Laboratory Culture Research Articles

Metabolic labour division trade-offs in denitrifying microbiomes

Abstract Division of metabolic labour is a defining trait of natural and engineered microbiomes. Denitrification – the stepwise reduction of nitrate and nitrite to nitrogenous gases – is inherently modular, catalysed either by a single microorganism (termed complete denitrifier) or by consortia of partial denitrifiers. Despite the pivotal role of denitrification in biogeochemical cycles and environmental biotechnologies, the ecological factors selecting for complete versus partial denitrifiers remain poorly understood. In this perspective, we critically review over 1500 published metagenome-assembled genomes of denitrifiers from diverse and globally relevant ecosystems. Our findings highlight the widespread occurrence of labour division and the dominance of partial denitrifiers in complex ecosystems, contrasting with the prevalence of complete denitrifiers only in simple laboratory cultures. We challenge current labour division theories centred around catabolic pathways, and discuss their limits in explaining the observed niche partitioning. Instead, we propose that labour division benefits partial denitrifiers by minimising resource allocation to denitrification, enabling broader metabolic adaptability to oligotrophic and dynamic environments. Conversely, stable, nutrient-rich laboratory cultures seem to favour complete denitrifiers, which maximise energy generation through denitrification. To resolve the ecological significance of metabolic trade-offs in denitrifying microbiomes, we advocate for mechanistic studies that integrate mixed-culture enrichments mimicking natural environments, multi-meta-omics, and targeted physiological characterisations. These undertakings will greatly advance our understanding of global nitrogen turnover and nitrogenous greenhouse gases emissions.

In Vitro Selection Of Rice Somaclonal Variants For Salt Tolerance

An experiment was conducted at the Advanced Plant Breeding and Tissue Culture Laboratory of Bangabandhu Sheikh Mujibur Rahman Agricultural University to evaluate the effects of NaCl on rice callus induction and plant regeneration, along with genetic variability assessment through molecular markers. Dehusked seeds of five distinct rice genotypes (Dakshahi, Gondhakasturi, Guamasuri, Duksail, and Khazar) were put on MS medium supplemented with five levels (0, 0.2, 0.4, 0.6 and 0.8%) of NaCl. Developed calli were placed in MS medium for regeneration around 3-6 weeks later. Callus induction and plant regeneration declined with the increase of salinity levels. Dakshahi outperformed the other cultivars in both parameters at different salt concentrations, and it was the only cultivar with callus and regenerated plants at 0.08% NaCl concentrations. To amplify the genomic DNA of parents and somaclones of different varieties, five random amplified polymorphic DNA (RAPD) primers were used. Polymorphic bands were visible in OPD-07 primer. Dakshahi and Khazar were found to have the maximum genetic diversity (0.941). The genetic similarity coefficients between lines demonstrate that the degree of genetic diversity within rice genotypes was quite distinct. The cluster analysis grouped five genotypes into two clusters. The presence of genetic variation in the somaclones of Guamasuri implies the potential of RAPD markers in assessing genetic diversity and validating somaclonal variation. Also, Dakshahi demonstrating the highest tolerance for NaCl stress in both callus induction and plant regeneration, making it a promising candidate for salt-tolerant rice breeding in future. Bangladesh J. Agri. 2024, 49(2): 16-30

Anti-bacterial efficacy of Boron Nanosheet against clinical isolates and its in vivo toxicity assessment using Artemiasalina.

