The research team, led by Mingjing Li of Jilin Agricultural University together with colleagues at the Heilongjiang Academy of Agricultural Sciences, set out to address a gap that has frustrated both ecologists and crop breeders. It is well established that rhizosphere bacteria, the microbial community hugging the root surface and the thin layer of soil it influences, play important roles in helping plants cope with environmental stress. What has remained poorly understood, however, is how the regulatory interplay between the plant and its microbiome differs between genotypes that tolerate saline-alkali conditions and those that succumb to them.

To probe this question, the researchers compared three wild soybean genotypes: two designated as saline-alkali tolerant, labeled 100 and 142, and one saline-alkali sensitive type, labeled 047. By growing these types under control conditions and under saline-alkali treatment, and then analyzing the bacterial communities in the surrounding soil alongside measurements of soil chemistry and enzyme activity, the team could trace how each genotype’s microbial partnership shifted as stress mounted. The approach allowed them to connect changes in microbial community structure with tangible shifts in soil functionality.

One of the first signals emerged from soil nitrogen chemistry. The tolerant types, 142 and 100, maintained significantly higher contents of ammonium nitrogen (NH4+) in their rhizosphere soil than the sensitive type 047. Ammonium is a preferred nitrogen source for many plants and microbes, and its elevated presence in the tolerant genotypes hints at enhanced nitrogen cycling in the soil surrounding their roots. Because nitrogen availability is tightly coupled to microbial activity, this difference suggests that tolerant wild soybeans may cultivate a soil environment that better sustains nutrient supply even when salt and alkali pressures would otherwise suppress it.

Intriguingly, the overall alpha diversity of bacteria, a measure of how many different bacterial types are present within a sample, did not differ dramatically between the sensitive and tolerant soybean types. In other words, the tolerant plants were not simply hosting more diverse microbial communities. The critical distinction lay instead in the structure of the community, meaning which specific bacterial groups dominated the rhizosphere. This finding challenges the intuitive assumption that diversity alone equals resilience, and instead highlights community composition, the identity of the players, as the decisive variable.

At the phylum level, the tolerant genotypes showed enrichment of Pseudomonadota, Bacteroidota, and Dependentiae, while Chloroflexota was less abundant compared with the sensitive type. These shifts are meaningful because different bacterial phyla carry different metabolic repertoires. Pseudomonadota, for example, includes many species known for rapid growth, nutrient cycling, and plant growth-promoting traits. The enrichment of such groups around tolerant roots suggests the tolerant plants may actively favor microbes that contribute to stress alleviation and nutrient mobilization.

Drilling down to the genus level revealed even finer patterns. Under normal, unstressed conditions, the genus Pseudomonas was enriched in the sensitive genotype 047, while an unclassified member of the family Vermiphilaceae was enriched in tolerant genotype 142. When saline-alkali stress was applied, the picture shifted again: norank_f_Saprospiraceae and norank_f_Vermiphilaceae became enriched in the tolerant genotype 142, whereas Aggregatilinea and norank_f_Anaerolineaceae were less abundant in tolerant genotypes compared with the sensitive one. These microbial signatures, some rising and others falling in tandem with stress, provide a detailed fingerprint of how the rhizosphere community reorganizes around roots that are coping versus roots that are struggling.

The study also identified the soil factors most tightly linked to these community shifts. Soil ammonium nitrogen, alkaline phosphatase activity (AP), and L-leucine aminopeptidase activity (S-LAP) emerged as important variables associated with changes in microbial community structure. Both enzymes are workhorses of soil nutrient cycling: alkaline phosphatase liberates phosphate from organic compounds, while leucine aminopeptidase breaks down proteins into amino acids that plants and microbes can absorb. Their prominence in explaining community variation ties the microbial reorganization directly to soil nutrient dynamics, painting a coherent picture of a feedback loop between plant stress tolerance, enzyme activity, and bacterial composition.

