Folia microbiologica最新文献

This study focuses on preparing Ag/Ag₂O nanoparticles (NPs) by a one-pot method and anchors the CeO₂ nanospheres as antimicrobial agents. XRD patterns revealed the successful preparation of Ag/Ag₂O/CeO₂ NPs. Additionally, SEM and TEM images exhibited that the Ag/Ag₂O/CeO₂ NPs are aggregated with a spherical shape in the nanoscale range. By looking at how well they fight bacteria, the smallest amount needed to stop growth, and their ability to prevent biofilm formation, we tested how effective Ag/Ag₂O/CeO₂ NPs are against bacteria that cause serious infections and unicellular harmful fungi. The membrane leakage experiment was used to investigate a possible mechanism of antibacterial behavior. The synthesized Ag/Ag₂O-CeO₂ NPs showed strong antimicrobial effects against all the bacteria and unicellular fungi we tested. At a concentration of 250 μg/mL of CeO₂ NPs, the maximum ZOI of approximately 19.0 mm was seen against Candida albicans, and 17.0 mm against Bacillus subtilis at the same concentration. E. coli was detected in the 16.0 mm ZOI during the action against K. pneumoniae. On the other hand, the largest ZOI of roughly 26.0 mm was tested against B. subtilis and C. albicans at 250 μg/mL of Ag/Ag₂O NPs. This was followed by ZOIs of 21.0 mm against C. tropicalis, 20.0 mm against K. pneumoniae and E. cloacae, and 19.0 mm against S. epidermidis. The Ag/Ag₂O-CeO₂ NPs showed a range of activities at 250 μg/mL against B. subtilis (34.0 mm ZOI) and C. albicans (33.0 mm ZOI). Ag/Ag₂O-CeO₂ NPs, however, had the same effect on E. coli, P. fluorescens, and S. epidermidis (25.0 mm ZOI). The final result showed that Ag/Ag₂O-CeO₂ NPs exhibited 22.0 mm ZOI activity against K. pneumoniae and 21.0 mm ZOI activity against E. cloacae. The promising findings suggested that the Ag/Ag₂O-CeO₂ NPs can be used against pathogenic bacteria in biomedical fields.

The plant microbiomes consist of a myriad of microorganisms that inhabit and interact with plant tissues and play pivotal roles in improving crop productivity and sustainability. These microbiomes constitute bacteria, fungi, archaea and viruses that have coevolved and supported plants inhabiting the Earth for millions of years. Among these, bacterial members play major functional roles in fostering plant growth and are regarded as plant growth-promoting bacteria (PGPB). One of the major bacterial genera of the plant microbiome that colonizes the entire plant system is the genus Methylobacterium. The genus Methylobacterium is categorized as a member of the class Alphaproteobacteria and is distinguished by its pink pigmentation, which is a result of the synthesis of carotenoids, mainly xanthophiles. Members of the Methylobacterium genus are commonly known as pink-pigmented facultative methylotrophs, which are ubiquitous in nature and have gained significant importance in crop production in various agricultural ecosystems because of their versatile ability to promote plant growth and enhance stress tolerance. They have the unique ability to utilize single-carbon compounds that are released during plant cell metabolism, improve plant growth, siderophore and phytohormone (auxin and cytokinin) production, and nitrogen fixation; phosphorous and zinc solubilization and induced systemic resistance against phytopathogens; protective biofilm formation; and the production of 1-aminocyclopropane-1-carboxylate deaminase to increase stress tolerance  and carotenoid production for UV stress tolerance. Owing to its use as a biostimulant, biofertilizer and biocontrol agent, Methylobacterium has potential applications in agriculture for increasing soil health, crop productivity and environmental sustainability. This review provides broad perspectives on the multifaceted role and sustainable application of Methylobacterium in climate-smart agriculture.

