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Freshwater Sponges Found to Remove Copper, Lead, Cadmium, and Arsenic from Polluted Waters

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  Published in Science and Technology on Tuesday, December 23rd 2025 at 2:32 GMT by The Hans India

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Freshwater Sponges: Tiny Allies in the Fight Against Heavy‑Metal Pollution

A recent study has uncovered an unexpected but powerful ally in the battle against heavy‑metal contamination in freshwater ecosystems: the microbiome that lives inside freshwater sponges. According to a report by The Hans India, researchers have identified specific bacterial strains associated with the common freshwater sponge Spongilla lacustris that can absorb, transform, and effectively remove toxic metals such as copper, lead, cadmium, and arsenic from water. This discovery could pave the way for innovative, low‑cost bioremediation strategies that harness natural microbial processes to clean polluted rivers, lakes, and industrial effluents.

The Heavy‑Metal Problem in India’s Waterways

India’s rivers and freshwater bodies have long suffered from escalating metal pollution. Industrial activities, mining, agricultural runoff, and urban waste discharge are steadily increasing concentrations of heavy metals, which pose serious risks to aquatic life, human health, and the overall ecological balance. Conventional treatment methods—chemical precipitation, ion exchange, and membrane filtration—are often expensive and generate secondary waste streams. As a result, scientists are actively seeking sustainable, biological alternatives that can operate at ambient temperatures, with minimal energy input and reduced chemical use.

Sponges as Natural Filters

Sponges have been celebrated for their unique feeding strategy: they continuously filter large volumes of water through their porous bodies, capturing microorganisms and detritus. In marine systems, sponge microbiomes have been shown to play crucial roles in nutrient cycling and disease resistance. However, freshwater sponges have received far less attention. Spongilla lacustris, the dominant freshwater sponge in many South Asian lakes, exhibits a remarkable capacity to thrive in polluted waters, hinting at an innate resistance to contaminants.

The new study—conducted by a team from the National Institute of Oceanography and the Indian Institute of Technology Kharagpur—delved into the microbial communities that reside within S. lacustris. Using high‑throughput DNA sequencing and culture‑based assays, the researchers isolated dozens of bacterial strains from sponge tissues and tested their metal‑tolerance and removal capabilities in controlled laboratory conditions.

Key Findings

1. High Metal Accumulation: Several isolates, particularly Pseudomonas sp. and Sphingomonas sp., accumulated up to 90 % of copper and 75 % of lead from spiked solutions within 48 hours. One Bacillus strain demonstrated the ability to reduce cadmium concentrations by 60 % via biomineralization.

2. Mechanisms of Metal Binding: The bacteria produce exopolysaccharides (EPS) that act as natural chelators, binding metal ions and preventing them from interacting with aquatic organisms. In addition, some strains secrete siderophores—iron‑chelating molecules—that inadvertently bind other metals, offering a dual protective effect.

3. Synergistic Microbial Consortia: When the isolates were grown together in a mixed culture, metal removal efficiencies increased by up to 30 % compared to individual strains. This suggests that the sponge microbiome functions as a cooperative community, each member specializing in different aspects of metal sequestration or detoxification.

4. Genetic Insights: Whole‑genome sequencing of the most potent strains revealed genes encoding metal‑resistance transporters, efflux pumps, and metal‑binding proteins. These genetic markers could guide future engineering efforts to enhance bioremediation capacity.

From Laboratory to Riverbank

The researchers are optimistic that the sponge‑derived microbes can be incorporated into practical water‑treatment systems. A pilot experiment involved embedding a small quantity of Pseudomonas sp. into a constructed wetland designed to mimic the sponge’s natural filtering environment. After three weeks, the wetland reduced copper and lead levels by 70 % in the inflow water.

Moreover, the study points out that S. lacustris itself can be cultivated at scale. The sponge’s robust growth in eutrophic conditions and its ability to tolerate high metal concentrations make it an excellent candidate for bioaugmentation. By reintroducing these sponges into polluted water bodies, it may be possible to create living “bio‑filters” that continuously clean the water as part of the ecosystem’s own natural processes.

Broader Implications

While the focus of the study is on freshwater sponges, the findings have broader implications for environmental microbiology and public policy. The concept of harnessing naturally occurring microbial communities for pollution mitigation aligns with the principles of circular economy and green chemistry. Furthermore, the research underscores the importance of preserving biodiversity—especially often‑overlooked organisms like freshwater sponges—as reservoirs of biotechnological potential.

The article also references complementary research published in Science Advances, where marine sponge microbiomes were shown to break down organophosphate pesticides, and Nature Communications, which highlighted Chitinophaga bacteria’s capacity to degrade plastic polymers. These examples collectively demonstrate that sponges, both marine and freshwater, are living laboratories of microbial innovation.

Looking Ahead

The next phase of the research involves scaling up the microbial consortia to pilot‑plant and field trials, assessing long‑term stability, potential ecological impacts, and cost‑effectiveness. Collaborations with environmental agencies in the Indian states of Karnataka and Tamil Nadu are already underway, with the aim of deploying sponge‑based bioreactors in municipal wastewater treatment facilities.

In conclusion, the discovery that freshwater sponge‑associated microbes can effectively tackle heavy‑metal pollution offers a promising, eco‑friendly solution to one of the most pressing environmental challenges of our time. By turning the natural filtering power of sponges into a tool for water purification, scientists are turning a humble, often‑neglected organism into a frontline defender of aquatic health.