanding of the synergistic mechanisms of biochar and bacteria for Cd immobilization in soil and new insights into the selection of functional strain for the efficient remediation of the contaminated environments by bacterial biochar composite.

Characterisation of populations at risk of sub-optimal dosing of artemisinin-based combination therapy in Africa.

Selection of resistant malaria strains occurs when parasites are exposed to inadequate antimalarial drug concentrations. The proportion of uncomplicated falciparum malaria patients at risk of being sub-optimally dosed with the current World Health Organization (WHO) recommended artemisinin-based combination therapies (ACTs) is unknown. This study aims to estimate this proportion and the excess number of treatment failures (recrudescences) associated with sub-optimal dosing in Sub-Saharan Africa. Sub-populations at risk of sub-optimal dosing include wasted children <5 years of age, patients with hyperparasitaemia, pregnant women, people living with HIV, and overweight adults. Country-level data on population structure were extracted from openly accessible data sources. Pooled adjusted Hazard Ratios for PCR-confirmed recrudescence were estimated for each risk group from published meta-analyses using fixed-effect meta-analysis. In 2020, of the estimated 153.1 million uncomplicated P. falciparum malaria patients in Africa, the largest risk groups were the hyperparasitaemic patients (13.2 million, 8.6% of uncomplicated malaria cases) and overweight adults (10.3 million, 6.7% of uncomplicated cases). The estimated excess total number of treatment failures ranged from 0.338 million for a 98% baseline ACT efficacy to 1.352 million for a 92% baseline ACT efficacy. Our study shows that an estimated nearly 1 in 4 people with uncomplicated confirmed P. falciparum malaria in Africa are at risk of receiving a sub-optimal antimalarial drug dosing. This increases the risk of antimalarial drug resistance and poses a serious threat to malaria control and elimination efforts. Changes in antimalarial dosing or treatment duration of current antimalarials may be needed and new antimalarials development should ensure sufficient drug concentration levels in these sub-populations that carry a high malaria burden.

Microbiological and biotechnological study of yeast strains isolated during spontaneous fermentation of black grape variety ”Codrinschii”

An important task in the field of wine microbiology is obtaining local yeast strains that can easily adapt to the specific environmental conditions, ferment the carbohydrates in the must, and produce natural wines with high organoleptic qualities. This work presents the results of microbiological research related to the isolation and selection of local yeast strains for the production of dry red wines. The isolated yeast strains were tested to identify those that could be used to produce wines with typical characteristics. Based on the assessment of biochemical and technological indices of 15 yeast strains isolated from the must of the "Codrinschii" variety, 9 yeast strains were selected for the production of dry red wines.

Design analysis and construction of a biodiesel processing plant

This research focuses on the design, analysis, and construction of a biodiesel processing plant with the aim of improving global processes, control, and overall design efficiency. Biodiesel, a renewable energy source, offers environmental benefits and extends engine life. The study addresses the challenges associated with biodiesel usage, such as higher initial costs and potential engine issues, and proposes the use of waste vegetable oil to reduce processing costs. Various reactor designs from past studies are analyzed, emphasizing the need for effective mixing techniques. The research presents a novel prototype reactor and considers the selection of materials, stresses, strains, and insulation for each tank. Additionally, the study explores the use of different heating elements, including mica band heaters and immersion heaters, to achieve the required temperatures for transesterification. The findings also discuss the selection of gear motors and pumps for effective mixing and fluid transfer. The results of the construction and assembly of the biodiesel plant are presented, highlighting the inclusion of various accessories to enhance functionality. Finally, the research emphasizes the economic and environmental advantages of biodiesel production, considering energy consumption and cost savings in the Nigerian context.

1635. Assessing the Potential Reduction in Morbidity and Mortality Attainable by Delayed Influenza Vaccine Strain Selection

