Growth Conditions Research Articles

Tracing residual patterns and microbial communities of pharmaceuticals and personal care products from 17 urban landfills leachate in China

Landfill leachate contributes significantly to the presence of pharmaceuticals and personal care products (PPCPs) in the environment, and is a crucial source of contamination. To examine the occurrence of PPCPs and microbial communities, this study comprehensively investigated the concentrations of PPCPs and the abundance of microorganisms in the leachate from 17 municipal landfills across China. Generally, Lidocaine, Linear alkylbenzene sulfonate-C11, and Triclocarban, which are closely associated with human activities, exhibited a detection frequency of 100 % in the leachate. Driven by consumer demand, analgesic and antipyretic drugs have emerged as the most prominent PPCPs in leachate (accounting for 39.9 %). Notably, the Ibuprofen peaked at 56.3 μg/L. Regarding spatial distribution, the contamination of PPCPs in leachates from the eastern regions of China was significantly higher than that in other regions, owing to the level of economic development and demographic factors. Furthermore, the 16S rRNA results revealed significant differences in microbial communities among the leachates from different areas. Although the impact of PPCPs on microbial communities may not be as significant as that of environmental factors, most positive correlations between PPCPs and microorganisms indicate their potential role in providing nutrients and creating favorable conditions for microbial growth. Overall, this research offers new perspectives on the residual features of PPCPs and the microbial community structure in leachates from various regions in China.

Factors Affecting Purchasing Behavior in Buying of Passenger Cars

This study is about the consumer behavior in buying of passenger cars in Nepal. It aimed to identify the factors affecting the consumer behavior in car purchase. It used primary data, which came from a structured questionnaire on the six-point Likert scale that was sent to Nepalese car owners. Kathmandu was chosen as the sample site for our convenience to reach. Primary data was collected through the structured questionnaire. 411 car users were the sample size. SPSS software was used to prepare and look at the data. Through the path analysis, the effect of attributes, price, appearance, self-congruity, and brand personality on consumer buying behavior was examined using the structural equation modeling. The study found that there is significant positive impact of product attributes (β=.175, p=.012) on consumer behavior. It is also discovered that there is a significant positive effect of brand personality (β=.152, p=.032) and self-congruity (β=.619, p=.000) on consumer choice behavior but it was found that the product price (β=.073, p=.271) and product appearance (β=.084, p=.180) have no significant influence on consumer buying behavior towards passenger cars in Nepalese market. The study's results show how future researchers and business people can look at the new conditions for market growth.

Mixed planting of subtropical Chinese fir in South China improves microbial carbon source metabolism and functional diversity through the accumulation of nutrients from soil aggregates.

Soil microbial functional traits are key indicators of soil microbial ecological traits; however, how mixing patterns of Chinese fir and broadleaved trees drive soil microbial functional trait variation at the aggregate scale and how soil microbial functional traits are linked to soil fertility factors have largely not been determined. In this study, soil from the 0-20 cm depths in three Chinese fir plantations was collected, and the soil samples were separated into >2 mm (large macro-aggregate), 0.25-2 mm (macro-aggregate) and <0.25 mm (micro-aggregate) by complying with an optimal moisture sieving procedure. The metabolic activities, functional diversity and different carbon sources utilization characteristics of the soil microorganisms were determined by the Biolog Eco microplate method. In all Chinese fir plantations, micro-aggregates (<0.25 mm) consistently exhibited the highest levels of microbial metabolic activity, a more uniform carbon source utilisation capacity, and the highest microbial diversity. Micro-aggregates also showed elevated levels of soil organic carbon (OC), total nitrogen (TN), total phosphorus (TP), and higher ratios of C/N and C/P compared to large macro-aggregates and macro-aggregates, indicating that micro-aggregates contain more resources available to soil microorganisms. Soil OC, TN, and TP content were enhanced by integration with Michelia macclurei, suggesting that this combination promotes relatively favourable soil conditions for microbial growth and multiplication. This, in turn, promotes microbial metabolic activity. Furthermore, redundancy and correlation analyses showed that soil OC, TN, and TP were identified as principal determinants of soil microbial functional properties in Chinese fir plantations. In summary, mixed cultivation and aggregate size influenced microbial functional properties via soil nutrient alterations. Consequently, adopting a mixed cultivation approach of Chinese fir and broadleaved trees is advocated in the subtropical regions of Guangxi. Employing a diversity of tree species, including M. macclurei, is recommended for optimal soil quality preservation.

