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PubMed2026

Soil Acidification Enriches Antibiotic Resistome.

Soil acidification represents a critical global change issue. Its impacts on antibiotic resistance genes (ARGs), however, remain poorly understood. Here we first analyzed a published global dataset comprising 1012 sampling sites and found a significant negative correlation between soil pH and the total richness and relative abundance of ARGs. To validate the observed pattern, we subjected three soils (with initial pH 7.8-7.9) each to 4 acidification levels (pH 7, 6, 5, and 4) for 30 days and subsequent recovery for another 30 days in microcosms. Shotgun metagenomic sequencing revealed that acidification (pH 6, 5, and 4) significantly increased the total richness and relative abundance of ARGs, as well as the relative abundances of 175 ARG subtypes, across all three soils. These 175 acidification-enriched ARGs together accounted for more than 70% of all the ARGs under severely acidified conditions (pH 5 and 4). Moreover, 93% of the bacteria carrying acidification-enriched ARGs also carried various virulence factor genes homologs associated with pathogenicity in reference databases, resulting in increased risk score. The total relative abundance of the acidification-enriched ARGs was primarily associated with changes in bacterial community traits (community composition, acidification-enriched metabolic functions, and genome size), followed by the increase in availability of toxic metals. When soil recovered from severe acidification (pH 5 and 4), the total relative abundance of the acidification-enriched ARGs significantly declined, demonstrating that the effect of soil acidification is partially reversible. This study reveals an underrecognized risk of ARGs caused by soil acidification, highlighting that the prevention and mitigation of soil acidification are crucial for combating antibiotic resistance.

Hydrogen-Ion Concentration↗
PubMed2026

Chemometric insights into Lactiplantibacillus plantarum effects on onion (Allium cepa L.) metabolism and antidiabetic activity under cadmium stress.

Cadmium (Cd) is a toxic heavy metal that causes severe physiological damage in plants, inhibiting growth and ultimately reducing crop yield. Lactic acid bacteria regulate Cd availability through bioaccumulation and biosorption. This study evaluated the Cd tolerance of Lactiplantibacillus plantarum 10CH by determining its survival capacity under Cd stress and its potential to mitigate Cd-induced stress in onion (Allium cepa L.). The bacterial strain tolerated Cd concentrations up to 100 µM, and whole-genome sequencing identified genes involved in Cd biosorption, accumulation, and efflux. Exposure of onion to increasing CdCl2 concentrations significantly reduced root and shoot biomass. Inoculation with Lb. plantarum 10CH alleviated Cd stress at 100 µM, enhancing root and shoot biomass, reducing Cd accumulation, lowering oxidative damage markers, and stimulating antioxidant enzyme activities. Metabolic profiling revealed that Cd stress significantly reduced primary metabolites and amino acids, particularly at 100 µM, while bacterial inoculation restored key amino acids and peptides, including arginine, tyrosine, and glutamic acid. Chemometric analysis using unsupervised (PCA) and supervised (OPLS-DA) models revealed clear metabolite variation among untreated, Cd-stressed, and bacterial inoculated Cd-stressed onion leaves. Furthermore, leaf extracts exhibited α-glucosidase inhibitory activity, with the highest activity in control plants (IC50 = 425.2 ± 0.5 µg/mL). Cd-stressed plants showed moderate antidiabetic activity, which was significantly reduced by bacterial inoculation. Overall, these findings demonstrate that Lb. plantarum 10CH can survive under Cd stress and alleviates Cd-induced stress in onion, highlighting its potential as a bioinoculant to mitigate heavy metal stress.

Onions↗
PubMed2022

Battle for Metals: Regulatory RNAs at the Front Line.

Metal such as iron, zinc, manganese, and nickel are essential elements for bacteria. These nutrients are required in crucial structural and catalytic roles in biological processes, including precursor biosynthesis, DNA replication, transcription, respiration, and oxidative stress responses. While essential, in excess these nutrients can also be toxic. The immune system leverages both of these facets, to limit bacterial proliferation and combat invaders. Metal binding immune proteins reduce the bioavailability of metals at the infection sites starving intruders, while immune cells intoxicate pathogens by providing metals in excess leading to enzyme mismetallation and/or reactive oxygen species generation. In this dynamic metal environment, maintaining metal homeostasis is a critical process that must be precisely coordinated. To achieve this, bacteria utilize diverse metal uptake and efflux systems controlled by metalloregulatory proteins. Recently, small regulatory RNAs (sRNAs) have been revealed to be critical post-transcriptional regulators, working in conjunction with transcription factors to promote rapid adaptation and to fine-tune bacterial adaptation to metal abundance. In this mini review, we discuss the expanding role for sRNAs in iron homeostasis, but also in orchestrating adaptation to the availability of other metals like manganese and nickel. Furthermore, we describe the sRNA-mediated interdependency between metal homeostasis and oxidative stress responses, and how regulatory networks controlled by sRNAs contribute to survival and virulence.

Bacteria↗