Microbes have been increasing their potential against newly developed drugs and antibiotics daily. The increased microbial drug resistance is still a challenging societal inconvenience. 2D nanomaterials, such as graphene, fascinate researchers with their unique physical and chemical properties and have a major role in current science and technology. Nowadays, researchers have been replacing graphene with its analogous 2D material, borophene, which is a single layer of boron with a honeycomb plane. Boron nanosheets which are theoretically investigated, have been synthesized by various top-down and bottom-up approaches. Our study focuses on synthesizing boron-based material from the precursor MgB2 which possesses a honeycomb boron structure with sandwiched Mg atoms. The Mg atoms have been selectively removed using the chelating agents at alkaline pH. The synthesized boron nanosheets have been characterized by FT-IR, Raman, XRD, FESEM, EDS, and TGA. The formation of B-H-B, B-B and B-O bond is confirmed by FT-IR and Raman spectra. It is also evident from XPS spectra which possess B1s spectra at 193eV. The efficient chelation and exfoliation is confirmed by EDS and FESEM analysis which shows the presence of boron and trace amount of Mg with bark like projections. Though there are several studies on antibacterial activity of compounds, generally the studies are with laboratory cultures of bacterial strains. Clinical studies offer more valid results and are very sparse in literature. The use of clinical strains in the present study is one of the novelty. It has also been analyzed for its anti-bacterial activity against clinical strains of B. subtilis, S. aureus, E. coli, and K. pneumonia. Boron nanosheets possess an enhanced zone of inhibition (8mm, 11mm) against clinical strains of B. subtilis where the micro dilution studies show MIC and MBC values as 125μg and 62.5μg. The in vivo toxicity studies carried out using Brine Shrimp Lethality Assay reveal higher LC50 values of boron nanosheets (>1mg/ml), which in turn portrays its non-toxic nature. Thus, the synthesized boron nanosheets are toxic to multidrug-resistant B. subtilis where it is non-toxic to mammalian cells. Thus, the study could advance the applications of borophene in biomedical applications.

The Effect of Foliar Fertilizers as Substitution Media on The Growth of Chrysanthemum morifolium Shoot by In Vitro Culture

The production of chrysanthemum plants in large quantities can be obtained by in vitro growth of chrysanthemums. The growth media that is often used is MS media which has a relatively high price. Therefore, a substitution medium that has a relatively affordable price is needed in the form of foliar fertilizer media with coconut water and ambon bananas added. This study aims to examine the best medium that can be used for in vitro chrysanthemum growth. The research was carried out in June-September 2020 at the In Vitro Culture Laboratory, Faculty of Agriculture, University of Muhammadiyah Yogyakarta. The research was carried out by a single-factor experimental method with 7 treatments and each had 5 replicates and each replicate consisted of 3 samples arranged with a Complete Random Design (RAL). The treatment that was experimented with was the use of foliar fertilizers in the form of Growmore and Hyponex Green with the addition of coconut water and bananas. The concentrations of Growmore foliar fertilizer given were 3 g/l, 4 g/l, and 5 g/l. The concentrations of Green Hyponex foliar fertilizer given were 3 g/l, 4 g/l, and 5 g/l. The results of the research showed that foliar fertilizer added with coconut water and banana ambon could be used as a substitution medium for MS media in chrysanthemum growth in vitro. The use of Growmore 4 g/l foliar fertilizer shows the best hail against the tall growth of chrysanthemum shoots in vitro

Стійкість мохів із фонових і антропогенно трансформованих територій до водного дефіциту

The tolerance to water deficit protonema of vegetative and generative clones of mosses Bryum argenteum Hedw., Funaria hygrometrica Hedw. and Barbula unguiculata Hedw. from the background (Lviv city “Pohulyanka” forest park) and anthropogenically disturbed areas of the Yaziv sulfur deposit (Lviv region, Yavoriv district) and the waste dump of the Chervonograd mining and industrial district (ChGPK). The laboratory culture was grown on Knopp’s agar medium, creating a water deficit by adding 1–5 % polyethylene glycol (PEG) to the medium. It was established that the vegetative clones of the investigated mosses from different local vegetation in the background and anthropogenically transformed territories are more tolerant to lack of moisture than the generative ones. The most resistant were Bryum argenteum sods from the top of the southern slope of the sulfur mining dump, which on the medium with 2 % polyethylene glycol (PEG) had the largest diameter and the largest number of gametophores per sod compared to the samples from the wetter localities of the northern slope of the dump. Vegetative clones from different local vegetation from background and anthropogenically disturbed areas showed different sensitivity to water deficit. The plants from the dumps were characterized by a higher growth rate of regenerants and formed more gametophores on the medium with PEG than the samples from Lviv. It was established that the tolerance of vegetative and generative clones of mosses B. argenteum, F. hygrometrica and B. unguiculata to moisture deficit depends on the age of the plants, the concentration of PEG and the duration of its action, as well as the life strategy of the species. It is shown that mosses, due to successful vegetative reproduction with a short development cycle, which can partially replace generative reproduction in stressful conditions, in particular lack of moisture, better adapt to conditions of water deficit in post-technological territories of the Yaziv sulfur deposit and rock dump of coal mining of ChHPK.

