Letters in Applied Microbiology最新文献

Common mycorrhizal networks (CMNs) facilitate nutrient transfer between plants, but their role in supporting non-mycorrhizal species remains largely unexplored. This study investigates the effect of CMNs on the growth and nutrient uptake of the non-mycorrhizal plant Chenopodium album in association with the mycorrhizal plant Parthenium hysterophorus. The treatments included C. album alone, C. album grown with P. hysterophorus to allow CMN formation, and C. album treated with fungicide to inhibit mycorrhizal activity. Results showed that CMN treatment significantly enhanced the plant growth and uptake of nutrient content (N and P) in C. album compared to the control. There was no mycorrhizal colonization in C. album, while high colonization in P. hysterophorus suggested that the enhanced growth in C. album was due to nutrient uptake transfer through the CMNs. The fungicide treatment resulted in reduced growth and uptake of nutrient content, providing further evidence that CMNs and mycorrhizal associations of mycorrhizal plants enhanced the growth of C. album. These findings provide the first evidence that CMNs can enhance the growth and nutrient uptake of non-mycorrhizal plants through associations with mycorrhizal partners.

Levan, a fructan-type polysaccharide with diverse applications in food, pharmaceuticals, and biotechnology, has garnered significant attention for its functional properties, such as prebiotic, immunomodulatory, antioxidant, and antimicrobial activities. In this study, the effects of fermentation temperature, sucrose concentration, and incubation time on the molecular weight of levan produced by Bacillus licheniformis fermentation were investigated. The results showed that as the temperature (37-50 °C) and sucrose concentration (300-500 g l-1) increased, the molecular weight of levan produced by the strain during fermentation decreased. At the same time, the molecular weight initially increased and then decreased with longer culture times, indicating that levan within a specific size range could be produced by controlling the fermentation conditions. In addition, the properties and characteristics of levan produced by fermentation at two molecular weights (HML and LML) were compared. The results showed that molecular weight significantly affected the micromorphology, thermal behavior, rheological properties, and prebiotic activity of levan. Therefore, this study demonstrated that Bacillus licheniformis SFLV-ZM107 can produce low molecular weight levan, and its molecular weight can be controlled through fermentation conditions. Consequently, the properties and functions of levan can be influenced, allowing the production of levans with the desired characteristics.

Levilactobacillus brevis YT108, identified for its ability to metabolize prebiotic xylo-oligosaccharides (XOS), emerges as a candidate for probiotic use in synbiotic food formulations. This study aimed to investigate the metabolic and genomic traits associated with XOS metabolism in YT108 and to assess its probiotic attributes through whole genome sequencing and in vitro assays. Strain YT108 exhibited robust growth kinetics on XOS as the sole carbon source, with a growth profile comparable to that on glucose, achieving a pH reduction to 4.68 and an OD600 nm of 1.603 after 48 h. Three key gene clusters (xylCDEPFRT, xylHTG, and xylABT) and key enzymes (1,4-β-xylosidase) were identified as potentially involved in XOS metabolism. In vitro assays confirmed the strain's remarkable physiological properties including tolerance to acid, bile, heat and NaCl, as well as resistance to simulated gastrointestinal juices and antioxidant capacity. Furthermore, strain YT108 was sensitive to five commonly used antibiotics and lacked transferable resistance genes. Taken together, these results highlight the potential of L. brevis YT108 as a probiotic candidate with beneficial traits for XOS utilization, suggesting its promising application in the formulation of next-generation synbiotic products.

This work aimed to improve some steps of the existing guidelines of the European Standards to obtain an Aspergillus brasiliensis ATCC 16404 spore suspension with >75% spiny spores without mycelia and a concentration of at least 1.5 × 108 CFU ml-1. Several manufacturers' combinations of "strain/medium" were assessed in terms of yield of spiny spores. Criteria to establish success included (i) the growth over different times of incubation (4, 7, and 10 days); (ii) the performance of two different filtration devices (fritted filters and cell strainers); and (iii) the fungal spores susceptibility after 4 days of incubation versus 7 days of incubation against a peracetic acid-based disinfectant. The best combination was "Microbiologics strain/Oxoid MEA" with 88.33% of spiny spores already after 4 days, and no statistical differences (P < .05) in terms of growth in the three time points were highlighted (from 1.85 × 108 CFU ml-1 to 2.21 × 108 CFU ml-1). Cell strainers gave a spore suspension much more concentrated (3.31 times) compared to fritted filters. Furthermore, the 4-day-old spore suspension showed the same susceptibility to disinfection when compared to a suspension whose culture was incubated for 7 days.

Root-lesion nematodes (Pratylenchus spp.) are significant plant parasites, causing substantial crop damage worldwide. This study aimed to characterize Pratylenchus spp. in New Zealand maize fields using molecular techniques and map their prevalence. Soil sampling from 24 maize fields across the North and South Islands provided 381 composite samples. Root-lesion nematodes were extracted using the sieving-centrifugal-sugar flotation method and differentiated into five morphospecies. Molecular characterization involved direct partial sequencing of the D2/D3 28S rDNA, ITS rDNA, and COX1 mtDNA regions using Sanger technology from a single nematode. Five Pratylenchus species were identified: P. neglectus, P. crenatus, P. thornei, P. penetrans, and P. pratensis, confirmed by phylogenetic analysis. Prevalence mapping showed P. neglectus and P. crenatus in all sampled fields, while P. thornei, P. penetrans, and P. pratensis were more localized. This study is the first to report these Pratylenchus species on maize in New Zealand and provides the first partial sequences of the D2/D3, COX1, and ITS regions for these species on maize in New Zealand. The findings highlight the diversity of Pratylenchus populations in New Zealand maize fields and emphasize the need for region-specific management strategies to mitigate crop damage.

