Salinity-alkalinity gradients impose strong environmental filtering on soil microbial communities, yet the respective roles of generalist and specialist taxa in community assembly and stability remain insufficiently understood in wetland ecosystems. Here, bacterial and fungal communities were investigated across low, moderate, and high saline-alkaline zones in the Luyang Lake wetland, China. Amplicon sequencing was integrated with niche breadth analysis, community assembly inference, co-occurrence network analysis, cohesion metrics, and partial least squares path modeling to assess how generalists and specialists responded to environmental variation and contributed to microbial stability. Bacteria contained a larger generalist pool, whereas fungi were relatively enriched in specialists. Generalists were positively associated with nutrient availability and negatively associated with saline-alkaline stress, while bacterial specialists showed the opposite trend. Niche breadth decreased with increasing salinity-alkalinity, especially in bacteria, and this narrowing was accompanied by stronger deterministic assembly, mainly homogeneous selection. Network analysis further suggested that generalists contributed more to overall community connectivity, whereas specialists became more important for network organization under stronger saline-alkaline stress. Path modeling indicated that bacterial and fungal community stability was associated with distinct response pathways. Overall, salinity-alkalinity reorganized microbial communities by reducing niche breadth, strengthening deterministic assembly, and shifting the relative contributions of generalists and specialists to community stability. These findings improve our understanding of how niche strategy mediates microbial assembly and stability in saline-alkaline wetland soils.
Pneumocandin B0 is a secondary metabolite that acts as a precursor for caspofungin acetate, an antifungal drug. This study focuses on the development of an upstream process for pneumocandin B0 production through fermentation condition optimization and mutagenesis. A response surface methodology (RSM)-based central composite design (CCD) was employed to increase the production of pneumocandin B0 in Glarea lozoyensis ATCC 20868. The four independent variables (mannitol, fructose, soybean meal, and pH) were chosen at three different levels to obtain the optimum conditions for pneumocandin B0 production. The optimized process conditions using RSM-CCD resulted in 29.4 mg/L pneumocandin (11.76-fold increase compared with that of wild-type). To improve pneumocandin B0 production, mutagenesis (physical/chemical) was also performed using gamma-irradiation and methyl methane sulfonate (MMS). The best-performing MMS-induced mutant strain in optimized medium resulted in increased pneumocandin B0, i.e., 74.17 mg/L (29-fold increase compared with that of wild-type), at the 2-L shake flask level. Additionally, morphological analysis using scanning electron microscopy revealed significant structural changes in the mutant strains, including altered hyphal and mycelial morphology. These findings suggest that mutagenesis not only enhances production but also modifies cellular physiology. In conclusion, this study presents an integrated strategy that combines media optimization and mutagenesis to significantly increase pneumocandin B₀ production.
To evaluate the microbiological quality of a hospital's treated water distribution system, characterize opportunistic bacterial isolates and their antimicrobial susceptibility profiles, investigate the genetic relatedness between environmental and clinical isolates from a One Health perspective. Prospective observational study. A total of 352 water samples were collected over six months from strategic locations within a public teaching hospital. Samples were analyzed for total coliforms, Escherichia coli, heterotrophic bacteria (HB), bacterial isolation and identification, antimicrobial susceptibility testing, and ERIC-PCR genotyping was applied to Pseudomonas aeruginosa isolates to analyse their similarity with clinical isolates. Statistical analysis used the chi-square test of independence (χ2). Despite legal compliance for coliforms, elevated HB counts were found in 17
The presence of Listeria monocytogenes in food represents a major challenge to food safety, especially in ready-to-eat products stored under refrigeration. This risk is associated with the ability of the pathogen to survive and multiply during prolonged refrigerated storage, making these foods potential sources of infection and a relevant public health concern. In this context, the aim of this study was to investigate the presence of Listeria monocytogenes in chilled processed meat products sold in bulk in the Metropolitan Region of Recife, PE, Brazil, as well as to evaluate the antimicrobial susceptibility profile of the isolates. A total of 48 samples of sausages and ham from different brands were analyzed, obtained from public markets and supermarkets in the region. Detection of Listeria spp. was performed using conventional methods recommended by the Ministry of Agriculture and Livestock, and antimicrobial susceptibility was assessed by the disk diffusion method. Of the analyzed products, 27/48 (56.25