Abstract Background To allow time for production, seasonal influenza vaccine target strains must be chosen up to 8 months before the start of the influenza season. Antigenic drift during these months can lead to mismatch between the circulating and vaccine strains, negatively impacting vaccine effectiveness (VE). mRNA vaccines can be produced more quickly than standard vaccines, raising the possibility of delaying influenza vaccine strain selection by up to 3 months, thus potentially improving VE. This is especially important for the H3N2 subtype, which is generally more severe than other subtypes and causes most human infections. The potential reductions in morbidity and mortality attainable by delayed influenza vaccine strain selection, especially for H3N2 subtype, have not yet been examined. Methods We assessed the match between circulating and vaccine strains (only H3N2 subtype) using influenza phylogenetic data and associated predictions of antigenic distance (difference in log-2 HI titer) from 2011-2019 obtained from GISAID and analyzed using NextStrain. We then developed a mathematical model to estimate the potential reduction in symptomatic cases, hospitalizations, and mortality attainable by a 3-month delay in influenza vaccine strain selection. A direct estimation of final epidemic size, trained to historical data on influenza burden from the US Centers for Disease Control and Prevention, was used to parametrize the model. Results In 2011-2019, a 3-month delay in strain selection could have detected the emergence of antigenically distinct H3N2 strains ( &amp;gt; 2 predicted log-2 HI titer difference from the vaccine) on 3 occasions: Mar (June) 2012, Sep (Dec) 2014, and Sep (Dec) 2017 (Figure). Improved strain selection in 2012 and 2017 may have had only a limited impact: VE in the NH 2012-13 season remained high despite the suboptimal match, and circulation of influenza in the SH in 2018 was low. However, in 2014, improved strain selection could have yielded substantial benefits, with model-estimated reductions in hospitalizations and mortality between 15-20%. Conclusion Delayed seasonal influenza vaccine strain selection, made possible by mRNA vaccine technology, could improve vaccine strain match and potentially yield reductions in hospitalizations and mortality in some seasons. Disclosures Stephen M. Kissler, PhD, ModernaTx: Advisor/Consultant Keya Joshi, PhD, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds Nicolas Van de Velde, PhD, Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Nevena Vicic, MSc, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds Yoonyoung Park, ScD, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds Deborah Rudin, MD, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds Parinaz Ghaswalla, PhD, Moderna, Inc: Employee|Moderna, Inc: Stocks/Bonds

Using a dynamical model to study the impact of a toxoid vaccine on the evolution of a bacterium: The example of diphtheria

Vaccines are one of humankind's greatest weapons against infectious diseases. However, their usefulness is often questioned and the public tends to distrust vaccines. A mathematical model published in the early 2000s predicts the selection of more virulent strains of pathogens when populations are protected with imperfect vaccines, i.e., vaccines which reduce but do not entirely block pathogen transmission, such as toxoid vaccines. In this study, we built a disease-specific competition model to analyze the evolution of diphtheria's virulence under the pressure of a toxoid vaccine. Our results show that i) high vaccine coverage favors the emergence and increase prevalence of avirulent (or less virulent) strains of Corynebacterium diphtheriae (the etiologic agent of diphtheria) and ii) that competition between strains is crucial in the eradication of toxigenic strains when toxoid vaccines are used. We conclude that the use of toxoid vaccines could lead to disease eradication if the interaction between strains is taken into account. Our results could extend to biologically similar systems such as pertussis.

Mayaro virus pathogenesis and immunity in rhesus macaques.

Mayaro virus (MAYV) is a mosquito-transmitted alphavirus that causes debilitating and persistent arthritogenic disease. While MAYV was previously reported to infect non-human primates (NHP), characterization of MAYV pathogenesis is currently lacking. Therefore, in this study we characterized MAYV infection and immunity in rhesus macaques. To inform the selection of a viral strain for NHP experiments, we evaluated five MAYV strains in C57BL/6 mice and showed that MAYV strain BeAr505411 induced robust tissue dissemination and disease. Three male rhesus macaques were subcutaneously challenged with 105 plaque-forming units of this strain into the arms. Peak plasma viremia occurred at 2 days post-infection (dpi). NHPs were taken to necropsy at 10 dpi to assess viral dissemination, which included the muscles and joints, lymphoid tissues, major organs, male reproductive tissues, as well as peripheral and central nervous system tissues. Histological examination demonstrated that MAYV infection was associated with appendicular joint and muscle inflammation as well as presence of perivascular inflammation in a wide variety of tissues. One animal developed a maculopapular rash and two NHP had viral RNA detected in upper torso skin samples, which was associated with the presence of perivascular and perifollicular lymphocytic aggregation. Analysis of longitudinal peripheral blood samples indicated a robust innate and adaptive immune activation, including the presence of anti-MAYV neutralizing antibodies with activity against related Una virus and chikungunya virus. Inflammatory cytokines and monocyte activation also peaked coincident with viremia, which was well supported by our transcriptomic analysis highlighting enrichment of interferon signaling and other antiviral processes at 2 days post MAYV infection. The rhesus macaque model of MAYV infection recapitulates many of the aspects of human infection and is poised to facilitate the evaluation of novel therapies and vaccines targeting this re-emerging virus.

