Burn Wound Healing Abilities of a Uronic Acid Containing Exopolysaccharide Produced by the Marine Bacterium Halomonas malpeensis YU-PRIM-29 T.

Bacterial exopolysaccharides (EPS) are an emerging class of biopolymers with extensive applications in different fields due to their versatile physico-chemical and biological properties. The role of EPS in healing of different wound types is gaining interest in the tissue engineering sector. Burn is one of the devitalizing injuries that causes greater physical harm and can be fatal. Appropriate treatment modalities have to be followed for faster healing outcomes and to minimize the risk. In this study, a bacterial EPS (EPS-H29) from the marine bacterium Halomonas malpeensis YU-PRIM-29 T was used to treat the burn wound in vivo. The biochemical and structural characterizations of EPS-H29 were carried out using standard methods. In addition, FE-SEM, conformational, rheological, and HP-GPC analyses were carried out. In vitro biocompatibility of EPS-H29 was studied in human dermal fibroblasts (HDFs) and keratinocytes (HaCaT). Scratch assay was used to study the wound healing in vitro. For in vivo evaluation, burn wound (second-degree) was created on Wistar albino rats and treated with EPS-H29 along with appropriate control groups. The total sugar and protein contents of EPS-H29 were 72.0 ± 1.4% and 4.0 ± 0.5%, respectively, with a molecular weight of 5.2 × 105 Da. The lyophilized samples exhibited porous surface features, and in solution, it showed triple helical conformation and shear thickening behavior. In vitro cell-based assays showed biocompatibility of EPS-H29 up to 200 µg/mL concentration. At a concentration up to 50 µg/mL, EPS-H29 promoted cell proliferation. Significant increase in the HDF cell migration was evident with EPS-H29 (15 µg/mL) treatment in vitro and induced significantly higher (p ≤ 0.0001) closure of the scratch area (90.3 ± 1.1%), compared to the control (84.3 ± 1.3%) at 24 h. Enhanced expression of Ki-67 was associated with the cell proliferative activities of EPS-H29. The animals treated with EPS-H29 showed improved healing of burn wounds with significantly higher wound contraction rate (80.6 ± 9.4%) compared to the positive control (54.6 ± 8.0%) and untreated group (49.2 ± 3.7%) with histopathological evidence of epidermal tissue formation at 15 days of treatment. These results demonstrate the biocompatibility and burn wound healing capability of EPS-H29 and its potential as an effective topical agent for the burn wound care.

Differential expression of urease genes and ureolytic activity of uropathogenic Escherichia coli and Pseudomonas aeruginosa isolates in different nutritional conditions.

Uropathogens have adaptation strategies to survive in the host urinary tract by efficiently utilizing and tolerating the urinary metabolites. Many uropathogens harbour the enzyme urease for the breakdown of urea and the enzymatic breakdown of urea increases the pH and facilitate the struvite crystallization. In this study, the differential urease activity of uropathogenic Escherichia coli and Pseudomonas aeruginosa strains was investigated under different nutritional conditions. The experiments included measurement of growth, pH, urease activity, NH4-N generation and urease gene (ureC) expression among the bacterial strains under different conditions. Further, the implications of urea breakdown on the struvite crystallization in vitro and biofilm formation were also assessed. The study included urease positive isolates and for comparison urease negative isolates were included. Compared to the urease negative strains the urease positive strains formed higher biofilms and motility. The urease positive P. aeruginosa showed significantly higher (p < 0.01) pH and urease activity (A557-A630) compared to E. coli under experimental conditions. Further, supplementation of glucose to the growth media significantly increased the urease activity in P. aeruginosa and in contrast, it was significantly lower in E. coli. The expression profile of urease gene (ureC) was significantly higher (p < 0.001) in P. aeruginosa compared to E. coli and was consistent with the biochemical results of the urease activity under the nutritional conditions. The differential urease activity under two nutritional conditions influenced the biogenic struvite crystallization. It correlated with the urease activity showing higher crystallization rate in P. aeruginosa compared to E. coli. The results highlight the differential urease activity in two common uropathogens under different nutritional conditions that may have significant role on the regulation of virulence, pathogenicity and in the kidney stone disease.