One of the main strategies Gram-negative bacteria employ to lower internal antibiotic concentrations is efflux. By identifying and eliminating a variety of harmful substances, including antibiotics, these active transport systems help bacteria become less susceptible to drugs and develop new resistance mechanisms. Efflux pumps are involved in bacterial stress response, pathogenicity, biofilm formation, and host physiology alteration in addition to offering an escape from antibacterial chemicals. This research is designed to study the prevalence of efflux pump genes and the measure expression of )AcrAB, MarA, MdtK OmpK35 and OmpK36 genes before and after treatment with combination of Ciprofloxacin (CIP) and Amikacin (AMC) antibiotic CIP of Klebsiella pneumoniae isolated from hospitalized patients in Iraq hospitals. During a six-month cross-sectional survey (January–June 2025), twenty K. pneumoniae strains were collected from patients admitted to several teaching hospitals. Their antimicrobial sensitivity was determined by applying the agar-based disk diffusion assay. The ethidium bromide (EtBr) agar cartwheel method can be used to phenotypically detect the activity of efflux pumps in K. pneumoniae isolates. The PCR method was used to determine the frequency of genes encoding AcrAB, marA, mdtK, ompK35, and ompK36 in K. pneumoniae, and the Real-time PCR method was used to determine the expression of the efflux pump gene exposed to ciprofloxacin and amoxicillin. The findings indicate that 90
Lacticaseibacillus rhamnosus is an important strain for the biotransformation of natural products, and its crude extract exhibits biotransformation effect on glycosidic compounds such as baicalin. To further explore the potential of this strain, particularly given its previously demonstrated high-efficiency β-glucuronidase activity for baicalin conversion, whole-genome sequencing and functional annotation of Lacticaseibacillus rhamnosus HP-B1083 were performed in this study, and its acid tolerance, bile salt tolerance, short-term heat resistance and antibacterial activity were evaluated. The results showed that the strain possessed a circular chromosome with a full length of 3,090,505 bp and a GC content of 46.69
The common bean is of great importance for human nutrition worldwide as its grain is a cheap source of protein, but it has a high-cost production system due to the use of synthetic inputs such as nitrogen fertilizers and pest and disease control products. An alternative to promote the sustainability of the production system and increase crop productivity is the use of co-inoculation of plant growth-promoting rhizobacteria (PGPR) to reduce and/or replace the use of nitrogen fertilizers and pest and disease control products. Since 2010, Brazil has stood out on the international stage with research focused on the application of rhizobia combined with PGPR in bean crops. Currently, the use of microorganisms that effectively promote plant growth through different mechanisms of action is already a consolidated reality in Brazil, with experimental results proven by years of research. Despite these advances, there are still challenges to overcome to maximize the potential of co-inoculation in bean crops. These include the need to develop more efficient formulations containing elite microbial strains and optimized microbial consortia, as well as the search for inoculation methods that optimize root colonization by the bacteria and maximize their beneficial effects on the plant. In this review, we discuss the history of common-bean production and the types and doses of inoculants marketed, as well as the challenges for the efficiency of co-inoculation and for the development of inoculants of rhizobial consortia with PGPRs for the common-bean cultivation.
Urban wastewater systems represent important interfaces between human activity and the environmental occurrence of antimicrobial resistance (AMR) markers. We assessed the temporal dynamics of intI1, ermB, and the 16 S rRNA gene by quantitative PCR across three wastewater systems (EPC, CJC, and JW) in Fortaleza, Brazil, from November 2021 to November 2023. Bacterial communities were additionally characterized by 16 S rRNA gene metabarcoding in 18 samples collected in December 2021 and January 2022. A synchronized decline in 16 S rRNA gene and intI1 concentrations beginning in late 2022 was observed across all three wastewater systems, suggesting a shift toward lower microbial abundance. The ermB gene showed higher and more variable concentrations during part of the pandemic period, followed by convergence toward lower levels; however, the absence of antimicrobial-consumption data precluded attribution of this pattern to changes in macrolide selective pressure. Normalized antimicrobial resistance marker abundances were comparatively stable at EPC and JW but more variable at CJC. EPC exhibited the highest ASV richness, whereas CJC and JW showed greater diversity according to Shannon and inverse Simpson indices. Beta-diversity analyses identified wastewater system as the principal factor associated with bacterial community structure, while the effect of sampling period was smaller and metric-dependent. Neither ermB nor intI1 was individually associated with community composition, although intI1 showed a limited effect after adjustment for wastewater system in one model. Physicochemical parameters were not significantly associated with normalized marker abundances in the exploratory paired analysis. Arcobacter, Acinetobacter, and other potentially relevant genera were detected, but no direct associations between these taxa and the monitored AMR markers could be established. These findings highlight the value of integrating longitudinal qPCR, microbiome profiling, and environmental characterization to improve the interpretation of targeted AMR markers in One Health wastewater surveillance.