This study evaluated a point-of-care device for wastewater-based epidemiology (WBE) of SARS-CoV-2 circulation. WBE is a critical tool but faces challenges such as laboratory infrastructure, sample transport, skilled personnel, and time-consuming methods. Currently, a rapid, portable solution for wastewater surveillance is lacking. From June to September 2022, the performance of the GeneXpert instrument was compared with an established in-house method for detecting SARS-CoV-2 in 151 wastewater samples across laboratory, field, and mobile testing environments. In the laboratory setting, GeneXpert showed 100% agreement in detection, with 94.6% of positive samples displaying a viral load difference of ± 1 log compared to the in-house method. Field testing demonstrated 90% agreement, with 92.6% of GeneXpert-positive samples showing similar log differences. In mobile testing, GeneXpert detected 62.5% of samples, and testing faced technical issues. Overall, GeneXpert displayed a limit of detection of 12 cpml-1 with results available in under an hour, making it a promising tool for rapid and deployable wastewater testing. This requires further validation while addressing technical challenges related to field and mobile settings.

This study was conducted to detect the occurrence and phenotypic resistance pattern of extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in livestock using docking-based analysis to reveal the classes of antibiotics against which ESBL-producers are active. Rectal swabs from healthy cattle (n = 100), goats (n = 88), and pigs (n = 66) were collected from backyard farms in Andaman and Nicobar Island (India). In total, 304 isolates comprising Escherichia coli (131), Salmonella (75), and Klebsiella pneumoniae (98) were recovered. The phenotypic resistance pattern showed that the highest resistance was found against erythromycin, followed by ampicillin/cloxacillin, ciprofloxacin, amoxicillin/clavulanic acid, and oxytetracycline. Screening of the isolates demonstrated maximum presence of blaTEM-Type, followed by blaCTX-M-Type, and blaSHV-Type. Sequence homology revealed the presence of CTX-M-15, SHV-228, SHV-40, and TEM-82. The possible interactions of CTX-M-15 with cephalosporins and SHV with carbapenems have been identified by docking analysis. The study revealed the occurrence of ESBL-producers with circulating emerging ESBL variants like SHV-40, along with the common variants with clinical relevance (CTX-M-15, TEM-82), highlighting the potential role of livestock as reservoirs for antimicrobial resistance genes. Identifying these ESBLs in livestock is crucial for understanding their contribution to the dissemination of antimicrobial resistant bacteria into the human food chain.

Quantitative polymerase chain reaction (qPCR) and digital PCR (dPCR) are applied for quantifying molecular targets in disease diagnostics, pathogen detection, and ecological monitoring. Uptake of dPCR is increasing due to its higher quantification accuracy relative to qPCR, which stems from its independence from standard curves and its increased resistance to PCR inhibitors. Throughput can be increased through multiplexing, which allows simultaneous quantification of multiple targets. However, multiplexing with dPCR faces unique challenges relative to qPCR. Here, we describe the three-phase development process of non-competing multiplex dPCR assays using target-specific fluorescently labeled hydrolysis probes. We highlight common challenges encountered, along with recommended solutions. Phase 1: In silico assay design; target-specific primers and probes are selected or designed, potential issues with primer and probe interactions are identified, and fluorophores and quenchers are chosen based on dPCR instrumentation. Phase 2: Wet-lab validation; assays are benchmarked using positive controls. Insufficient performance leads to assay redesign, as needed. Phase 3: Assay implementation; assay specificity and sensitivity are validated on relevant sample matrices. Finally, we provide recommendations on the future design and standardization of multiplexed dPCR assays, highlighting the need for better in silico predictions of assay performance, standardizing positive controls, and automating partition classification systems.

Essential oils are natural substances used as therapeutic agents and food preservatives to inhibit harmful microorganisms. This study aimed to assess the synergistic effect of Trachyspermum ammi essential oil and ampicillin on antibiotic-resistant gastrointestinal pathogens, including Escherichia coli, Enterococcus faecalis, Shigella flexneri, and Salmonella serotype Typhimurium. Using gas chromatography-mass spectrometry (GC-MS), the main components of T. ammi essential oil were identified as thymol, gamma terpenes, and cymene. The antibacterial and antibiofilm properties were evaluated by minimum inhibitory concentration (MIC), disk diffusion, and microtiter plate methods, revealing MIC values of 2, 1, 4, and 4 mg ml-1 for E. coli, E. faecalis, S. flexneri, and S. Typhimurium, respectively, and inhibition zones between 10 and 14 mm. Pathogens were examined for their biofilm-related virulence genes, including aggR, esp, icsA, and fliC, using real-time polymerase chain reaction (RT-PCR) in E. coli, E. faecalis, S. flexneri, and S. Typhimurium, respectively. The methyl thiazole tetrazolium (MTT) assay was used to evaluate the essential oil's effect on the viability of human embryonic kidney 293 (HEK293) cells, which showed cell viability of over 80%. The combination of T. ammi oil and ampicillin demonstrated a synergistic effect, and biofilm formation was inhibited. E. faecalis exhibited the greatest sensitivity, while S. flexneri exhibited the lowest sensitivity.