Abdul Wahab Khan
Panaji
A bacterium living on jellyfish found off the Goa coast has emerged as a promising source of a biodegradable polymer after researchers isolated it from Chrysaora and demonstrated its ability to rapidly produce exopolysaccharide (EPS), a class of biopolymers with potential applications ranging from food and cosmetics to pharmaceuticals and environmental remediation.
The study found that optimising the bacterium’s growth conditions increased EPS production from 3.26 to 4.26 grammes per litre, with the higher yield achieved in just 36 hours.
The researchers undertook the work because the microbial communities associated with jellyfish remain poorly explored, particularly along the Indian coast.
Goa’s coastal waters experience changing ecological conditions caused by monsoon-driven estuarine inputs and salinity variations, while Chrysaora is commonly found in these waters. The scientists said these conditions and the jellyfish’s specialised microhabitats could harbour bacteria with novel EPS-producing capabilities.
For the investigation, Chrysaora specimens were collected using a scoop net near the Mandovi estuary at a water depth of 10 metres. The jellyfish were transported to the laboratory in aerated tanks containing pre-filtered seawater. Researchers washed the specimens three times to remove loosely attached microorganisms before sampling mucus, oral-arm tissue and the gastric cavity. Samples were cultured on Zobell Marine Agar at 30°C for 48 hours, producing 11 morphologically distinct bacterial isolates.
The isolates were screened for EPS using the phenol-sulfuric acid assay. The strongest producer, JAB08, yielded 3.26 g/litre, considerably higher than JAB09 and JAB04. The strain was then confirmed as an EPS producer using Congo red agar. Molecular identification involved 16S rRNA gene amplification, Sanger sequencing and comparison with the EzTaxon database. JAB08 showed 99.7 per cent similarity to Brevibacterium and was designated Brevibacterium sp. JAB08, with its sequence deposited in GenBank under accession PX323525.
The researchers next examined bacterial growth over 96 hours and measured EPS production at regular intervals. They found a 12-hour lag phase followed by exponential growth, while EPS production began at 12 hours and increased substantially during the stationary phase. The study noted that the pattern indicates EPS synthesis is likely a “stress-adaptive response rather than a primary metabolic process associated with growth”.
A three-factor, three-level Box-Behnken Design combined with response surface methodology was then used to optimise sucrose concentration, inoculum size and incubation time. The optimum was 3 per cent sucrose, 2 per cent inoculum and 36 hours, producing an observed crude EPS yield of 4.26 g/litre against a model prediction of 4.22 g/litre.
The statistical model explained 95.04 per cent of the variation in EPS yield, although the researchers cautioned that its lower predicted R² and significant lack of fit showed limitations in predictive performance.
Structural examination provided further clues about the material. FTIR analysis indicated a polysaccharide rich in hydroxyl groups and glycosidic linkages, with the researchers describing it as predominantly neutral and containing β-glycosidic features. SEM examination showed porous structures, ridges, grooves and interconnected fibrillar networks. The paper said these observations provide “preliminary structural insights into the crude polysaccharide fraction”.
The study, ‘Screening and optimisation of crude exopolysaccharide production by marine Brevibacterium sp. JAB08 isolated from the jellyfish Chrysaora sp. from the coastal waters of Goa’, was published in the journal Antonie van Leeuwenhoek in 2026.
It was authored by Balaji Vaishnavi, R Amal, Biraja Kumar Sahu and SV Sandhya.
Sandhya, Sahu and Vaishnavi are associated with the CSIR-National Institute of Oceanography, Dona Paula, Goa, while Vaishnavi is also affiliated with the School of Chemical and Biotechnology, SASTRA University, Tamil Nadu, and Amal with the ICMR Regional Medical Research Centre, Sri Vijaya Puram.
The researchers believe the EPS may help the bacterium survive stressful marine conditions and potentially contribute to biofilm formation and protection within the jellyfish’s microbial community. Its porous and hydrophilic characteristics could eventually make it relevant to moisture-retention materials, environmental remediation and other biotechnology applications. However, the scientists stressed that these possibilities remain to be tested.
Importantly, the study has not claimed that a commercial product has already been developed. The EPS was examined in crude, ethanol-precipitated form without purification. The researchers said future work must determine its monosaccharide composition, molecular weight, detailed physicochemical properties and application-specific performance.
They reckoned that jellyfish-associated bacteria represent a largely unexplored source of marine biopolymers and identified JAB08 as a “promising and time-efficient source of crude exopolysaccharide”.