Proximity driven plastid-nucleus relationships are facilitated by tandem plastid-ER dynamics.

Peri-nuclear clustering (PNC) of chloroplasts has largely been described in senescent and pathogen- or ROS- stressed cells. Stromules, tubular plastid extensions are also observed under similar conditions. Coincident observations of PNC and stromules associate the two phenomena in facilitating retrograde signaling between chloroplasts and the nucleus. However, PNC incidence in non-stressed cells under normal growth and developmental conditions, when stromules are usually not observed, remains unclear. Using transgenic Arabidopsis expressing different organelle-targeted fluorescent proteins we show that PNC is a dynamic subcellular phenomenon that continues in the absence of light and is not dependent on stromule formation. PNC is facilitated by tandem plastid-ER dynamics created through membrane contact sites between the two organelles. While PNC increases upon ER-membrane expansion, some plastids may remain in the peri-nuclear region due to their localization in ER-lined nuclear indentions. Moreover, some PNC plastids may sporadically extend stromules into ER-lined nuclear grooves. Our findings strongly suggest that PNC is not an exclusive response to stress caused by pathogens, high light or exogenous-H2O2 treatment and does not require stromule formation. However, morphological and behavioural alterations in ER and concomitant changes in tandem, plastid-ER dynamics play a major role in facilitating the phenomenon.

COMPARATIVE ANALYSIS OF SOME SOYBEAN GENOTYPES BASED ON BIOMETRIC PARAMETERS

The study made a comparative analysis regarding the behavior of some soybean genotypes in non-irrigated crop system. Experiments were carried out within ARDS Lovrin, on a chernozem type soil with medium fertility. The following genotypes were cultivated: 'Calma', 'Caro', 'Isa', 'Karavukovo', 'Perla', and 'Ziana'. Sowing was done at the optimal time, at a distance of 70 cm between rows, and the crop technology ensured favorable conditions for plant growth. At physiological maturity, plant samples were taken and determinations were made regarding: plant density (PD, plants/m2), plant weight (PW, kg/m2), soybean pod weight (SpW, kg/m2), soybean grain weight (SgW, kg/m2), soybean pods shells weight (SpsW, kg/m2). Based on the recorded values, the yield of soybeans in relation to pods (Y, %) was calculated. PW/SpW, PW/SgW, and PsW/SgW ratios were also calculated. Very strong, positive correlation was recorded between SgW and SpW (r = 0.998), between Y (%) and SpW (r = 0.923), and between Y and SgW (r = 0.944). According to PCA, PC1 explained 74.369% of variance, and PC2 explained 14.769% of variance. The Cluster Analysis generated the dendrogram of soybean genotypes based on similarity (Coph.corr = 0.972), and a high level of similarity was recorded between 'Calma' and 'Isa' genotypes (SDI = 1.6926). In relation to the average value of the experiment, the 'Perla' genotype stood out for the PW parameter, the 'Ziana' genotype for the SpW parameter, the 'Ziana' genotype for the SgW parameter, and the 'Perla' genotype for yield (Y, %).

Study on the Identification, Biological Characteristics, and Fungicide Sensitivity of the Causal Agent of Strawberry Red Core Root Rot

Strawberry red core root rot disease affects the growth and yield of strawberry (Fragaria ananassa Duch), which leads to economic losses in China. The study employed a tissue separation method to isolate and identify the causal agent responsible for strawberry red core root rot. This was achieved by the observation of its morphological characteristics, sequencing analyses, and pathogenicity tests. The sensitivity of five chemical fungicides against the two species of Fusarium was determined using the mycelial growth rate method, and the biological characteristics of the two species were examined. The pathogens were identified as Fusarium solani and Fusarium oxysporum. The optimal conditions for the mycelial growth of F. solani and F. oxysporum were determined to be potato sucrose agar at 25 °C and pH 6, and potato dextrose agar at 30 °C and pH 8, respectively, with a 24:24 light cycle. The most suitable carbon and nitrogen sources for the mycelial growth of F. solani were sucrose and sodium nitrate (NaNO3), while for F. oxysporum, they were glucose and peptone. A fungicide sensitivity test indicated that Prochloraz had a good inhibitory effect on the growth of F. solani and F. oxysporum with EC50 values of 0.088 mg L−1 and 0.162 mg. The growth inhibition effect of Azoxystrobin to F. solani and Carbendazim to F. oxysporum was not obvious. This study provides a theoretical basis for further research on strawberry red core root disease and its prevention.