Perhaps most striking was the evidence on soil functionality. Under control conditions, soil functionality was significantly higher in tolerant type 100 than in sensitive type 047. Under saline-alkali treatment, both tolerant types, 100 and 142, showed elevated functionality relative to the sensitive type. Soil functionality, which integrates the capacity of the soil to support nutrient cycling, enzyme-mediated transformations, and biological activity, is widely regarded as a cornerstone of ecosystem health. The observation that tolerant wild soybeans sustain or even boost this functionality under stress suggests that the plant-microbe partnership is not a passive byproduct of salinity but an active component of tolerance itself.

Taken together, the authors conclude that soil functionality can be explained by changes in bacterial community structure, and that wild soybeans may actively reshape their soil microbial communities and their functionality as a strategy to resist saline-alkali stress. The implications ripple outward in several directions. For breeders, the microbial signatures enriched in tolerant genotypes could serve as markers for selecting resilient lines, or as clues for designing synthetic microbial communities that boost salt tolerance in cultivated soybean, a crop of enormous global importance for food and feed. For soil scientists, the identification of ammonium nitrogen and specific extracellular enzymes as key mediators reinforces a growing recognition in the field that microbial community composition, rather than diversity metrics alone, underpins ecosystem multifunctionality. And for anyone worried about the spread of saline-alkali soils, the message is quietly hopeful: the genetic resources of wild relatives like Glycine soja, paired with the microbes they recruit, may hold the keys to keeping farmland productive as soils grow saltier. As the authors’ results show, the roots of resilience may be planted long before the first salt crystal hits the leaf.

Subject of Research: The response of rhizosphere soil microbial diversity and functionality to saline-alkali stress in wild soybean

Article Title: Response of soil microbial diversity and functionality to saline-alkali in wild soybean (Glycine soja)

Article References: Li, M., Wang, S., Sun, S., Liu, M., Fan, C., Liang, W., Ji, X., & Liu, J. (2026). Response of soil microbial diversity and functionality to saline-alkali in wild soybean (Glycine soja). Plant and Soil. https://doi.org/10.1007/s11104-026-09090-6

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09090-6

Keywords: wild soybean, Glycine soja, saline-alkali stress, rhizosphere microbiome, soil bacteria, microbial community structure, soil enzymes, alkaline phosphatase, leucine aminopeptidase, ammonium nitrogen, soil functionality, plant stress tolerance

The trial enrolled adult patients scheduled for complex cardiac procedures who were considered at high risk of losing kidney function. To qualify, participants had to have pre-existing renal impairment, defined by an estimated glomerular filtration rate between 25 and 65 mL/min/1.73 m², calculated using the 2021 CKD-EPI formula without race correction. Eligible operations were those associated with prolonged exposure to the heart-lung machine, including coronary artery bypass grafting with three or more distal anastomoses, combined bypass and valve surgery, or aortic valve surgery with aortic root replacement. Patients whose kidney risk stemmed from other mechanisms, such as cardiogenic shock, sepsis, endocarditis or deep hypothermic circulatory arrest, were excluded, sharpening the focus on surgery-driven injury.

Between December 2023 and September 2025, 244 patients were randomized across European cardiothoracic centers. Of these, 204 received both study infusions and formed the per-protocol analysis set: 109 were treated with ilofotase alfa and 95 with placebo. Each patient received two intravenous doses of 128 milligrams, the first within six hours before the initial incision and the second within two hours after the sternum was closed, a strategy intended to have the enzyme circulating before and immediately after the ischemic and inflammatory insult. The trial was stratified by baseline kidney function and type of surgery, and blinding was strictly maintained, even prohibiting serum alkaline phosphatase measurements within fourteen days of dosing to prevent accidental unmasking.

The primary endpoint was the serum creatinine ratio, the highest creatinine value measured within five postoperative days divided by the preoperative baseline. The investigators chose this continuous measure deliberately: unlike the binary diagnosis of acute kidney injury, it can detect smaller shifts in renal function, accounts for each patient’s starting point, and correlates with longer-term outcomes. In the ilofotase alfa group the mean ratio was 1.21, against 1.27 for placebo, a numerical difference of roughly five percent that carried no statistical weight (p=0.31). Daily creatinine trajectories overlapped almost completely across the first five days after surgery, and no subgroup, examined by eGFR, sex, surgical type or bypass duration, showed a clear therapeutic signal.

