In the soil around a leaking industrial battery, scientists have found a microscopic ally with a taste for one of chemistry’s most feared poisons. A fungus named Aspergillus welwitschiae LOT1, isolated from land contaminated by battery effluent in Nigeria, can strip cyanide—the molecule behind mining disasters, poisoned waterways and countless detective novels—out of water with startling efficiency. Under conditions tuned by researchers at the Federal University of Technology in Akure, the mould degraded up to 85 percent of the cyanide in its culture medium, and under its best-performing setup it removed a stunning 99.8 percent of a high-concentration cyanide load. The work, published in International Microbiology, is the first systematic evaluation of how this industrially hardened fungus copes with cyanide as an intact, living system rather than as a purified enzyme, and it suggests that the answer to some of the world’s ugliest wastewater problems may already be growing in the dirt.

The reason this matters begins with cyanide itself. The ion is a potent cytotoxin and neurotoxin whose chemistry is brutally elegant: it infiltrates the respiratory machinery of the cell, crippling the terminal step that hands electrons to oxygen, so that organisms effectively suffocate from within even in oxygen-rich surroundings. Industry releases it on an enormous scale. Gold and silver mining, electroplating and a host of manufacturing processes all generate cyanide-laden effluents that can accumulate in soil, water and air, threatening ecosystems, biodiversity and human health. Clearing it away conventionally means chemical treatment or incineration—approaches that are costly, energy-intensive and prone to spawning secondary pollutants of their own. Bioremediation, in which living microbes dismantle toxins into simpler or far less harmful compounds, has long promised a cheaper and greener alternative, but finding organisms that survive the punishing reality of industrial wastewater—extreme pH, elevated temperatures and poison concentrations lethal to most life—has been a slow and uneven quest.

Most cyanide-degradation research has centred on bacteria such as Serratia marcescens, Klebsiella species and Micromonospora, with only a handful of fungi, among them Aspergillus niger and Rhizopus oryzae, receiving serious attention. Yet fungi carry traits that make them unusually suited to hostile environments: they tolerate harsh pH, remain metabolically active at elevated temperatures and high pollutant concentrations, and deploy broad arsenals of intracellular and extracellular enzymes, including hydratases and sulfurtransferases, capable of both degrading and detoxifying cyanide. LOT1 first attracted interest when Olusola Lawal and colleagues characterized a thermotolerant, thermostable rhodanese from the strain, which had been recovered from battery-effluent-contaminated soil, and later demonstrated the purified enzyme’s cyanide-detoxifying potential in vitro. But enzyme assays capture only a fragment of what an organism can do. Whole cells integrate intracellular metabolism, cofactor regeneration, stress-response pathways and substrate-transport mechanisms—capabilities no isolated protein possesses—so the team set out to interrogate the intact fungus, one environmental parameter at a time.

The strain, banked as GenBank accession MW463418, was grown on potato dextrose media; spore suspensions of roughly 7.2 million spores per millilitre were cultivated for three days, and the harvested biomass was centrifuged, washed in phosphate buffer and introduced into a defined mineral medium containing glucose, ammonium sulfate and a cocktail of trace metal salts, spiked with potassium cyanide. Cyanide loss was quantified with the classic picric acid colorimetric assay, in which cyanide reacts with picrate at high temperature to form a red-coloured complex measured spectrophotometrically at 520 nanometres. The researchers varied one factor at a time—substrate concentration from 5 to 100 millimolar, pH from 2 to 12, temperature from 30 to 70 degrees Celsius, inoculum size, carbon and nitrogen sources, agitation rate and incubation period—while uninoculated controls, which showed no detectable cyanide loss, accompanied every experiment. All trials ran in triplicate, and statistical differences were resolved by analysis of variance followed by Tukey’s post-hoc test at stringent significance thresholds.

The results mapped a creature of extremes. Degradation rose with substrate concentration to a peak of 74.8 percent at 60 millimolar cyanide, and even at 100 millimolar—levels that would devastate most microbial communities—the fungus still removed more than 60 percent. Alkalinity proved the strongest lever: removal climbed steadily with pH and topped out near 80 percent at pH 12, even though fungal growth itself peaked at pH 10, a hint that degradation and growth are distinct physiological enterprises. Temperature told a story of tolerance as well: activity and biomass both peaked at 50 degrees Celsius, a thermophilic inclination rare among cyanide degraders, most of which favour mesophilic conditions between 20 and 40 degrees; beyond 50 degrees, efficiency fell away sharply, consistent with partial thermal inactivation of the enzymes involved. Inoculum size mattered too. One millilitre of seed culture delivered the best degradation at 64.8 percent, while larger doses backfired—plausibly by crowding the flasks, exhausting nutrients and depleting oxygen—and fungal biomass itself declined at the highest seeding rates. Agitation produced only modest, statistically fragile gains, topping out at 25.7 percent at 200 revolutions per minute even as growth favoured the calmest flasks.