PRODUCTION AND SOME QUALITY INDICES VARIATION IN CORN - CASE STUDY IN FARM CONDITIONS

The study comparatively analyzed the production results and the values ​​of some quality indices for two corn hybrids, in the specific crop conditions of the Western Plain of Romania. Corn crops was carried out in the area of ​​Grabaț locality, Timis County, Romania. Corn hybrids P9889 and DKC5092 were cultivated, in a non-irrigated system, between 2021 and 2023. Adequate plant growth conditions were ensured through crop technology. In the case of the P9889 hybrid, the productions were 8500 kg/ha (2021), 5350 kg/ha (2022), and 11000 kg/ha (2023). In the case of the DKC5092 hybrid, the productions were 7900 kg/ha (2021), 5800 kg/ha (2022) and 10800 kg/ha (2023). Based on mean grains samples, the crude protein content (CP) showed values ​​between 8.5% (year 2021) and 10.05% (year 2023); the starch content (ST) presented values ​​between 54.09% (year 2021) and 59.04% (year 2023); the crude cellulose content (crude fibers, CF) presented values ​​between 1.99% (year 2021) and 2.25% (year 2023); the proportion of broken grains (BG) showed values ​​between 0.98 (year 2023) and 1.3% (year 2022), with an mean value BG = 1.10%. A very strong positive correlation was recorded between CP and M (r = 0.955), between ST and M (r = 0.900), and between ST and CP (r = 0.989). Very strong negative correlation was recorded between Y and BG (r = - 0.926). A strong, positive correlation was recorded between CF and Y (r = 0.834), and between CF and M (r = 0.865). According to PCA, PC1 explained 60.307% of variance, and PC2 explained 39.693% of variance. The decrease in production in 2022 (extremely dry year), compared to the mean value, was DY = -2933.33 kg/ha for the P9889 hybrid, respectively DY = -2366.67 kg/ha for the DKC5092 hybrid. From the analysis of the obtained values, the hybrid P9889 recorded a greater decrease in production (difference of 566.66 kg/ha) compared to the hybrid DKC5092, under the conditions of 2022, specific to the study conditions.

Effect of CUP1 copy number and pH on copper resistance of Saccharomyces cerevisiae enological strains

The widespread use of copper-based pesticides in winemaking can affect wine fermentation. Therefore, it is crucial to assess the resistance levels of Saccharomyces cerevisiae wine strains in enological growth conditions. In the context of winemaking, grape juice is a complex environment capable of chelating copper and is characterized by a distinctly acidic pH. In this work, the effects of copper concentration on the growth of 10 S. cerevisiae strains, isolated from an enological environment, and one commercial starter were tested in YNB minimal medium and synthetic must, mimicking enological conditions.In minimal medium, resistance to copper varied among yeasts (50–600 μM), revealing the presence of three resistance levels (high, intermediate, and low). Representative strains of the three groups were tested at a pH range from 5.2 to 3.0 at the copper concentration that showed a 20–25 % growth reduction. At pH range 5.2–4.5, a growth reduction was observed, while, conversely, a strain-specific recovery was observed at pH range 3.2–3.0.In synthetic must, the strains showed higher copper resistance levels than in minimal medium (50–4000 μM). In both synthetic must and minimal medium, a significant logarithmic correlation was found between copper resistance and CUP1 gene copy number. The copy number tended to better explain resistance in minimal medium compared to synthetic must. The results shed light on the role of CUP1 copy number within an enological environment.

