Arsenic biosorption using pretreated biomass of psychrotolerant Yersinia sp. strain SOM-12D3 isolated from Svalbard, Arctic

A Gram-negative, arsenite-resistant psychrotolerant bacterial strain, Yersinia sp. strain SOM-12D3, was isolated from a biofilm sample collected from a lake at Svalbard in the Arctic area. To our knowledge, this is the first study on the ability of acid-treated and untreated, non-living biomass of strain SOM-12D3 to absorb arsenic. We conducted batch experiments at pH 7, with an initial As(III) concentration of 6.5 ppm, at 30 °C with 80 min of contact time. The Langmuir isotherm model fitted the equilibrium data better than Freundlich, and the sorption kinetics of As(III) biosorption followed the pseudo-second-order rate equation well for both types of non-living biomass. The highest biosorption capacity of the acid-treated biomass obtained by the Langmuir model was 159 mg/g. Further, a high recovery efficiency of 96% for As(III) was achieved using 0.1 M HCl within four cycles, which indicated high adsorption/desorption. Fourier transformed infrared (FTIR) demonstrated the involvement of hydroxyl, amide, and amine groups in As(III) biosorption. Field emission scanning electron microscopy–energy dispersive analysis (FESEM-EDAX) indicated the different morphological changes occurring in the cell after acid treatment and arsenic biosorption. Our results highlight the potential of using acid-treated non-living biomass of the psychrotolerant bacterium, Yersinia sp. Strain SOM-12D3 as a new biosorbent to remove As(III) from contaminated waters

BMP treatment for improving tendon repair. Studies on rat and rabbit Achilles tendons

We wanted to improve tendon healing by adding a growth factor. Bone Morphogenetic Proteins (BMPs) are well known to stimulate bone healing and bone formation. The local environment is of major importance for cell differentiation after a BMP has been added. Cartilage Derived Morphogenetic Proteins (CDMPs) -1, -2 and -3 (BMP 14, 13 and 12 or GDF 5, 6 and 7) form a subgroup in the BMP-family and are closely related to OP-1 (BMP 7). CDMP implants have been shown to induce bone and cartilage as well as tendon and ligament-like tissue. Our hypothesis has therefore been that if a BMP were added in a tendon environment, a tendon-like tissue would be induced. We have developed models in rats and rabbits where the Achilles tendon is transsected. To influence tendon healing, different BMPs (OP-1, CDMP-1. -2 and -3) were added, either on a collagen carrier, or as a local injection into the tendon defect. The tendons were evaluated by histology and mechanical testing at different time-points after transection. The results show that also when the mechanical environment would favour the formation of a tendon-like tissue, OP-1 reduced tendon strength in aid of bone formation. In contrast, CDMP-1, -2 and -3 had a beneficial effect upon tendon healing in rats. More callus tissue was produced than in controls, and strength and stiffness were improved, although minor amounts of bone and cartilage were detected in the tendon callus. Cartilage and bone formation sometimes occur normally during Achilles tendon healing in rats. In the rabbit model, where the healing situation is more similar to the clinical situation, the positive result with CDMP-2 was repeated. Moreover, in rabbits no bone or cartilage was found. The results suggest that conservative treatment of Achilles tendon ruptures with injection of a CDMP in combination with early rehabilitation might afford a good alternative to surgical treatment