Efficacy of the Vaccine Candidate Based on the P0 Peptide against Dermacentor nitens and Ixodes ricinus Ticks.

The control of ticks through vaccination offers a sustainable alternative to the use of chemicals that cause contamination and the selection of resistant tick strains. However, only a limited number of anti-tick vaccines have reached commercial realization. In this sense, an antigen effective against different tick species is a desirable target for developing such vaccines. A peptide derived from the tick P0 protein (pP0) conjugated to a carrier protein has been demonstrated to be effective against the Rhipicephalus microplus, Rhipicephalus sanguineus, and Amblyomma mixtum tick species. The aim of this work was to assess the efficacy of this peptide when conjugated to the Bm86 protein against Dermacentor nitens and Ixodes ricinus ticks. An RNAi experiment using P0 dsRNA from I. ricinus showed a dramatic reduction in the feeding of injected female ticks on guinea pigs. In the follow-up vaccination experiments, rabbits were immunized with the pP0-Bm86 conjugate and challenged simultaneously with larvae, nymphs, and the adults of I. ricinus ticks. In the same way, horses were immunized with the pP0-Bm86 conjugate and challenged with D. nitens larva. The pP0-Bm86 conjugate showed efficacies of 63% and 55% against I. ricinus and D. nitens ticks, respectively. These results, combined with previous reports of efficacy for this conjugate, show the promising potential for its development as a broad-spectrum anti-tick vaccine.

A retrospective case-control study to evaluate the use of beta-lactam desensitization in the management of penicillin-allergic patients: a potential strategy for Antimicrobial Stewardship Programs.

Introduction: Penicillin allergy labels (PAL) are common in the hospital setting and are associated with worse clinical outcomes. Desensitization can be a useful strategy for allergic patients when alternative options are suboptimal or not available. The aim was to compare clinical outcomes of patients with PAL managed with antibiotic desensitization vs. those who received alternative non-beta-lactam antibiotic treatments. Methods: A retrospective 3:1 case-control study was performed between 2015-2022. Cases were adult PAL patients with infection who required antibiotic desensitization; controls were PAL patients with infection managed with an alternative antibiotic treatment. Cases and controls were adjusted for age, sex, infection source, and critical or non-critical medical services. Results: Fifty-six patients were included: 14 in the desensitization group, 42 in the control group. Compared to the control group, desensitized PAL patients had more comorbidities, with a higher Charlson index (7.4 vs. 5; p = 0.00) and more infections caused by multidrug-resistant (MDR) pathogens (57.1% vs. 28.6%; p = 0.05). Thirty-day mortality was 14.3% in the desensitized group, 28.6% in the control group (p = 0.24). Clinical cure occurred in 71.4% cases and 54.8% controls (p = 0.22). Four control patients selected for MDR strains after alternative treatment; selection of MDR strains did not occur in desensitized patients. Five controls had antibiotic-related adverse events, including Clostridioides difficile or nephrotoxicity. No antibiotic-related adverse events were found in the study group. In multivariate analysis, no differences between groups were observed for main variables. Conclusion: Desensitization was not associated with worse clinical outcomes, despite more severe patients in this group. Our study suggests that antibiotic desensitization may be a useful Antimicrobial Stewardship tool for the management of selected PAL patients.

Chitosan- and gallic acid-based (NPF) displayed antibacterial activity against three Pseudomonas spp. plant pathogens and boosted systemic acquired resistance in kiwifruit and olive plants.

Pseudomonas syringae pv. actinidiae (Psa), P. syringae pv. tomato (Pst) and P. savastanoi pv. savastanoi (Psav) are bacterial plant pathogens with worldwide impact that are mainly managed by the preventive application of cupric salts. These are dangerous for ecosystems and have favoured the selection of resistant strains, so they are candidates to be replaced in the next few years. Thus, there is an urgent need to find efficient and bio-based solutions to mitigate these bacterial plant diseases. Nanotechnology could represent an innovative way to control plant diseases, providing alternative solutions to the agrochemicals traditionally employed, thanks to the formulation of the so-called third-generation and nanotechnology-based agrochemicals. In this work, a novel nanostructured formulation (NPF) composed of cellulose nanocrystals (CNC) as carrier, high amylose starch (HAS) as excipient, and chitosan (CH) and gallic acid (GA) as antimicrobials, was tested at 2% in vitro and in vivo with respect to the three different Pseudomonas plant pathogens. In vitro agar assays demonstrated that the NPF inhibited ≤80% Psa, Pst and Psav. Moreover, the NPF did not decrease biofilm synthesis and it did not influence bacterial cells flocculation and adhesion. On plants, the NPF displayed complete biocompatibility and boosted the transcript levels of the major systemic acquired resistance responsive genes in kiwifruit and olive plants. This works provides novel and valuable information regarding the several modes-of-action of the novel NPF, which could potentially be useful to mitigate Psa, Pst and Psav infections even in organic agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Selection of Lactiplantibacillus plantarum strains as inoculant of rice straw fermentation and its fermentation characteristics