Bdellovibrio’s prey-independent lifestyle is fueled by amino acids as a carbon source

Identifying the nutritional requirements and growth conditions of microorganisms is crucial for determining their applicability in industry and understanding their role in clinical ecology. Predatory bacteria such as Bdellovibrio bacteriovorus have emerged as promising tools for combating infections by human bacterial pathogens due to their natural killing features. Bdellovibrio’s lifecycle occurs inside prey cells, using the cytoplasm as a source of nutrients and energy. However, this lifecycle supposes a challenge when determining the specific uptake of metabolites from the prey to complete the growth inside cells, a process that has not been completely elucidated. Here, following a model-based approach, we illuminate the ability of B. bacteriovorus to replicate DNA, increase biomass, and generate adenosine triphosphate (ATP) in an amino acid-based rich media in the absence of prey, keeping intact its predatory capacity. In this culture, we determined the main carbon sources used and their preference, being glutamate, serine, aspartate, isoleucine, and threonine. This study offers new insights into the role of predatory bacteria in natural environments and establishes the basis for developing new Bdellovibrio applications using appropriate metabolic and physiological methodologies.Key points• Amino acids support axenic lifestyle of Bdellovibrio bacteriovorus.• B. bacteriovorus preserves its predatory ability when growing in the absence of prey.

Mixotrophic growth of a ubiquitous marine diatom.

Diatoms are major players in the global carbon cycle, and their metabolism is affected by ocean conditions. Understanding the impact of changing inorganic nutrients in the oceans on diatoms is crucial, given the changes in global carbon dioxide levels. Here, we present a genome-scale metabolic model (iMK1961) for Cylindrotheca closterium, an in silico resource to understand uncharacterized metabolic functions in this ubiquitous diatom. iMK1961 represents the largest diatom metabolic model to date, comprising 1961 open reading frames and 6718 reactions. With iMK1961, we identified the metabolic response signature to cope with drastic changes in growth conditions. Comparing model predictions with Tara Oceans transcriptomics data unraveled C. closterium's metabolism in situ. Unexpectedly, the diatom only grows photoautotrophically in 21% of the sunlit ocean samples, while the majority of the samples indicate a mixotrophic (71%) or, in some cases, even a heterotrophic (8%) lifestyle in the light. Our findings highlight C. closterium's metabolic flexibility and its potential role in global carbon cycling.

Evaluating hybrid nuclear-thermal power systems for reduced carbon footprint: A comparative analysis

The article provides an estimated substantiation of the concept of expanding the fuel and energy base and reducing the volume of greenhouse gas emissions with the joint use of organic and nuclear fuel in the structure of hybrid nuclear-thermal power plants. It is shown that the technological scheme (the production of saturated steam in a nuclear steam-producing plant - NPPU, and then overheating to the maximum achieved parameters in the thermal power industry due to organic fuel) leads to a decrease in the specific consumption of gas fuel for the production of electrical energy by 25–30 %, emissions of combustion products by 2.5 times (compared to thermal power plants), consumption of industrial water (compared to nuclear power plants) - by 1.5 times. It is indicated that it is possible to expand the fuel base of modern nuclear energy with thermal neutron reactors through the use of technologies mastered (breeder reactors) and promising (hybrid thermonuclear reactors). The fundamental advantage of the considered complex - JPPP-TPP - its feasibility in a short period of time with a significant reduction in the carbon footprint per unit of energy produced, which is an important condition for the sustainable growth of energy production while maintaining the ecological balance in the geosphere.

Shifting Mycobacterial Serine Hydrolase Activity Visualized Using Multi-Layer In-Gel Activity Assays.

The ability of Mycobacterium tuberculosis to derive lipids from the host, store them intracellularly, and then break them down into energy requires a battery of serine hydrolases. Serine hydrolases are a large, diverse enzyme family with functional roles in dormant, active, and reactivating mycobacterial cultures. To rapidly measure substrate-dependent shifts in mycobacterial serine hydrolase activity, we combined a robust mycobacterial growth system of nitrogen limitation and variable carbon availability with nimble in-gel fluorogenic enzyme measurements. Using this methodology, we rapidly analyzed a range of ester substrates, identified multiple hydrolases concurrently, observed functional enzyme shifts, and measured global substrate preferences. Within every growth condition, mycobacterial hydrolases displayed the full, dynamic range of upregulated, downregulated, and constitutively active hydrolases independent of the ester substrate. Increasing the alkyl chain length of the ester substrate also allowed visualization of distinct hydrolase activity likely corresponding with lipases most responsible for lipid breakdown. The most robust expression of hydrolase activity was observed under the highest stress growth conditions, reflecting the induction of multiple metabolic pathways scavenging for energy to survive under this high stress. The unique hydrolases present under these high-stress conditions could represent novel drug targets for combination treatment with current front-line therapeutics. Combining diverse fluorogenic esters with in-gel activity measurements provides a rapid, customizable, and sensitive detection method for mycobacterial serine hydrolase activity.