The secondary endpoint, major adverse kidney events through day 60, or MAKE60, told the same story. This composite captured a drop of at least 25 percent in eGFR relative to baseline at day 60, initiation of renal replacement therapy, or death within sixty days. It occurred in 15.9 percent of ilofotase alfa patients and 15.4 percent of placebo patients, with an adjusted odds ratio of 0.94 (p=0.87). A win-ratio analysis weighting mortality, dialysis and eGFR decline in clinical priority order also came back null at 0.95. Exploratory KDIGO-based acute kidney injury rates were 29.4 percent versus 35.8 percent, again not significant, and median intensive care stays were identical at three days in both arms.

Safety, at least, was reassuring. Adverse event rates were comparable between groups, with 61.6 percent of treated patients experiencing at least one adverse event and 18.8 percent a serious event, versus 64.8 and 19.4 percent on placebo. None of the events were judged related to the drug, and no second dose was ever withheld for safety reasons. Anti-drug antibodies appeared in 21 subjects, predominantly at very low titers and without any discernible effect on pharmacokinetics, ruling out immunogenic interference. Measurement of ilofotase alfa concentrations revealed a median of 450 ng/mL on the first postoperative day, well above the 170 ng/mL threshold previously associated with clinical benefit, and exposure-response analyses showed no correlation between drug levels and the creatinine ratio.

Why did a therapy that protected kidneys in animal models of ischemia-reperfusion and in septic patients fail here? The investigators systematically ruled out the most obvious explanations. Underdosing seems unlikely given the plasma concentrations achieved. Mistimed treatment is equally implausible, because elective surgery offers a predictable window of injury and patients had therapeutic drug levels before the first incision. An assessment window of five days is arguably short for a lagging biomarker like creatinine, yet the absence of any signal in MAKE60 at two months argues against a delayed benefit that the study simply missed, even though it was not powered for that endpoint.

That leaves biology. Cardiac surgery-associated acute kidney injury is a notoriously multifactorial entity, driven by hemodynamic swings, hemolysis, oxidative stress, complement activation, nephrotoxin exposure and the systemic inflammatory storm triggered by the cardiopulmonary bypass machine. Neutralizing damage-associated and pathogen-associated molecular patterns, the mechanism through which alkaline phosphatase exerts its detoxifying effect, may simply be insufficient to prevent downstream organ damage when so many injurious pathways operate in parallel. The contrast with sepsis-associated kidney injury, where ilofotase alfa enhanced creatinine clearance recovery in earlier phase 2 and phase 3 work, suggests these are fundamentally distinct clinical syndromes whose treatments may not transfer across settings.

There is one tantalizing thread left for future research. In subgroup analysis, patients with longer aortic cross-clamp times, and therefore longer periods of renal ischemia, showed a tendency toward benefit that did not reach statistical significance. Whether the very highest-risk subsets, perhaps those with cross-clamp times well beyond the mean of roughly one hour seen in this cohort, could still derive meaningful protection remains an open question. Detecting the modest five percent effect actually observed would demand more than 2,000 patients, raising hard questions about whether such a trial would be feasible or clinically worthwhile in the absence of longer-term improvement.

The study also highlights a methodological innovation with broader implications: the serum creatinine ratio as a sensitive, continuous trial endpoint that captures mild renal impairment below the diagnostic threshold of acute kidney injury. Small creatinine rises are known to predict chronic kidney disease and mortality, making this a potentially valuable tool for future nephroprotection studies. For now, however, the clinical message is clear. With roughly 30 percent of cardiac surgery patients still developing acute kidney injury, mortality reaching 60 percent among those needing dialysis, and no approved pharmacological prevention anywhere on the horizon, clinicians are left with supportive measures, meticulous hemodynamics, nephrotoxin avoidance and careful fluid management, while researchers confront the uncomfortable truth that inflammation is only one thread in a tangled pathophysiological web.