This study presents novel insights into the proteolytic activity of lactic acid bacteria (LAB) and their combinations with propionic acid bacteria (PAB), addressing the current gap in understanding the mechanisms of milk protein hydrolysis during dairy fermentation. The research involved a comprehensive analysis of 12 strains of Lactococcus spp. and 4 strains of Streptococcus spp., along with their combinations with PAB. Using SDS-PAGE electrophoresis, spectrophotometry, and high-performance liquid chromatography, the study investigated the proteolytic characteristics of these microorganisms during skim milk fermentation. Key findings revealed distinct patterns of protein hydrolysis. Preferential cleavage of β-casein was shown for the L. lactis 782 M-A proteolytic system, whereas S. thermophilus 1095 ST-AV, Propionibacterium sp. 2388 MYO-К and L. casei 1188 ML-OF hydrolysed α- and β-casein. However, whey proteins were not found to be proteolysed. Notably, the combination of PAB with lactococci demonstrated enhanced casein hydrolysis compared to individual strains. The research identified varying levels of proteolytic activity among different strains. The maximum proteolytic activity recorded was 2.54–3.12 mg/ml for Propionibacterium sp. 2388 MYO-K. The most significant finding was the complete hydrolysis of the casein fraction observed when milk was fermented by PAB in combination with lactococci or the L. lactis 782 M-A and S. thermophilus 1095 ST-AV combination. The results obtained can be applied to optimize fermentation processes and develop functional dairy products with tailored protein-peptide profiles. The results contribute to a better understanding of how to select appropriate bacterial strains for specific dairy fermentation processes based on their proteolytic characteristics.
Continental slopes, particularly the pockmark and salt diapir regions of the Santos Basin, represent extreme environments characterized by high hydrostatic pressure, low temperatures, elevated salinity, and limited organic matter, fostering unique bacterial communities. This study aimed to elucidate the metabolic strategies enabling survival in these conditions by exploring the genome of a Chromohalobacter israelensis strain isolated from such sediments, utilizing long-read sequencing. The genome, assembled into a single 3.8 Mb contig with 98.9
Brucellosis is one of the most severe Class B infectious diseases prevalent in the agricultural and pastoral areas of northern China. Current attenuated live vaccines (e.g., M5, S19) have defects such as residual virulence, causing abortion in pregnant animals, and the inability to differentiate between natural infection and vaccination (DIVA). Relying on the ABSL-3 laboratory of the Inner Mongolia Center for Disease Control and Prevention, this study established a chronic infection model in C57BL/6J mice using the virulent strain Brucella melitensis M16. Single-cell transcriptome sequencing (10x Genomics) was employed to map the heterogeneity of splenic immune cells. Whole-genome scanning and pangenomic analysis were performed on four strains with different virulence levels (M16, 544 A, M5, 104 M) using second-generation sequencing. Membrane/secreted proteins unique and conserved in virulent strains were screened as candidate antigens, prepared via prokaryotic expression systems, and their humoral and cellular immune levels were detected by indirect ELISA and flow cytometry. A stable chronic infection model was successfully constructed (bacterial load Log10 CFU > 4.5). Single-cell sequencing yielded 45,231 cells, annotated into 12 immune cell subpopulations, revealing significant expansion of Effector CD4 + T cells (P < 0.01) and high expression of the Ifng gene. Pangenomic analysis identified three candidate antigens (BMEI0021, BMEI1943, BMEI0367) that are 100
| The aim of this research was to create a sustainable biopesticide based on Trichoderma intended for use against the pathogen Fusarium solani in tomato. Individual and collective antagonistic potential of six Trichoderma spp. isolates was assessed through in vitro dual culture assays. Individual isolates showed inhibitory rates of 68.2 334.55× 10^9 CFU mL⁻¹, which exceeded the productivity of conventional media by 22–40 >0.98× 10^11 CFU mL⁻¹ biological activity for 360 days of storage at refrigeration temperatures, with more than 75 R^2>0.95 ), while carrier-specific regression modeling demonstrated that the optimized ‘mixture’ carrier significantly decelerated the decline kinetics compared to the non-formulated control. The results show that the formulated consortium offers an innovative, stable, high quality, and environmentally friendly substitute to chemical fungicides for use in Integrated Disease Management (IDM) programs.