296. MDR Risk Index: Multidrug-Resistant Bacteria Probability Score for General Hospitals

Abstract Background This research endeavors to shed light on the intricate relationship between hospitalization dynamics and the probability of acquiring multidrug-resistant bacteria (MDR) by introducing a predictive tool, the Multidrug-Resistant Bacteria Probability Score.Figure 1.Estimated Risk of MDR (Multidrug-Resistant Bacteria): Point Estimates and 95% Confidence Intervals. Methods We processed cultures in the hospital laboratory using automated systems and/or microdilution methods, adhering to the BR-cast guidelines. We utilized a logistic regression model to analyze four predictive variables for MDR: length of hospitalization until the collection of biological material (days), previous hospitalization (yes/no), duration of previous hospital stays (days), and admission to the Intensive Care Unit (ICU) (yes/no). The assessment focused on 7 outcomes: MDR (any type), resistance to Meropenem (RMER), production of Klebsiella pneumoniae carbapenemase (KPC), production of Extended Spectrum Beta-Lactamase (ESBL), resistance to Polymyxin (RPOL), Vancomycin-resistant Enterococci (VRE), and Methicillin-resistant Staphylococcus aureus (MRSA).Figure 2.Logistic Regression Models Estimating MDR Risk: Results for Each Type of MDR Bacteria. Results A total of 4,247 biological samples were collected from Nov/2022 to Nov/2023: Urine (46%), Blood (12%), Tissue Fragments (11%), Bronchoalveolar Lavage (6%), Perianal Swabs (6%), Tracheal Aspirates (4%), Nasal Swabs (3%), Abdominal Fluid (2%), Tips of Central or Umbilical Catheters (2%), Wound Secretions (1%), and Other (3%). Approximately one-third (35%) of the samples were identified as MDR. Unadjusted MDR risk: 9% RMER, 5% KPC, 8% ESBL, 1% RPOL, 3% VRE, and 4% MRSA (Fig. 1). From the seven outcomes modeled, it was possible to successfully predict five of them (Fig. 2), yielding good results in terms of predictive capability (Fig. 3). However, the modeling was unsuccessful for MRSA and ESBL. Figure 4 shows simulations of MDR risk.Figure 3.ROC Curves for the Five Successful Models Predicting Multidrug-Resistant Bacteria (MDR). Conclusion The duration of hospitalization prior to the collection of biological material emerges as a crucial metric, encapsulating the temporal dimension of patient exposure to potential sources of infection. All five predictive models can be effectively integrated into the patient’s electronic health record. This integration enables the timely prediction of multidrug-resistant (MDR) infections, facilitating the implementation of targeted preventive measures based on the assessed risk level.Figure 4.Simulation of MDR Risk Evolution Over Hospitalization Time: Curves Representing MDR Risk by Patient Type Disclosures All Authors: No reported disclosures

P-2145. Candida blankii: An Emerging Threat among Hospitalized Neonates of Bangladesh