Subject of Research: A phase 2 trial testing ilofotase alfa for prevention of acute kidney injury after open heart surgery

Article Title: A multicenter randomized, double-blinded placebo-controlled phase 2 trial to evaluate safety and efficacy of ilofotase alfa in patients at risk for kidney injury following open heart surgery

Article References: A multicenter randomized, double-blinded placebo-controlled phase 2 trial to evaluate safety and efficacy of ilofotase alfa in patients at risk for kidney injury following open heart surgery. (n.d.). https://doi.org/10.1007/s00134-026-08596-y

Image Credits: AI Generated

DOI: 10.1007/s00134-026-08596-y

Keywords: acute kidney injury, cardiac surgery, ilofotase alfa, alkaline phosphatase, cardiopulmonary bypass, clinical trial, phase 2, MAKE60, serum creatinine, renal protection, intensive care, nephrology

Persister cells are not resistant bacteria in the classical genetic sense. Instead, they are metabolically quiescent variants within an otherwise genetically identical population that temporarily shut down the processes antibiotics usually attack. Because most antibiotics target actively growing cells—cell wall synthesis, DNA replication, protein production—dormant persisters simply wait out the assault and repopulate the infection afterward. The phenomenon was first described in the 1940s, yet the molecular switches that govern how many cells enter this state remain incompletely mapped, particularly in K. pneumoniae, a leading cause of hospital-acquired pneumonia, urinary tract infections, and bloodstream infections.

To find new regulators of persistence, the research team, led by Yanxin Sun and Yumei Zhang with collaborators across several institutions in Shandong and Zhejiang provinces, compared gene expression during the emergence and recovery of persister populations. One gene stood out: phoU, which encodes a protein belonging to the phosphate-specific transport system. PhoU had been implicated in persister formation in Escherichia coli before, but its role in K. pneumoniae—and the downstream pathway through which it might act—was unclear.

The researchers used CRISPR-Cas9 gene editing to delete phoU from K. pneumoniae strain ATCC 700603, creating a knockout strain they could compare directly with the wild-type parent. They also constructed a complemented strain in which phoU was restored, as well as overexpression strains carrying extra copies of phoU, metE, or phoA—two genes that would soon prove central to the story. This panel of strains allowed the team to separate the effects of losing the gene from the effects of the surrounding genome and to test whether specific downstream functions could rescue the knockout’s defects.

The first surprise was what did not change. The ΔphoU strain grew at essentially the same rate as the wild type and showed no meaningful shift in baseline antibiotic susceptibility. In other words, PhoU is not a general housekeeping factor and its absence does not make the bacterium more fragile in ordinary conditions. What changed was the knockout’s ability to form persisters. When cultures were exposed to levofloxacin, a fluoroquinolone that targets DNA gyrase, or tobramycin, an aminoglycoside that attacks the ribosome, the ΔphoU strain produced significantly fewer surviving persister cells than the wild-type or complemented strains. Two antibiotics with completely different cellular targets produced the same result, suggesting that PhoU influences a shared upstream state—dormancy itself—rather than a drug-specific defense.

To understand how a phosphate transport protein could control dormancy, the team turned to metabolomics and transcriptomics. Untargeted metabolomic profiling, later deposited in the EMBL-EBI MetaboLights database, and genome-wide expression analysis revealed that deleting phoU downregulated two genes in particular: metE, which encodes the cobalamin-independent methionine synthase responsible for producing the amino acid methionine, and phoA, which encodes alkaline phosphatase, a classic marker of the phosphate starvation response. Methionine biosynthesis has previously been tied to stress tolerance in other bacteria; impaired methionine synthesis can lead to homocysteine accumulation and heightened sensitivity to environmental stress. Alkaline phosphatase, meanwhile, connects PhoU to the Pho regulon, the phosphate-sensing network that is increasingly recognized as a regulator of bacterial virulence and survival physiology.