Selection of Lactiplantibacillus plantarum strains as inoculant of rice straw fermentation and its fermentation characteristics

Selection of Lactiplantibacillus plantarum strains as inoculant of rice straw fermentation and its fermentation characteristics

Selection of Lactiplantibacillus plantarum strains as inoculant of rice straw fermentation and its fermentation characteristics

Drift and shape-new insights into human immunity against influenza virus neuraminidase.

Influenza virus hemagglutinin mediates infection by binding sialic acids, whereas neuraminidase cleaves sialic acids to release progeny virions. Both are targets of protective antibodies, but influenza vaccine strain selection and antigen dose are based on hemagglutinin alone. Virus characterization using first infection ferret sera indicates that escape from hemagglutination inhibiting (HI) antibodies occurs more frequently and is not coordinated with escape from neuraminidase inhibiting (NI) antibodies. A key question addressed by Daulagala et al. (P. Daulagala, B. R. Mann, K. Leung, E. H. Y. Lau, et al., mBio 14:e00084-23, 2023, https://doi.org/10.1128/mbio.00084-23) is how this translates to humans who encounter multiple influenza viruses throughout life. Their cross-sectional study, using sera from a wide age range of participants and H1N1 viruses spanning 1977-2015, indicates that NI antibodies are more broadly cross-reactive than HI antibodies. Both HI and NI titers were highest against strains encountered in childhood indicating that both are shaped by priming exposures. The study further supports the development of NA-optimized vaccines.

Strain diversity in Saccharomyces cerevisiae thiamine production capacity

AbstractVitamin B1, also known as thiamine, is an important vitamin that, besides its role in human health, is converted to meat aromas upon exposure to high temperatures. Therefore, it is relevant for the production of vegan meat‐like flavours. In this study, we investigated 48 Saccharomyces cerevisiae strains for their thiamine production capacity by measuring the intracellular and extracellular vitamins produced in the thiamine‐free minimal medium after 72 h of growth. We found approximately an 8.2‐fold difference in overall thiamine yield between the highest and lowest‐producing strains. While the highest thiamine yield was 254.6 nmol/L, the highest thiamine‐specific productivity was 160.9 nmol/g DW. To assess whether extracellular thiamine was due to leakage caused by cell damage, we monitored membrane permeabilization using propidium iodide (PI) staining and flow cytometry. We found a good correlation between the percentage of extracellular thiamine and PI‐stained cells (Spearman's ρ = 0.85). Finally, we compared S. cerevisiae CEN.PK113‐7D (wild type [WT]) to three strains evolved in a thiamine‐free medium for their thiamine production capacity. On average, we saw an increase in the amount of thiamine produced. One of the evolved strains had a 49% increase in intracellular thiamine‐specific productivity and a biomass increase of 20% compared with the WT. This led to a total increase in thiamine yield of 60% in this strain, reaching 208 nmol/L. This study demonstrated that it is possible to achieve thiamine overproduction in S. cerevisiae via strain selection and adaptive laboratory evolution.

Phylogenetic identification of influenza virus candidates for seasonal vaccines.

The seasonal influenza (flu) vaccine is designed to protect against those influenza viruses predicted to circulate during the upcoming flu season, but identifying which viruses are likely to circulate is challenging. We use features from phylogenetic trees reconstructed from hemagglutinin (HA) and neuraminidase (NA) sequences, together with a support vector machine, to predict future circulation. We obtain accuracies of 0.75 to 0.89 (AUC 0.83 to 0.91) over 2016-2020. We explore ways to select potential candidates for a seasonal vaccine and find that the machine learning model has a moderate ability to select strains that are close to future populations. However, consensus sequences among the most recent 3 years also do well at this task. We identify similar candidate strains to those proposed by the World Health Organization, suggesting that this approach can help inform vaccine strain selection.