Abstract Background Invasive fungal infections (IFIs) cause serious complications and fatality. Despite the severity of such magnitude, the true burden of these infections remains unclear. In LMICs like Bangladesh, there is a lack of surveillance mechanisms to understand the burden of IFIs. Candida blankii (C. blankii) is an emerging clinical pathogen with first reported human infection in 2014 and limited global reports of clinical infection since then. This study aims to investigate the burden on C. blankii along with other IFIs among hospitalized neonates in Bangladesh. Methods Since July 2022, a hospital-based IFI surveillance has been ongoing in the neonatal ICU of a tertiary level hospital in Bangladesh. From then until April 2024, 224 patients were enrolled, who were suspected of have IFIs based on predefined inclusion and exclusion criteria. Blood and endotracheal aspirate samples were collected and sent to the laboratory for microscopy, culture and identification using Vitek 2 and Vitek MS automated system. Additionally, antifungal susceptibility testing (AFST) was performed using the Vitek2 system. Results Median age of the enrolled neonates were 17 days (IQR:12-21); 67% of them were male. Notably, 76% of these neonates had positive blood cultures for at least one fungal organism. Kodamaea ohmeri was the most frequently identified fungus (52 cases), followed by Candida cifferi (45) and the emerging fungus C. blankii (36). There were only two cases of Cryptococcus laurentii along with other candida species. Mortality rates were highest among neonates infected with Candida cifferi (67%), followed by C. blankii (45%) and Kodamaea ohmeri (36%). Worryingly, C. blankii exhibited high resistance to Amphotericin B (97%) and Voriconazole (69%), potentially limiting effective treatment options. High Antifungal Resistance Conclusion This ongoing surveillance identified a high prevalence of IFIs, particularly caused by the emerging fungus C. blankii. Further research is necessary to elucidate the potential sources and transmission pathways of C. blankii to design targeted interventions to effectively control this emerging threat in this vulnerable population. The surveillance team is actively working with the hospital authorities to identify potential sources and implement strategies to minimize such infections. Disclosures All Authors: No reported disclosures

Before and Besides Werktreue: (Re)inventing Operatic Staging at the 1930s Maggio Musicale Fiorentino

Abstract This article examines the role played by the Maggio Musicale Fiorentino as a kind of cultural laboratory for experiments in operatic staging in 1930s Italy. Founded in 1933, Florence's opera and arts festival was a key testing ground for ‘modern’ approaches both to set and costume design and to opera direction, two areas in which northern Europe (especially Germany) is normally held to have led the way, and through which the Maggio helped to reinvent Italian mise-en-scène as an act of independent, artistic creation. Setting the festival's overall project in the context of 1930s aesthetic, philosophical, and cultural debates about theatre, opera, and cinema, and drawing on a rich archive of as-yet-unexplored primary source materials, the article retraces an intellectual and cultural history of Italian staging c. 1930 that resonates productively with several present-day critical and scholarly concerns: from changing attitudes to the nineteenth-century operatic canon, to the early stirrings of Regietheater, to the intertwining histories of opera and film.

DMEM and EMEM are suitable surrogate media to mimic host environment and expand leptospiral pathogenesis studies using in vitro tools.

Pathogenic Leptospira species can survive and thrive in a wide range of environments. Distinct environments expose the bacteria to different temperatures, osmolarities, and amounts and sources of nutrition. However, leptospires are mostly cultured, in a laboratory setting under in vitro conditions that do not reflect natural environments. This constraint on laboratory cultures limits the applicability of in vitro studies to the understanding of even simple pathogenic processes. Here we report, investigate, and identify a medium and conditions that mimic the host environment during leptospirosis infection, expanding the available in vitro tools to evaluate leptospiral pathogenesis. We quantified genome-wide gene expression of pathogenic Leptospira interrogans cultured in different in vitro media compositions (EMJH, DMEM, EMEM, and HAN). Using EMJH as standard, we compared gene expression in these compositions to genome-wide gene expression gathered in a host environment: whole blood (WB) of hamsters after infection with pathogenic leptospires. Leptospires cultured in DMEM and EMEM media shared 40% and 47% of all differentially expressed genes (DEGs) of leptospires present within WB (FDR<0.01), while leptospires cultured in HAN media only shared 20% of DEGs with those from WB. Furthermore, gene and pathway expression of leptospires cultured on DMEM and EMEM media exhibited a better correlation with leptospires grown in WB, including promoting expression of a similar leptospiral lipid A profile to the one identified directly in host tissues. Taken together, these results indicate that commercial cell-culture media EMEM or DMEM are better surrogates for in vivo pathogenic studies than EMJH or HAN media in Leptospira . These alternative culture conditions, using media that are a standard supply worldwide, provide a reproducible and cost-effective approach that can accelerate research investigation and reduce the number of animal infections necessary for basic research of leptospirosis.

