25 research outputs found
Purification and immobilization of engineered glucose dehydrogenase: A new approach to producing gluconic acid from breadwaste
Background Platform chemicals are essential to industrial processes. Used as starting materials for the manufacture of diverse products, their cheap availability and efficient sourcing are an industrial requirement. Increasing concerns about the depletion of natural resources and growing environmental consciousness have led to a focus on the economics and ecological viability of bio-based platform chemical production. Contemporary approaches include the use of immobilized enzymes that can be harnessed to produce high-value chemicals from waste. Results In this study, an engineered glucose dehydrogenase (GDH) was optimized for gluconic acid (GA) production. Sulfolobus solfataricus GDH was expressed in Escherichia coli. The Km and Vmax values for recombinant GDH were calculated as 0.87 mM and 5.91 U/mg, respectively. Recombinant GDH was immobilized on a hierarchically porous silica support (MM-SBA-15) and its activity was compared with GDH immobilized on three commercially available supports. MM-SBA-15 showed significantly higher immobilization efficiency (> 98%) than the commercial supports. After 5 cycles, GDH activity was at least 14% greater than the remaining activity on commercial supports. Glucose in bread waste hydrolysate was converted to GA by free-state and immobilized GDH. After the 10th reuse cycle on MM-SBA-15, a 22% conversion yield was observed, generating 25 gGA/gGDH. The highest GA production efficiency was 47 gGA/gGDH using free-state GDH. Conclusions This study demonstrates the feasibility of enzymatically converting BWH to GA: immobilizing GDH on MM-SBA-15 renders the enzyme more stable and permits its multiple reuse
Cloning, expression, purification and characterization of lipase from Bacillus licheniformis, isolated from hot spring of Himachal Pradesh, India
Angiotensin II Delays The Extinction of Active Avoidance in Rats The Role of Transmitter Receptors
The extinction of active avoidance behaviour in rats following the intracerebroventricular (ICV) injection of different doses of angiotensin II (Ang II) was studied. The influence of antagonists of different neurotransmitter receptors on the effects of Ang II was also followed. Ang II induced a delay in the extinction in a dose-dependent fashion (U-shaped curve). When the animals were pretreated with different receptor blockers in doses which themselves had no action on the extinction of active avoidance behaviour, the action of Ang II on this paradigm was completely blockednbsp by saralasin, haloperidol, bicuculline, atropine, naloxonenbsp Phenoxybenzamine,nbsp propanolol and methysergide were ineffective. The data suggest that Ang II delays the extinction of active avoidance behaviour, and that angiotensin, dopamine, GABAa, opiate might be involved in this action
Brevibacillus themoruber: a promising microbial cell factory for exopolysaccharide production
Aims: This study aims to identify a high level exopolysaccharide (EPS)
producer thermophile that in turn could be used as a model organism to study
the biological mechanisms and whole genome organization of EPS-producing
thermophilic bacteria.
Methods and Results: Thermophilic isolates were screened, and then growth
and EPS production of the best producer Brevibacillus thermoruber strain 423
were investigated under different carbon and nitrogen sources, temperature,
pH and agitation rates. Rheological characterization revealed that the EPS
behaved like a typical Newtonian fluid and viscosity of the EPS solution
increased with increasing Ca2+ ion concentration. Chemical characterization by
TLC, GC-MS, FT-IR and NMR suggested a heteropolymer structure with
glucose as major monomer unit. High biocompatibility of pure EPS fractions
suggested their potential use in biomedical applications.
Conclusions: This study reports on the comprehensive description of
microbial production conditions as well as chemical, rheological and biological
characterization of the EPS produced by B. thermoruber strain 423. The
bioreactor cultures were found to reach two times higher yields and three
times higher productivities when compared with literature.
Significance and Impact of the Study: Brevibacillus thermoruber strain 423
combined the advantages of its nonpathogenicity with the advantages of fast
productivity and hence proved to be a very promising model organism and
cell factory for microbial EPS production