Selection and development of superior strains through functional trait-based approach in agarophytic red alga Gracilaria dura (Rhodophyta)

Aim: Gracilaria dura, a red agarophyte, is known for its high-quality agarose content and holds significant potential for commercial applications in aquaculture-related industries. The successful commercial utilization of seaweeds relies heavily on obtaining high-quality seed material with commercially valuable traits. Methodology: This study focuses on employing a functional trait-based approach to develop superior strains of G. dura for commercial aquaculture in India. Cultivation through an open sea farm, variations in growth, agar yield, pigments, antioxidant capacity, and primary productivity among the strains were observed. Results: The daily growth rate ranged from 0.5 to 3.5% per day, while pigment content exhibited variations in the Chlorophyll-a, R-Phycocyanin, and R-Phycoerythrin contents. Antioxidant capacity and gross primary productivity also displayed diverse ranges. From a total of 38 strains of G. dura, three were selected based on their growth and other functional traits, namely ADI0221201, VER0220090, and ADI0221202. Positive correlations were identified between growth and regeneration, as well as growth and Chl-a. Agar content showed a positive association with antioxidant capacity and productivity. 1H NMR analysis identified 12 metabolites as potential biomarkers for G. dura growth. Interpretation: All three selected strains hold promise for future commercial cultivation of Gracilaria dura. Furthermore, six additional strains were selected based on their higher growth and agar yield for targeted breeding and hybridization to enhance desirable traits. Key words: Agarophyte, Aquaculture, Functional traits, Growth, Gracilaria dura, Strain selection

Fermentation of brown seaweeds Alaria esculenta and Saccharina latissima for new product development using Lactiplantbacillus plantarum, Saccharomyces cerevisiae and kombucha SCOBY

Two seaweed species were examined (Alaria esculenta and Saccharina latissima) as a fermentation feedstock for the development of a beverage. Three microbial groups were selected for experimentation; a single-species bacterium; Lactiplantibacillus plantarum, a single-species yeast; Saccharomyces cerevisiae and a multi-species culture; kombucha SCOBY (Symbiotic Culture of Bacteria and Yeast). Results showed SCOBY cultures were more successful in fermenting A. esculenta than S. latissima due to the lowered glucose content (4.069 ± 0.174 mg / mL and 12.224 ± 2.249 mg / mL, respectively). Likewise, L. plantarum played a major role in fermenting S. latissima, over A. esculenta, resulting in a lowered pH in the former but not the latter (6.44 ± 0.040 and 4.825 ± 0.045, respectively). S. cerevisiae does not appear to have been suitable as a fermentation medium for these two seaweed species under these conditions due to the lack of pH lowering, glucose reduction and acid production. All treatments showed an increased production of lactic acid, especially the SCOBY treated samples, which is an indicator of fermentation. There is potential for optimization of the seaweed fermentation process through strain selection, fermentation conditions optimization (temperature, time, pH) and seaweed biomass pretreatment. Glutamic acid, the amino acid responsible for umami flavour, was found in greater quantities in the S. cerevisiae treated seaweed, indicating that fermentation using S. cerevisiae cultures may improve the umami flavour profile of a seaweed fermented beverage product. In order to see if the seaweed species used had an impact on the SCOBY microbial makeup, the DNA profiles of the two SCOBYs used were analyzed. There were significant differences between the two SCOBYs. The A. esculenta SCOBY showed slightly rarer species of fungi and the species abundance of fungi was greater than that of S. latissima SCOBY. Furthermore, the number of fungal operational taxonomic units (OTUs) in A. esculenta SCOBY was higher than that in S. latissima SCOBY. This study shows the potential of using brown seaweed species as a fermentation substrate to develop a novel, fermented beverage.