The current investigation aimed to highlight the potential of probiotics isolated from lactic acid bacteria of different Algerian ecosystems as antioxidant and antidiabetic agents. Fifty-four strains from different ecosystems were isolated anaerobically. The subsequent steps involved comprehensive characterization and in vitro assessments, including assays for scavenging DPPH and ABTS•+ radicals, measuring ferric ion reducing power (FRAP), and assessing the impact of the strains on the α-amylase enzyme. Additionally, the hydrophobicity potential, aggregation and coaggregation capacities, antibacterial activity, and absence of hemolytic activity were investigated. Ten (10) out of the fifty-four (54) strains exhibited characteristics of probiotics like resistance at a low gastric pH (2.0-3.0) (> 55% survival rate) and survival under different concentrations of NaCl and bile salts 0.3%-1% (> 80% survival rate). All the isolated strains exhibited high hydrophobicity potential, remarkable aggregation and coaggregation capacities, and antibacterial activity but no hemolytic activity. Because of the antioxidant capacity of the selected strains, every strain seems to be capable of efficiently scavenging DPPH and ABTS•+ radicals, superoxide dismutase and hydroxyl radical scavenging activity, and high resistance to H₂O₂. The findings of this study strongly suggest that the identified strains hold significant promise as potential probiotic candidates. Their observed capabilities make them particularly valuable in addressing oxidative stress and associated conditions, such as diabetes.

Around 55% of the rice soils in West Bengal, the highest rice-producing state in eastern India, are deficient in zinc (Zn), leading to Zn malnutrition among its population due to huge reliance on rice for calories. The present investigation tested the feasibility of native zinc-solubilizing bacteria (ZnSB) to improve the Zn bioavailability and subsequent biofortification of rice grown in Gangetic alluvial soils that are low in Zn. Initially, 56 bacterial isolates were recovered from the rice rhizosphere of Zn-deficient soils, and 20 were found to solubilize insoluble Zn in agar plates. Among the 20 bacterial strains, Zn solubilizing potential was maximum for the isolate Burkholderia cepacia strain K1. It showed 775% Zn solubilizing efficiency, releasing 576.67 µg/mL Zn from zinc oxide in liquid medium and lowering the solution pH by 2.87 units. Principal component analysis revealed that K1, along with strains K2 and B4, produced the best results when testing Zn solubilization ability alongside indole-3-acetic acid production (18.5-24.6 µg/mL) and metabolic adaptability for all tested carbon sources. In the pot experiment, root biopriming with K1 significantly increased soil available Zn by 105.8%, rice grain yield by 19.9%, and grain Zn concentration by 36.3% over the control treatment, which produced 12.69 g grain/pot with a Zn concentration of 24.33 µg/g grain. The experimental findings illustrate that native ZnSB strains K1, K2, and B4 shows promise for reducing Zn deficiency in rice fields as a sustainable solution while managing malnutrition and soil health.

Pseudomonas aeruginosa is an important opportunist pathogen responsible for community-acquired and nosocomial infections. The intestinal carriage of P. aeruginosa is likely due to its opportunistic nature. The aim of this study was to compare phenotypic and genotypic characteristics of P. aeruginosa recovered from stool of intestinal carriers with those isolated from various clinical specimens. Twenty- four fecal P. aeruginosa isolates obtained from 148 stool samples (74 healthy individuals and 74 patients with colonic disease) and 26 clinical P. aeruginosa isolates recovered from various clinical specimens other than stool, were investigated. Antimicrobial susceptibility, biofilm-forming ability using phenotypic methods and presence the exoY, algD, toxA, exoS, exoU, lasB, exoT genes were determined using polymerase chain reaction. The frequency of fecal carriage of P. aeruginosa was determined 16.2%. All fecal isolates were susceptible to ceftazidime and colistin, whereas all clinical isolates were susceptible only to colistin. There were no significant differences in multidrug- resistant (MDR) phenotypes between the clinical and fecal isolates. No significant differences in biofilm production were observed among isolates from healthy individuals compared with those from patients with colonic disease. However, differences were observed between clinical and fecal isolates regarding the presence of the algD and exoU genes (P ≤ 0.05). A significant difference was also found in the present of the exoU gene between MDR fecal and MDR clinical isolates (P = 0.007). The high prevalence of virulence factors in both fecal and clinical isolates emphasizes the importance of fecal P. aeruginosa as same as clinical isolates.

Algeria imports all of its enzymes for use in different fields, which causes a ‎serious economic problem as the cost of these enzymes is continuously rising. New enzymes with efficient and unique properties are always sought to meet the specific needs of various industry sectors. This study aimed to investigate the purification and characterization of α-amylase from the Algerian Geotrichum candidum PO27, and its potential application as a desizing agent in the textile industry. This enzyme was purified 6.73-fold in two process steps: concentration by ultrafiltration, followed by exclusion ‎chromatography, achieving a final recovery of 9.1%. The results showed that its molecular weight was estimated for the first time by SDS-‎PAGE as 19.2 kDa. Physicochemical characterization of purified enzyme revealed optimal activity at pH 5 and 70 °C, thermostability properties, and high stability in the presence of Mg²⁺ and Tween 80. It was also found to be resistant to surfactants and organic solvents. The enzyme exhibited a maximum velocity (V_max) of 588.23 U/mL ‎and a high affinity for soluble starch, with a Michaelis Menten constant (K_m) of 0.114 mg/mL, values not previously reported. The enzyme showed notable efficacy in cotton desizing at room temperature, demonstrating its potential for efficient, low-cost industrial applications.