Nutrition shaped the outcome as much as physics. Every carbon source tested sustained degradation, with the disaccharides sucrose and lactose, at 28.5 and 27.4 percent in that screening round, edging past the monosaccharides. The detail is telling: disaccharides must first be hydrolysed before they can feed metabolism, so their effective use is evidence of genuine enzymatic activity rather than passive binding of cyanide to dead biomass. Among nitrogen sources, ammonium sulfate produced the highest degradation, followed by casein, while sodium nitrate lagged behind. The most striking nutritional result emerged when the team paired cyanide with matching glucose concentrations: 40 millimolar cyanide plus 40 millimolar glucose drove degradation to between 83.9 and 85.2 percent, with biomass highest in the same treatment. Glucose here behaves as a co-metabolite, supplying the energy that fuels enzyme synthesis and microbial work—a synergy previously documented in Trichoderma species and in bacteria degrading thiocyanate, where too little glucose demonstrably throttled degradation.

The study’s most economically resonant finding, however, concerns what the fungus was fed. When refined sugars were replaced with agricultural wastes, degradation did not suffer; it improved. Corn stalk supported the highest removal, roughly 84 percent, followed by locust bean and wheat bran, with locust bean leading among the nitrogen-yielding residues, while wheat bran also produced the greatest fungal biomass and soybean the least. Crop residues are rich in minerals, proteins and fermentable sugars, and they cost essentially nothing—much of what is not composted is simply burned. The finding slots into a growing literature: Aspergillus awamori has been shown to remediate cyanide in the presence of fruit and vegetable wastes, and Fusarium oxysporum achieved up to 77 percent degradation when grown on sugar-beet waste. Converting leftover corn stalks into feedstock for toxic-water treatment is precisely the circular-economy pairing environmental engineers dream about—one waste stream neutralizing another, at pennies per tonne.

What, chemically, was happening inside those flasks? High-performance liquid chromatography supplied the answer. Samples were extracted with ethanol, concentrated and injected onto a C-18 column eluted with a methanol-water mobile phase at 0.8 millilitres per minute, with ultraviolet detection at 210 nanometres and compound identity confirmed by matching retention times to standards within two percent, then verified by co-injection. The chromatograms revealed formamide, ammonia and carbon dioxide—the chemical fingerprints of a hydrolytic detoxification pathway centred on cyanide hydratase. In this scheme, cyanide is hydrated to formamide; formamide is then hydrolysed to ammonia and formate; and formate is oxidized further to carbon dioxide. The released ammonia doubles as a nitrogen source for the fungus, helping explain the steady biomass gains recorded over a week of incubation. The authors are appropriately cautious about one confound: strongly alkaline conditions can hydrolyse cyanide abiotically, without any help from biology. But because inoculated cultures far outperformed uninoculated controls and produced characteristic metabolites, the biological contribution appears substantial. Cyanide hydratase itself has a distinguished pedigree, first identified in Stemphylium loti in 1972 and since found in Gloeocercospora sorghi, Fusarium lateritium and Fusarium solani.

Benchmarked against other organisms, LOT1’s performance is exceptional. Under optimized conditions it removed 3,243.9 milligrams of cyanide from an initial 3,250—99.8 percent—surpassing figures reported for Polyporus arcularis at 72.1 percent, Rhizopus oryzae at 90 percent and Stemphylium loti at 95.3 percent, and outpacing bacterial standbys such as Pseudomonas pseudoalcaligenes, Pseudomonas fluorescens and Pseudomonas putida, whose best efficiencies ranged from 60 to 80 percent under comparable loads. Bacillus consortia, Klebsiella oxytoca and even the alga Scenedesmus obliquus, at around 91 percent, trail behind. The kinetics are equally impressive. In a time-course experiment, degradation peaked within the first 24 hours, while biomass continued climbing for a full week—a pace that outstrips Trametes versicolor, which needs around 66 hours to reach its maximum, and most newly characterized fungal biomasses, which require roughly 48. Sustained degradation above 60 percent at cyanide concentrations approaching 100 millimolar places LOT1 among the most tolerant whole-cell systems described to date.

The researchers are candid about the limits. Their experiments were confined to batch cultures, enzyme activity was inferred from metabolites rather than confirmed with a purified cyanide hydratase, and the one-factor-at-a-time strategy, while ideal for building baseline data on a newly characterized organism, is a starting point rather than a complete map of its potential. The next steps, they argue, are molecular characterization of the degradation enzymes and pilot-scale, field-based trials against real effluents from mining and electroplating operations. Even so, the message is difficult to ignore. A fungus that thrives at pH 12, at 50 degrees Celsius, and in cyanide concentrations that would kill most organisms was not engineered in a laboratory. It was found, quietly surviving in soil poisoned by battery waste—evolution’s own cleanup crew, already on site, already doing the job, waiting to be noticed.