Importance, structure, cultivability, and resilience of the bacterial microbiota during infection of laboratory-grown Haematococcus spp. by the blastocladialean pathogen Paraphysoderma sedebokerense: evidence for a domesticated microbiota and its potential for biocontrol.

Industrial production of the unicellular green alga Haematococcus lacustris is compromised by outbreaks of the fungal pathogen Paraphysoderma sedebokerense (Blastocladiomycota). Here, using axenic algal and fungal cultures and antibiotic treatments, we show that the bacterial microbiota of H. lacustris is necessary for the infection by P. sedebokerense and that its modulation affects the outcome of the interaction. We combined metagenomics and laboratory cultivation to investigate the diversity of the bacterial microbiota associated to three Haematococcus species and monitor its change upon P. sedebokerense infection. We unveil three types of distinct, reduced bacterial communities, which likely correspond to keystone taxa in the natural Haematococcus spp. microbiota. Remarkably, the taxonomic composition and functionality of these communities remained stable during infection. The major bacterial taxa identified in this study have been cultivated by us or others, paving the way to developing synthetic communities to experimentally explore interactions within this tripartite system. We discuss our results in the light of emerging evidence concerning the structuring and domestication of plant and animal microbiota, thus providing novel experimental tools and a new conceptual framework necessary to enable the engineering of Haematococcus spp. microbiota toward the biocontrol of P. sedebokerense.

Optimizing Early Growth of Laminaria hyperborea in Controlled Settings: A Pathway to Improved Restoration Efforts

Laminaria hyperborea, a key species in marine forest ecosystems, is experiencing pressure at its southern distribution limit in northern Portugal due to climate change and human-induced stressors. The ongoing degradation of marine forests highlights the need for effective restoration strategies to protect biodiversity and maintain the essential services provided by these habitats. Cultivation of juvenile kelps in laboratory settings is a common approach shared across multiple strategies aimed at supporting reforestation efforts; however, the specific cultivation process for L. hyperborea remains largely underexplored. In this study, we tested two seeding densities to optimize the production of L. hyperborea recruits for reforestation initiatives. We assessed the effects of seeding density on juvenile development by measuring both area coverage and length. Our findings revealed that higher seeding density initially promoted greater area coverage (e.g., 8.69 ± 0.38 cm2 vs. 3.35 ± 0.27 cm2) but reduced the length of individual recruits over time (e.g., 0.26 ± 0.0026 cm vs. 0.39 ± 0.003 cm at T3). This suggests that increased competition for resources at high densities limits individual growth. In contrast, lower densities produced larger, more robust individuals (e.g., 0.50 ± 0.004 cm vs. 0.262 ± 0.003 cm at T4), which may enhance post-transplantation survival in challenging environmental conditions. This suggests that utilizing lower seeding densities may improve individual growth while decreasing overall resource use and maintenance needs, promoting a more sustainable cultivation process and minimizing impacts on donor populations. However, further research is essential to refine the cultivation protocols and fully understand the variables influencing juvenile kelp development. Improving all phases of the restoration process, from laboratory cultivation to field deployment, will be critical for reducing costs, streamlining logistics, and ensuring the scalability of future kelp restoration efforts.