Impact of mineral and non-mineral sources of iron and sulfur on the metalloproteome of Methanosarcina barkeri.

Methanogens often inhabit sulfidic environments that favor the precipitation of transition metals such as iron (Fe) as metal sulfides, including mackinawite (FeS) and pyrite (FeS2). These metal sulfides have historically been considered biologically unavailable. Nonetheless, methanogens are commonly cultivated with sulfide (HS-) as a sulfur source, a condition that would be expected to favor metal precipitation and thus limit metal availability. Recent studies have shown that methanogens can access Fe and sulfur (S) from FeS and FeS2 to sustain growth. As such, medium supplied with FeS2 should lead to higher availability of transition metals when compared to medium supplied with HS-. Here, we examined how transition metal availability under sulfidic (i.e., cells provided with HS- as sole S source) versus non-sulfidic (cells provided with FeS2 as sole S source) conditions impact the metalloproteome of Methanosarcina barkeri Fusaro. To achieve this, we employed size exclusion chromatography coupled with inductively coupled plasma mass spectrometry and shotgun proteomics. Significant changes were observed in the composition and abundance of iron, cobalt, nickel, zinc, and molybdenum proteins. Among the differences were alterations in the stoichiometry and abundance of multisubunit protein complexes involved in methanogenesis and electron transport chains. Our data suggest that M. barkeri utilizes the minimal iron-sulfur cluster complex and canonical cysteine biosynthesis proteins when grown on FeS2 but uses the canonical Suf pathway in conjunction with the tRNA-Sep cysteine pathway for iron-sulfur cluster and cysteine biosynthesis under sulfidic growth conditions.IMPORTANCEProteins that catalyze biochemical reactions often require transition metals that can have a high affinity for sulfur, another required element for life. Thus, the availability of metals and sulfur are intertwined and can have large impacts on an organismismal biochemistry. Methanogens often occupy anoxic, sulfide-rich (euxinic) environments that favor the precipitation of transition metals as metal sulfides, thereby creating presumed metal limitation. Recently, several methanogens have been shown to acquire iron and sulfur from pyrite, an abundant iron-sulfide mineral that was traditionally considered to be unavailable to biology. The work presented here provides new insights into the distribution of metalloproteins, and metal uptake of Methanosarcina barkeri Fusaro grown under euxinic or pyritic growth conditions. Thorough characterizations of this methanogen under different metal and sulfur conditions increase our understanding of the influence of metal availability on methanogens, and presumably other anaerobes, that inhabit euxinic environments.

On Liouville type results for the stationary MHD in R3

This paper is concerned with the Liouville type theorems for the steady incompressible magnetohydrodynamics (MHD) equations. We establish that the solution to the steady MHD equations is identically zero under the integrability assumptions on (v, b). We show that, in particular, a combination of a strong integrability condition on the velocity of a fluid and a weak integrability condition on the magnetic field gives a sufficient condition on the Liouville type theorems. Furthermore, we show that the combination of the growth condition of the potential for the fluid velocity and the integrability condition for the magnetic field leads to the triviality of the solution.

Optimization of bacterial consortia for enhanced cadmium removal from contaminated environments: a case study near the Cochin Backwater System, Kerala, India

