A new uranium bioremediation approach using radio-tolerant Deinococcus radiodurans biofilm

Deinococcus radiodurans is the most radiation-tolerant organism ever known. It has gained importance in recent years as apotential candidate for bioremediation of heavy metals, especially the radioactive type. This study investigates the efficiency of a recombinant D. radiodurans (DR1-bf?) strain with an ability to form biofilm for uranium remediation. Themodified Arsenazo III dye method was used to estimate the uranium concentration. Uranyl nitrate aqueous solution wasgenerated during the operation of nuclear fuel reprocessing. The D. radiodurans biofilm (DR1-bf?) grown in the presenceof 20 mM Ca2? showed remarkable ability of uranyl ion removal. DR1-bf? (?Ca2?) biofilm removed *75±2% of1000 mg/L uranium within 30 min post-treatment from uranyl nitrate aqueous solution. Uranium removal rate was alsofound to be directly proportional to biofilm age. This study discusses the ability of D. radiodurans biofilm in uraniumremoval.

Microbiota of spent nuclear fuel pool water with emphasis on their biofilm forming ability on stainless steel (SS-304L)

Spent nuclear fuel (SNF) pool is an essential unit of a nuclear power plant infrastructure, where radioactive fuel rods arekept for cooling and shielding, before reprocessing. This study explored the presence of bacteria in SNF pool water withemphasis on their capability to form biofilms on pool wall cladding material stainless steel (SS-304L). Bacteria wereisolated from SNF pool water and were characterized using 16S rRNA gene sequencing. The six bacterial isolates (Bacillussubtilis, Staphylococcus sps., S. arlettae, S. epidermidis, S. auricularis and Chryseobacterium gleum) can grow and formbiofilms at very low nutrient condition as well as in chronic radioactivity. The bacterial isolates formed biofilm on SS-304Land glass. However, the biofilm parameters assessed by CLSM microscopy showed that the strains preferred SS-304Lsurface for biofilm formation. On SS-304L, the maximum biomass (0.45 lm3/lm2) was formed by S. arlettae whencompared to maximum biomass (0.054 lm3/lm2) by Staphylococcus sp., on glass. Maximum biofilm thickness on SS304L was observed by Staphylococcus sp. (8.81 lm) when compared to that of S. epidermidis (4.16 lm) on the glasssurface. The biofilm formation on SS-304L surface suggests the possible risk of microbial-induced corrosion of SNF poolcladding material. This study highlights the need for mandatory monitoring of microbial biofilm formation in an extremeenvironment such as SNF pool.