Isolation of Dental Caries Bacteria from Dental Plaque

Background : Dental caries stands out as a highly prevalent and preventable condition, identified as the leading contributor to oral discomfort and tooth loss. This condition represents a significant public health challenge that obstructs the attainment and preservation of oral health across all age demographics. The WHO has indicated that the global issue of oral disease continues to exist, even with significant advancements in the oral health of populations in various countries. Aim of study : Isolation of Dental Caries Bacteria from Dental Plaque and detection Pattern of resistance to common antibiotics in dental clinics. Methodology : Specimens collection include 75 clinical swabs (45 Male and 25 Female) isolated from dental caries patients who were admitted to Al-Kafeel teaching clinic and outpatient from dentist clinic in AL-Najaf City between November 2022 to January 2023 with age group between 30-70 years. All the specimens were labeled and transported Immediately by sterile transport swabs to the laboratory for Culture and Identification. For each patient, medical records were reviewed, which including name, gender, age, address, hospitalization, and antibiotic receiving. and immediately transport to the old . Results : The study comprised of 75 patients with dental caries , 45 patients were male while 30 patients were female , The swabs taken from dental clinics have been showed that 64 (85.3%) of specimens were gram positive bacteria and only 11 specimens (14.7%) were gram negative bacteria. The result showed that about 64 specimens from totally 75 were gram positive and the most common species were: Streptococcus mutans 20 (26.66%) , Staphylococcus aureus 15 (20%), Lactobacilli 10 (13.33%) , Staphylococcus species 8 (10.66%) , Streptococcus species 5 (6.66%) , Enterococcus faecalis 4(5.33%) , Bacillus species 2 (2.66%) and Micrococcus species 2 (2.66%). Gram negative bacteria that isolated from dental caries were only 11 . The bacterial species were : E. coli 3 (4%), K. pneumonia 2 (2.66%) , P. aeruginosa 2 (2.66%), Moraxella 1 (1.33%) and Acinetobacter baumannii 1 (1.33%). Tow specimens were unknown (2.66%) , Vitek 2 system had no results.

Optimizing Growth Conditions and Biochemical Properties of Chondracanthus acicularis (Rhodophyta) in Laboratory Settings

This study aimed to evaluate the laboratory cultivation of Chondracanthus acicularis, focusing on key environmental parameters such as nutrient levels and light exposure. The results provide insights into the optimal growth conditions and biochemical composition of C. acicularis, which are crucial for its sustainable exploitation in industrial applications. Significant differences in the relative growth rate (RGR) and productivity (Y) were found between the different treatments. Seaweed grown on Provasoli (PES) Medium with white LED light and red LED light showed the best growth rates. Negative growth was observed in treatments with Nutribloom plus®, and blue LED light. The proximate composition analysis revealed a high moisture content across all treatments, with significant differences in ash and organic matter content between the treatments. The use of LED light played a crucial role in optimizing growth by influencing photosynthetic efficiency and pigment production. The proximate composition varied significantly between treatments, especially ash and organic matter. Light and nutrient conditions also influenced pigmentation and colour characteristics, with significant changes in phycoerythrin, phycocyanin, and chlorophyll concentration. PES treatments consistently showed the highest colour variation. These findings highlight the influence of environmental conditions on seaweed growth, productivity, pigmentation, and proximate composition, and provide valuable insights for optimized cultivation strategies.

'Nomadic' Hematopoietic Stem Cells Navigate the Embryonic Landscape.

Hematopoietic stem cells are a unique population of tissue-resident multipotent cells with an extensive ability to self-renew and regenerate the entire lineage of differentiated blood cells. Stem cells reside in a highly specialized microenvironment with surrounding supporting cells, forming a complex and dynamic network to preserve and maintain their function. The survival, activation, and quiescence of stem cells are largely influenced by niche-derived signals, with aging niche contributing to a decline in stem cell function. Although the role of niche in regulating hematopoiesis has long been established by transplantation studies, limited methods in observing the process in vivo have eluded a detailed understanding of the various niche components. Danio rerio (zebrafish) has emerged as a solution in the past few decades, enabling discovery of cellular interactions, in addition to chemical and genetic factors regulating HSCs. This review reiterates zebrafish as a suitable model for studies on vertebrate embryonic and adult hematopoiesis, delving into this temporally and spatially dissected multi-step process. The critical role played by epigenetic regulators are discussed, along with contributions of the various physiological processes in sustaining the stem cell population. Stem cell niche transcends mere knowledge acquisition, assuring scope in cell therapy, organoid cultures, aging research, and clinical applications including bone marrow transplantation and cancer. A better understanding of the various niche components could also leverage therapeutic efforts to drive differentiation of HSCs from pluripotent progenitors, sustain stemness in laboratory cultures, and improve stem cell transplantation outcomes.