Gamma-Aminobutyric Acid (GABA) Producing Lactobacillus plantarum TSUB-17 and Probiotic Properties for Using as Probiotics Additive in Swine Feed

Due to the use of probiotics in animal husbandry has recently increased, the selection of high-quality probiotic strains is crucial. Since the uses of probiotics for animal feed supplements have to be applied at high doses of bacteria to be effective, the cultures’ safety is essential. This study successfully isolated the novel Lactobacillus sp. from swine fecal samples and identified it as L. plantarum TSUB-17. The L. plantarum TSUB-17 exhibited excellent probiotic properties, including 100 % resistance to 3 % acids and 1 % bile salts, and effectively inhibits pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella Typhimurium (isolated ESBL strain). L. plantarum TSUB-17 was also found to adhere to the intestinal wall and form a biofilm. Furthermore, the bacteria have revealed some unique properties of GABA production and detected the glutamate decarboxylase B (gadB) gene similar to L. brevis both in nucleotide sequence and secondary structure of the glutamate decarboxylase enzyme that was deduced from the nucleotide. The isolated bacteria also have antioxidant activity, and most importantly, the isolated strain was safe; it is non-hemolysis and susceptible to the tested antimicrobials. Therefore, L. plantarum TSUB-17 is suitable for further development as a probiotic additive in animal feed. HIGHLIGHTS This study successfully isolated Lactobacillus plantarum TSUB-17 with a high potential to develop as a probiotic for animals. The isolated bacterium has excellent properties: It tolerates high levels of acids and bile salts. It is effective against many pathogenic bacteria, produces gamma-aminobutyric acid (GABA) and shows high levels of antioxidant activity. Moreover, L. plantarum TSUB-17 is very safe due to its non-hemolytic strain and susceptibility to numerous antimicrobial drugs. GRAPHICAL ABSTRACT

Antibiotic-Resistant Bacteria in Environmental Water Sources from Southern Chile: A Potential Threat to Human Health

Antimicrobial resistance (AMR) is a critical global issue affecting public and animal health. The overuse of antibiotics in human health, animal production, agriculture, and aquaculture has led to the selection of antibiotic-resistant strains, particularly in Gram-negative bacteria. Mutations and horizontal gene transfer play a significant role in the development of antimicrobial resistance, leading to the reduced efficacy of current antibiotics. Today, AMR in bacteria and antibiotic-resistance genes (ARGs) are increasingly recognized in multiple environmental sources, including recreational and irrigation waters. This study aims to identify Gram-negative bacteria from surface aquatic reservoirs in southern Chile and assess their susceptibility to clinically relevant antibiotics. Water samples were collected from four lakes, five rivers, one waterfall, and one watershed in southern Chile to isolate environmental Gram-negative bacilli (GNB). API-20E and MALDI–TOF were employed for bacterial identification. Kirby–Bauer disc diffusion tests and multiplex PCR were performed to determine their susceptibility profile. A total of 26 GNB strains were isolated from environmental water samples, predominantly belonging to the Pseudomonas (n = 9) and Acinetobacter (n = 7) genera. Among these strains, 96.2% were resistant to ampicillin and cefazoline, while 26.9% and 34.6% showed resistance to ceftazidime and cefepime, respectively. Additionally, 38.5% exhibited resistance to colistin. Two Enterobacter cloacae strains obtained from Cachapoal River (sixth region) and Villarrica Lake (ninth region), respectively, presented a multidrug-resistant (MDR) phenotype and carried at least two extended-spectrum β-lactamase (ESBL) genes. Thus, antibiotic-resistant GNB and ARGs were found in natural water reservoirs, raising concerns about the dissemination of resistance determinants among potentially pathogenic bacteria in environmental microbial communities.

Strain selection of red algae Kappaphycus alvarezii (Doty) Doty farmed using different methods in Tablolong Waters, Kupang Regency-East Nusa Tenggara Province

The main problem is facing in farming red algae Kappaphycus spp. in Kupang Regency are decreasing quality of seeds and the infection of ice-ice disease. This research aimed to analyze the growth of different strains of K. alvarezii farmed using different methods, and analyze which strains of K. alvareziii have high resistance to ice-ice disease. This research was carried on August to November 2020 in Tablolong waters, Kupang Regency. The strains used were Sacol from Sulamu and Semau, Tambalang (tissue culture) from Rote Island, and Cottonii strain from Pasir Panjang. The farming methods used were the Longline and Off-Bottom. The main data taken were wet weight and incidence as well as infection intensity of the disease. The study found that growth rates varied based on the strains and farming methods. Based on the strain, the Sacol strain from Sulamu gave a higher growth than the others. This strain grew and reached an average weight of 1087.5 grams at week 7; with an average specific growth of 4.87% per day. Based on the method, the longline method gave better growth compared to the off-bottom method. Regarding ice-ice disease, the Sacol strain from Sulamu gave higher resistance to disease compared to the other strains, with an average incidence of 27.26% and an infection intensity of 2.81%. The longline method provides higher disease resistance than the off-bottom method.