Viral neurological infections are important causes of morbidity and mortality in horses worldwide. Herein, we describe an end-point multiplex PCR/RT-PCR for simultaneous and differential detection of major equine encephalitis-related agents: rabies virus (RABV), equine herpesvirus type 1 (EHV-1), alphaviruses [Venezuelan equine encephalitis virus (VEEV), Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV) and Madariaga virus (MADV)] and flaviviruses [West Nile virus (WNV), Saint Louis encephalitis virus (SLEV), Rocio virus (ROCV) and Japanese encephalitis virus (JEV)]. The multiplex assay successfully amplified all targets either individually or simultaneously: alphavirus (381 bp—experimentally evaluated for MADV and potentially applicable to EEEV and WEEV based on primer design and sequence conservation), EHV-1 (255 bp), RABV (173 bp), VEEV (119 bp), and flavivirus (97-101 bp—experimentally evaluated using ROCV, with the potential to also detect WNV, SLEV and JEV, based on primer design and sequence conservation). Furthermore, the assay demonstrated analytical sensitivity and specificity that support its use for the comprehensive etiological diagnosis of equine neurological diseases. Overall, the multiplex PCR/RT-PCR described here may contribute to the diagnosis of viral neurological infections in horses, reducing costs and turnaround time, while contributing to prevention and control measures.
Yeasts can produce microbial oil from hydrophobic substrates such as glycerol, a byproduct of the biodiesel industry that is often undervalued in the market. Yarrowia lipolytica is capable of degrading glycerol and is considered a model organism for studying lipid accumulation. Different yeast strains and culture conditions can result in varying lipid yields with distinct fatty acid profiles. Thus, in this study, five strains of Y. lipolytica were tested for microbial oil production using pure glycerol at temperatures of 15 °C and 25 °C. None of the isolates were considered oleaginous at 15 °C. However, at 25 °C, the isolates UFMG-CM-Y6114 (from cheese), UFMG-CM-Y4187 (from beach sand), and UFMG-CM-Y6189 (from Antarctica) produced more than 20
Meat products represent important vehicles for foodborne viral transmission, yet standardized detection methodologies for these complex matrices remain limited. This study systematically compared three viral recovery methods across nine meat products representing chicken, pork, and processed deli meat matrices: polyethylene glycol 6000 (PEG) precipitation, glycine buffer-chloroform (GBC) phase separation, and β-mercaptoethanol (B-M) chaotropic lysis. Using Murine Norovirus 1 (MNV-1) and Murine Hepatitis Virus 3 (MHV-3) as process controls, recovery efficiency was assessed by RT-qPCR. The B-M method demonstrated the most consistent performance, successfully detecting MNV-1 across all tested matrices and significantly outperforming PEG and GBC for MNV-1 in chicken and pork. Applying the B-M method to 25 commercial retail products revealed the genetic material of Hepatitis E virus (HEV) in four samples and Porcine Circovirus type 2 (PCV-2) in one sample, exclusively within pork products. These findings provide critical comparative performance data for method selection in viral surveillance of meat and document the occurrence of HEV and PCV-2 genetic material in commercial pork products from Santa Catarina, Brazil, highlighting a significant food and agricultural biosafety concern in this major meat-producing and exporting state.
Gonatobotryum is an anamorphic fungus reported mainly as a saprophyte, parasite, or endophyte. The genus has traditionally been identified based on morphological features, with its phylogenetic placement remaining uncertain due to the lack of molecular data. During the analysis of fungi obtained from mangrove sediments in Brazil, nine isolates were morphologically identified as Gonatobotryum and subsequently analysed using the internal transcribed spacer (ITS) region, including the intervening 5.8S nRNA gene and the nuclear ribosomal RNA large subunit (LSU) gene, leading to the description of a new species, Gonatobotryum mangrovei. Additionally, the type material of Gonatobotryum bahiense was re-evaluated regarding its phylogenetic placement. Here, we propose a new combination, Ophiostoma bahiense, to place this species within the genus. Our results clarify the phylogenetic position of Gonatobotryum and expand the current understanding of fungi in mangrove environments.