Bacterial communities in the gastrointestinal tract (GIT) play a critical role in the health and physiology of vertebrates, responding to multiple intrinsic and extrinsic factors that modulate their structure and function. However, little is known about how these factors are associated with the dynamics and composition of these bacterial communities, especially in crocodilians. In this study, the structure of oral and cloacal bacterial communities in the GIT of Crocodylus acutus was examined through 16 S rRNA gene sequencing. The influence of factors such as age, sex, season, and anatomical location was evaluated. A total of 54 oral and cloacal samples from 27 adult and juvenile specimens from a captive population in Sinaloa, Mexico, were analyzed. Forty-two bacterial phyla were identified, with Pseudomonadota, Bacillota, and Bacteroidota being the most abundant. Significant differences in bacterial composition and diversity were detected between age groups and body regions, with greater diversity in adult specimens. Functional analysis predicted a predominance of metabolic pathways associated with amino acid and carbohydrate metabolism. This study establishes that age and anatomical site are key determinants in the structure of bacterial communities in C. acutus in captivity, providing the first comprehensive characterization for the species. These results establish a fundamental baseline for future comparative research with wild populations, as well as for the development of management and conservation strategies.

The concerted overexpression of multiple efflux pumps in Pseudomonas aeruginosa now represents a key driver of multidrug resistance (MDR), progressively undermining the efficacy of conventional antibiotic therapies. The transferability of plasmid pXM8-2 was assessed by conjugation experiments. The antimicrobial susceptibility of strains P113, P118, T117, and XM8 was determined using the BioMerieux VITEK-2 system in conjunction with the disk diffusion method. β-lactamase or carbapenemase production was detected per CLSI guidelines. Efflux pump gene expression was quantified by quantitative real-time PCR, and O-antigen serotyping was performed phenotypically with specific antisera and genotypically via bioinformatics tools. Whole-genome sequencing using Illumina and nanopore platforms revealed a comprehensive profile of antibiotic resistance genes. Phenotypically, strains P113, P118, and T117 were resistant to all antibiotics tested, consistent with their genotypes. In contrast, strain XM8, which also harbored numerous resistance genes, remained susceptible to colistin. All attempts to transfer the pXM8-2 plasmid via conjugation were unsuccessful. The studied strains exhibited a MDR phenotype, primarily conferred by the overexpression of efflux pumps (e.g., MexAB-OprM, MexCD-OprJ, MexXY, MexEF-OprN) and inactivation of the oprD. Genotypic characterization identified strains P113, P118, and T117 as ST11/O3 (ExoS⁺/ExoU^-), whereas XM8 was ST385/O6 (ExoS⁺/ExoU^-). Evolutionary analysis indicated the global dissemination of XM8-like clones, with a pronounced peak in 2023-2024. Crucially, the MDR of XM8 was further exacerbated by antibiotic resistance genes located on its non-transferable plasmid, pXM8-2. Enhanced surveillance and preemptive containment measures are urgently needed to mitigate the public health threat posed by these resistant lineages.

Despite being an abundant metal, nature evolved to exclude aluminium (Al) from living organisms. In addition, the complex chemistry of this element makes it a challenging case for researchers. At physiological pH, Al has strong affinity to oxygen donors and negatively charged molecules such as proteins, nucleotides and cellular components bearing phosphates and carboxylic groups. Because of its widespread industrial use, living organisms are increasingly exposed to soluble forms of this light metal and environmental bacteria are in the front line. In this work, we show the disruptive effect of Al at physiological pH on the cellular morphology of Pseudomonas putida KT2440 and on the integrity of its mature biofilms. Proteomic studies revealed that an exposure to 0.78 mM of the aluminium compound used in this study significantly affected key proteins and enzymes involved in the TCA cycle, the respiratory chain, the maintenance of the cell's membrane and the transmembrane transport systems. The expression levels of major metal-resistance proteins (e.g., P-type ATPases and RND tripartite efflux pumps) was not affected, contrary to those of methyltransferases and systems involved in the metabolism of phosphate that might be involved in the maintenance of low Al concentration in the cytoplasm.