Heavy metal contamination is a major environmental and ecological threat worldwide, posing significant challenges. Excessive accumulation of heavy metal like cadmium in the environment poses significant risks to both the environment and human health, particularly in regions with industrial activities and insufficient waste management practices. In this study, we focused on optimizing bacterial consortia composed of Aeromonas hydrophila and Psychrobacter nivimaris for efficient removal of cadmium from contaminated environments, with specific emphasis on areas near the Cochin backwater system in Kerala, India. Sampling conducted at Sreebhoothapuram and Eloor Ferry Kadavu stations near Fertilizers and Chemicals Travancore (FACT) revealed these sites as having significant cadmium accumulation. Bacterial strains isolated from these stations exhibited notable resistance to cadmium, with levels reaching up to 40 mg/l and these strains maintained similar growth conditions, making them good candidates for constructing a bacterial consortium. The Cd-resistant bacteria were characterized and identified as Aeromonas hydrophila and Psychrobacter nivimaris. Through a synergetic approach, a consortium comprising two bacterial strains from different combinations obtained from these stations demonstrated promising cadmium resistance, reaching up to 60 mg/l. Mixture design optimization facilitated the determination of an optimal ratio (Aeromonas hydrophila: Psychrobacter nivimaris) = (0.329:0.671) for maximum removal efficiency. The scanning electron microscopy (SEM) analysis of both individuals and the consortium revealed morphological changes, such as modifications in the cell wall, shape, and size of the bacteria, that occur during the absorption of Cd (II). The efficiency of the optimized consortium was validated through Atomic Absorption Spectroscopy, achieving an impressive removal percentage of 96.5% for a real wastewater sample with a Relative Standard Deviation (RSD) less than 10%. This study underscores the potential of tailored bacterial consortia as effective bioremediation agents for Cd-contaminated environments, particularly in regions with elevated cadmium levels like the Cochin backwater system in Kerala.

FetalAI: A deep learning web-based application for predicting birthweight from prenatal ultrasound measurements

FetalAI is a web-based application that utilizes a longitudinal learning procedure that integrates data augmentation and deep learning as back-end, with a purpose of predicting an newborn’s projected birthweights and the associated risks of excessive fetal growth conditions, including large-for-gestational-age (LGA) and macrosomia. This article provides an end-to-end overview of FetalAI’s development process, which includes data sourcing and preprocessing, back-end model design and training, application output interpretation, and user interactions. We begin by describing the original training data sources and their mathematical structures. We then outline the data engineering pipeline that acquires and pre-processes user input. After data sourcing and pre-processing, we provide details on the back-end model, which applies mixed-effects models for data augmentation and pre-trained recurrent neural networks (RNNs) to forecast birthweight sequences. After back-end, we discuss the front-end development of FetalAI, with an emphasis on creating the graphical user interface (GUI) using Streamlit and the application’s ability to handle corner cases and anomalous inputs. Our article concludes by highlighting the key functionalities and potential use cases of FetalAI, as well as outlining future directions for research and development in this domain. FetalAI represents a significant step forward in the application of deep learning techniques to improve prenatal care and support clinical decision-making.

Effect of Mixed Cultures on Microbiological Development in Berliner Weisse Beer

Sour beers play an important role in the brewing market, and their production has been growing exponentially. In light of this, six microorganisms directly related to this class of beer were studied, and the fermentation behavior of six strains used in the past for traditional commercial Berliner Weisse beer production was monitored. The microorganisms used were Lactobacillus brevis, Lactobacillus parabrevis, Brettanomyces bruxellensis, and Brettanomyces anomalus and two strains of Saccharomyces cerevisiae. The six microorganisms were selected in a previous work, and a comparison between single and mixed fermentations was carried out via daily measurements of the fermentation parameters like pH, extract, and cell count during 22 days. The ability to isolate a specific microorganism from a mixed culture was investigated using three commonly used nutrient media and aerobic/anaerobic growth conditions. Both Lactobacillus and Brettanomyces could be isolated; however, the conditions imposed were not sufficient in order to isolate Saccharomyces. Fermentations carried out with LAB and Brettanomyces showed a decrease in Lactobacillus growth if compared to pure fermentations, but no influence on the growth of Brettanomyces could be perceived. In general, fermentations carried out in the presence of Saccharomyces were dominated by this yeast. Its quick growth seems to be responsible for the high end pH values observed as well as the decrease in cell growth for both LAB and Brettanomyces. A decrease in the cell viability of Saccharomyces was followed by an increased growth of the other microorganisms involved, possibly meaning that the molecules released through apoptosis are used by both LAB and Brettanomyces as a valuable nutrient source. The volatile compound concentrations of the first group were higher in fermentations with Saccharomyces, whereas esters’ concentration was higher in fermentations carried out only with Brettanomyces and Lactobacillus. Furthermore, understanding how these microorganisms interact during the fermentation process can help brewers better control production and ensure the consistency in the quality of the final product. The end pH values and acidity reached levels acceptable for Berliner Weisse beer. This innovative approach certainly contributes to the evolution and refinement of the art of brewing.