Nicotine-rich wastes from the tobacco industry represent an environmental liability but also a potential feedstock for value-added bioconversion. In this study, the biotechnological potential of Paenarthrobacter nicotinovorans ATCC 49919 for selective accumulation of 6-hydroxy-(L)-nicotine (6HLN), the first intermediate of the pyridine pathway, was evaluated under flask and bioreactor conditions. Two metabolic engineering strategies were explored: transcriptional silencing of the 6-hydroxynicotine oxidase gene (6hlnO) using a CRISPR/dCas9 system and overexpression of the nicotine dehydrogenase large subunit (ndhL) to enhance entry flux into the pathway. Among the tested strains, the ndhL-overexpressing derivative exhibited the highest 6HLN accumulation during growth (up to 1.78 g L⁻1; space–time yield 104.4 mg L⁻1 h⁻1). Resting-cell bioconversion experiments identified 100 g wet cell weight L⁻1 as an optimal biomass loading. Chemical inhibition of 6-hydroxy-L-nicotine oxidase with 0.8 mM ZnSO4 further expanded the 6HLN accumulation window without substantially impairing nicotine depletion. Scale-up experiments in a stirred bioreactor demonstrated effective conversion of both pure nicotine and tobacco-derived extracts, with matrix-dependent differences in conversion kinetics. Dissolved oxygen profiles correlated reproducibly with substrate depletion and product turnover, providing a potential online process control signature. Although not achieving near-stoichiometric yields reported for knockout-based systems, the described platform offers a controllable and feedstock-flexible approach for nicotine waste valorization.
HMG-CoA reductase inhibitors, commonly known as statins, effectively reduce low-density lipoprotein cholesterol levels in the blood, thereby playing a key role in the treatment of cardiovascular and cerebrovascular diseases. The biosynthesis of the compounds can be achieved via deoxyriboaldolase. In this study, a 672-bp gene coding 2-deoxyribose-5-phosphate aldolase (DERA) was identified from the genome of Bacillus altitudinis JYY-02 and overexpressed in Escherichia coli BL21(DE3). The recombinant DERA exhibited a molecular weight of 23.15 kDa and was purified by Ni-NTA affinity chromatography with a 12.9-fold increase in purity and a final yield of 51.2
Microorganisms capable of simultaneously achieving nitrogen removal and emerging organic contaminants (EOCs) degradation under carbon-limited conditions are highly desirable for wastewater treatment, however, such multifunctional performance remains poorly understood. Diclofenac (DCF), a frequently detected pharmaceutical with recognized environmental risks, is particularly recalcitrant to biological removal. In this study, an Alcaligenes sp. FDN-09 was identified as a strain capable of concurrent ammonium nitrogen removal and DCF attenuation under low C/N conditions. Optimal performance was achieved at C/N ratio of 4.0, with total nitrogen and DCF removal efficiencies of 63.3
In the paper industry, pulp bleaching is an essential step to increase the whiteness and brightness of paper, which is typically achieved using chlorine-based or oxidative chemicals that cause significant environmental pollution. In the present study, Bacillus tequilensis LXM 55 produced a cocktail of lignocellulolytic and hemicellulolytic enzymes. Solid-state fermentation (SSF) is a cost-effective and efficient method suitable for large-scale enzyme production. Therefore, the SSF process was optimized for the production of the enzyme cocktail employing traditional and statistical methods. Optimization resulted in a significant improvement in enzyme yields, with 34.0-, 22.85-, and 20.37-fold increases in enzyme yield for laccase (L) (4518.54 IU g⁻¹), xylanase (X) (2664.81 IU g⁻¹), and mannanase (M) (1448.42 IU g⁻¹), respectively. For commercial viability, the optimized process was successfully scaled up to a 1 kg substrate level without any significant loss in enzyme productivity. The enzyme cocktail (L+X+M) was applied to pulp bleaching, resulting in a 48