Ultrafast enzyme-responsive hydrogel for real-time assessment and treatment optimization in infected wounds

Monitoring wound infection and providing appropriate treatment are crucial for achieving favorable outcomes. However, the time-consuming nature of laboratory culture tests may delay timely intervention. To tackle this challenge, a simple yet effective HDG hydrogel, composed of hydrogen peroxide (H₂O₂), dopamine, and GelMA polymer, is developed for the ultrafast detection and treatment of Staphylococcus aureus (SA) infections. The HDG hydrogel detects SA by exploiting its secreted catalase to catalyze H₂O₂, producing oxygen, which in turn accelerates the polymerization of colorless dopamine into deep brown polydopamine (PDA). The bacterial detection process takes only 10 min with high sensitivity, and the results can be readily recognized by the naked eye or quantified using a cell phone-based digital analysis. Moreover, the HDG hydrogel provides a dual antibacterial mechanism through chemical and photothermal therapies via the generated PDA, significantly improving bacterial clearance. In animal experiments, the HDG hydrogel demonstrated promising capabilities in monitoring and eliminating bacteria, enhancing collagen deposition, reducing inflammation, and promoting the healing of infected wounds. This multifunctional design offers an enzyme-responsive strategy for the rapid assessment and management of infections, simplifying infection evaluation and facilitating the development of advanced wound dressings.Graphical

Effects of Different Types of Microplastics on Cold Seep Microbial Diversity and Function.

The massive production and widespread use of plastics have resulted in a growing marine plastic pollution problem. Cold seep ecosystems are maintained by microorganisms related to nitrogen and carbon cycling that occur in deep-sea areas, where cold hydrocarbon-rich water seeps from the ocean floor. Little is known about plastic pollution in this ecosystem. To fill this knowledge gap, we collected sediment and seawater samples from the Haima cold seep and conducted laboratory cultivation experiments, simulating in situ environmental conditions. Environmental factors and microbial genetics were analyzed at different stages over a 2-month cultivation period. Our main conclusions are as follows: (1) When microplastics (MPs) were added to sediment and seawater environments, the microbial communities most closely resembled those of the original habitat. The changes in the plastisphere communities were mainly associated with the culture time. (2) The co-occurrence network of the plastisphere was more fragile than that of environments. (3) Multiple environmental factors determined the community composition, whereas a small number of environmental variables drove the community function. MPs affected nitrogen cycling and methane metabolism and might aggregate pathogenic species. This work provides a better perspective of the effect of MPs on the community structure and function in cold seeps.

A plasmid with the bla CTX-M gene enhances the fitness of Escherichia coli strains under laboratory conditions.