The team then asked whether PhoU’s effect on persisters ran through biofilms. Biofilms—structured bacterial communities wrapped in extracellular polymeric substances—are well known refuges for tolerant cells, and PhoU is a component of the phosphate system long linked to biofilm regulation. The ΔphoU strain indeed formed weaker biofilms and produced less extracellular polymeric substance than the wild type, the complemented strain, and the overexpression strains. But the researchers made a critical distinction here. When they restored metE or phoA expression in the knockout background, biofilm formation and persister levels both partially recovered, yet further analysis indicated that the reduction in persisters was primarily attributable to metabolic defects in the free-swimming, planktonic cells—specifically impaired methionine synthesis and a weakened stress response—rather than to the reduced biofilm mass itself. Biofilm deficiency, in their interpretation, is a parallel phenotype of phoU loss, not the cause of persister decline.

That distinction matters clinically. If persister formation depends on the metabolic state of individual planktonic cells rather than on the architecture of a biofilm, then anti-persister therapies need not penetrate or dismantle biofilms to be effective. Targeting PhoU or its downstream partners—MetE in methionine metabolism and PhoA in the phosphate stress response—could, in principle, strip K. pneumoniae populations of their dormancy capacity even outside the protective matrix of a biofilm. The authors frame PhoU and its transcriptional targets as potential therapeutic vulnerabilities: drug candidates that force persisters out of hiding, or adjuvants that make conventional antibiotics lethal to the full population rather than only its active fraction.

The study also fits into a broader reassessment of PhoU’s role in bacterial physiology. Once regarded largely as a passive scaffold in the phosphate transporter complex, PhoU has now been shown in several organisms to act as a regulatory node, influencing stress tolerance, antibiotic persistence, and even secondary metabolism. In K. pneumoniae, the new results position it as a transcriptional upregulator of metE and phoA, thereby supporting the stress-response capacity of planktonic cells and, ultimately, the pathogen’s ability to survive antibiotic challenge. Because PhoU is conserved across many bacterial species but absent from humans, it represents an attractive target for future drug development, although the authors note that restoring either downstream gene only partially rescues the persister defect—implying that PhoU’s influence extends beyond the two pathways characterized so far.

Limitations remain, as with any laboratory study. The work was performed in a single reference strain under defined culture conditions, and persister frequencies can vary enormously across clinical isolates and infection environments. The team also relied on a limited set of antibiotics, and it is not yet known whether PhoU governs tolerance to beta-lactams or other drug classes through the same pathway. Still, the convergence of genetic, metabolomic, and transcriptomic evidence gives the model considerable weight: by sustaining methionine synthesis and phosphate-linked stress responses, PhoU keeps a reservoir of K. pneumoniae cells poised to survive antibiotic treatment. As antibiotics continue to lose ground against multidrug-resistant Gram-negative pathogens, understanding the molecular choreography of persistence—and finding the proteins that choreograph it—may prove as important as discovering new drugs themselves. This study provides one more name for that choreography, and a promising one at that.

Subject of Research: The role of the phosphate transport protein PhoU in regulating antibiotic persister cell formation in Klebsiella pneumoniae.

Article Title: The phosphate specific transport system protein PhoU modulates persister cell formation of Klebsiella pneumoniae

Article References: Sun, Y., Xu, W., Chen, K., Hong, X., Sun, X., Ma, W., Wang, X., Cao, Q., Xue, Z., Zhou, B., Zhang, Y., Liu, Z., Cui, Z., Wang, D., Dong, Z., & Zhang, Y. (2026). The phosphate specific transport system protein PhoU modulates persister cell formation of Klebsiella pneumoniae. Molecular Genetics and Genomics, 301(1), Article 197. https://doi.org/10.1007/s00438-026-02509-w

Image Credits: AI Generated

DOI: 10.1007/s00438-026-02509-w

Keywords: Klebsiella pneumoniae, PhoU, persister cells, antibiotic tolerance, biofilm, metabolomics, CRISPR-Cas9, methionine synthesis, alkaline phosphatase, Pho regulon, antimicrobial resistance, Molecular Genetics and Genomics