MSMEG_5850, a global TetR family member supports Mycobacterium smegmatis to survive environmental stress.

A Mycobacterium smegmatis transcriptional regulator, MSMEG_5850, and its ortholog in M. tuberculosis, rv0775 were annotated as putative TetR Family Transcriptional Regulators. Our previous study revealed MSMEG_5850 is involved in global transcriptional regulation in M. smegmatis and the presence of gene product supported the survival of bacteria during nutritional starvation. Phylogenetic analysis showed that MSMEG_5850 diverged early in comparison to its counterparts in virulent strains. Therefore, the expression pattern of MSMEG_5850 and its counterpart, rv0775, was compared during various in-vitro growth and stress conditions. Expression of MSMEG_5850 was induced under different environmental stresses while no change in expression was observed under mid-exponential and stationary phases. No expression of rv0775 was observed under any stress condition tested, while the gene was expressed during the mid-exponential phase that declined in the stationary phase. The effect of MSMEG_5850 on the survival of M. smegmatis under stress conditions and growth pattern was studied using wild type, knockout, and supplemented strain. Deletion of MSMEG_5850 resulted in altered colony morphology, biofilm/pellicle formation, and growth pattern of M. smegmatis. The survival rate of wild-type MSMEG_5850 was higher in comparison to knockout under different environmental stresses. Overall, this study suggested the role of MSMEG_5850 in the growth and adaptation/survival of M. smegmatis under stress conditions.

Physiological, transcriptomic and metabolomic insights of three extremophyte woody species living in the multi-stress environment of the Atacama Desert.

In contrast to Neltuma species, S. tamarugo exhibited higher stress tolerance, maintaining photosynthetic performance through enhanced gene expression and metabolites. Differentially accumulated metabolites include chlorophyll and carotenoids and accumulation of non-nitrogen osmoprotectants. Plant species have developed different adaptive strategies to live under extreme environmental conditions. Hypothetically, extremophyte species present a unique configuration of physiological functions that prioritize stress-tolerance mechanisms while carefully managing resource allocation for photosynthesis. This could be particularly challenging under a multi-stress environment, where the synthesis of multiple and sequential molecular mechanisms is induced. We explored this hypothesis in three phylogenetically related woody species co-occurring in the Atacama Desert, Strombocarpa tamarugo, Neltuma alba, and Neltuma chilensis, by analyzing their leaf dehydration and freezing tolerance and by characterizing their photosynthetic performance under natural growth conditions. Besides, the transcriptomic profiling, biochemical analyses of leaf pigments, and metabolite analysis by untargeted metabolomics were conducted to study gene expression and metabolomic landscape within this challenging multi-stress environment. S. tamarugo showed a higher photosynthetic capacity and leaf stress tolerance than the other species. In this species, a multifactorial response was observed, which involves high photochemical activity associated with a higher content of chlorophylls and β-carotene. The oxidative damage of the photosynthetic apparatus is probably attenuated by the synthesis of complex antioxidant molecules in the three species, but S. tamarugo showed the highest antioxidant capacity. Comparative transcriptomic and metabolomic analyses among the species showed the differential expression of genes involved in the biosynthetic pathways of key stress-related metabolites. Moreover, the synthesis of non-nitrogen osmoprotectant molecules, such as ciceritol and mannitol in S. tamarugo, would allow the nitrogen allocation to support its high photosynthetic capacity without compromising leaf dehydration tolerance and freezing stress avoidance.

Analysis of Bacterial DNA from Bioreactor Effluent Samples for Hydrogen Production by Dark Fermentation

Hydrogen (H2) production from biomass using bacteria is a cost-effective approach. The bacterial DNA from effluent samples were extracted, amplified and analysed, and taxonomic trees of all the species present were obtained. HRTs and synthetic matrix influenced bacterial growth. Clostridium butyricum was prominent in the samples indicating its versatile growth conditions.