Antimicrobial resistance (AMR) is a major threat to global public health that continues to grow owing to selective pressure caused by the use and overuse of antimicrobial drugs. Resistance spread by plasmids is of special concern, as they can mediate a wide distribution of AMR genes, including those encoding extended-spectrum β-lactamases (ESBLs). The CTX-M family of ESBLs has rapidly spread worldwide, playing a large role in the declining effectiveness of third-generation cephalosporins. This rapid spread across the planet is puzzling given that plasmids carrying AMR genes have been hypothesized to incur a fitness cost to their hosts in the absence of antibiotics. Here, we focus on a WT plasmid that carries the bla CTX-M 55 ESBL gene. We examine its conjugation rates and use head-to-head competitions to assay its associated fitness costs in both laboratory and wild Escherichia coli strains. We found that the wild strains exhibit intermediate conjugation levels, falling between two high-conjugation and two low-conjugation laboratory strains, the latter being older and more ancestral. We also show that the plasmid increases the fitness of both WT and lab strains when grown in lysogeny broth and Davis-Mingioli media without antibiotics, which might stem from metabolic benefits conferred on the host, or from interactions between the host and the rifampicin-resistant mutation we used as a selective marker. Laboratory strains displayed higher conjugation frequencies compared to WT strains. The exception was a low-passage K-12 strain, suggesting that prolonged laboratory cultivation may have compromised bacterial defences against plasmids. Despite low transfer rates among WT E. coli, the plasmid carried low fitness cost in minimal medium but conferred improved fitness in enriched medium, indicating a complex interplay between plasmids, host genetics and environmental conditions. Our findings reveal an intricate relationship between plasmid carriage and bacterial fitness. Moreover, they show that resistance plasmids can confer adaptive advantages to their hosts beyond AMR. Altogether, these results highlight that a closer study of plasmid dynamics is critical for developing a secure understanding of how they evolve and affect bacterial adaptability that is necessary for combating resistance spread.

Pseudomonas aeruginosa alkyl quinolone response is dampened by Enterococcus faecalis.

While we now appreciate that many infections are polymicrobial, we understand little of the specific actions between a given set of microbes to enable combinatorial survival and pathogenesis. The bacteria Pseudomonas aeruginosa and Enterococcus faecalis are both prevalent pathogens in wound, urinary tract, and bacteremic infections. While P. aeruginosa often kills other species in standard laboratory culture conditions, we present here that E. faecalis can be reliably co-cultured with P. aeruginosa. We specifically detail that ornithine produced by E. faecalis reduces the Pseudomonas quinolone signal response of P. aeruginosa. This reduction of the Pseudomonas quinolone signal response aids E. faecalis growth.

Determination of the genetic dimension of Pseudomonas stutzeri which of nitrogen-fixation bacteria in a random PCR method

Bacteria play an important role in fixing atmospheric nitrogen and converting it into compounds that can be used by plants. Due to the importance of this topic, this type of bacteria was chosen, and its genetic dimension was studied. The nitrogen-fixing strain of Pseudomonas stutzeri, or those that have already been positively identified, should be collected from the wild or from laboratory cultures. Pseudomonas stutzeri strain was collected and their genomic DNA was extracted. This can be done using regular methods for extracting DNA. The purpose of this research is to generate a diverse panel of PCR amplification primers. Primers chosen at random are short sequences of nucleotides that can bind to various locations in the bacterial genome. These primers can be used to initiate polymerase chain reaction (RPCR) amplification at a high number of random positions within the DNA, allowing researchers to probe a wide range of genes. Fifteen different bundles, ranging in size from 200 to 3000 base pairs, were recorded. Thirteen differential bundles of 350, 425, 600, 650, 700, 800, 950, 1000, 1300, 1400, 1500, 1700, and 3000 base pairs are featured by the inclusion of two public bundles of 200 and 2000. Fifteen different bundles, ranging in size from 200 to 3000 base pairs, were recorded. Thirteen differential bundles of 350, 425, 600, 650, 700, 800, 950, 1000, 1300, 1400, 1500, 1700, and 3000 base pairs are featured by the inclusion of two public bundles of 200 and 2000.

ОТВЕТНЫЕ РЕАКЦИИ HYALELLA AZTECA НА ДЕЙСТВИЕ ЛАНТАНА В УСЛОВИЯХ ХРОНИЧЕСКОГО ЭКСПЕРИМЕНТА

The responses of the laboratory culture Hyalella azteca to the effect of lanthanum sulfate solutions in the concentration range of 0.16–160 μmol/l under conditions of a chronic trial were studied. It was shown that the mortality of H. azteca increased with an enhance in the concentration of La3+ in the solution. A consistent increase in the concentration of La3+ led to a natural raise in food consumption. The most informative test function in assessing the toxicity of La3+ is the length and weight of H. azteca, while the length and number of antennal segments are not informative.