Excellent laundry detergent compatibility and high dehairing ability of the Bacillus pumilus CBS alkaline proteinase (SAPB)

The newly Tunisian soil-isolated bacterium, producing the alkaline proteinase termed SAPB that was already purified and characterized [1], was assigned as Bacillus pumilus CBS strain on the basis of biochemical properties and 16S rRNA gene sequencing. The maximum protease activity recorded after 24 h of incubation in an optimized medium at 37°C was 6,500 U/mL in shaking flask culture and 25,000 U/mL in fermentor. SAPB showed excellent stability and compatibility in laundry detergent retaining more than 98% of its initial activity after pre-incubation for 1 h at 40°C with Det, followed by OMO (97%), Dinol (94%), and Dixan (93%). Examination of various stained cloth pieces exhibited a remarkable efficiency in the removal of blood and chocolate stains. More interestingly, SAPB demonstrated powerful dehairing capabilities of hair removal from skin with minimal damage on the collagen and a nearly complete feather-degradation. Likewise, Bacillus pumilus CBS effectively degraded feather-meal (98.5%), chicken feather (92%), goat hair (80%), and bovine hair (68%) whereas sheep wool under went less degradation. Keratin-degradation resulted in sulfhdryl group formation (0.95∼3.91 μM).     

Triangular gold nanoparticles modify shell characteristics and increase antioxidant enzyme activities in the clam Ruditapes decussatus

Context: Nanoparticles may cause adverse environmental effects but there is limited information on their interactions with marine organisms.

Objective: Our aim was to examine the effects of triangular gold nanoparticles (Tr-Au NPs) on the clam, Ruditapes decussatus.

Materials and methods: Clams were exposed to Tr-Au1?=?5?µg/L and Tr-Au2?=?10?µg/L for 2 and 7?days. Effects on shell structure were investigated. Superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, protein carbonyl levels and malondialdehyde content were used to assess biochemical status.

Results: Transmission electron microscopy (TEM) and electron dispersive X-ray microanalysis (EDX) showed that Tr-Au NPs modified shell structure and morphology. Tr-Au NPs size increased forming aggregate particles. Tr-Au NPs increased SOD, CAT and GST activities in gill and digestive gland in a concentration- and time-dependent manner indicating defence against oxidative stress. Enhanced lipid peroxidation and protein carbonyl levels confirmed oxidative stress.

Conclusion: Tr-Au NPs cause oxidative stress and affect shell structure of clams. These findings may have relevance to other marine species.     

Production of lysine by using immobilized livingCorynebacterium sp cells

Summary Lysine production by immobilizedCorynebacterium sp cells in alginate gel beads was investigated in flasks. ImmobilizedCorynebacterium sp cells exhibited a slightly greater lysine production than free cells and accumulated 60 g/l of L-lysine at maximum, when cultured for 120h in a medium containing 200g/l glucose as carbon source. Several factors, such as inoculum size, incubation time and alginate gel concentration were examined in order to improve lysine production by immobilized growing cells.