Effects of shear stress and mass transfer on chitinase production by Paenibacillus sp. CHE-N1

Enhanced production of N-acetyl-glucosaminidase by marine Aeromonas caviae CHZ306 in bioreactor

N-Acetyl-glucosaminidases (GlcNAcases) are exoenzymes found in a wide range of living organisms, which have gained great attention in the treatment of disorders related to diabetes, Alzheimer's, Tay-Sachs', and Sandhoff's diseases; the control of phytopathogens; and the synthesis of bioactive GlcNAc-containing products. Aiming at future industrial applications, in this study, GlcNAcase production by marine Aeromonas caviae CHZ306 was enhanced first in shake flasks in terms of medium composition and then in bench-scale stirred-tank bioreactor in terms of physicochemical conditions. Stoichiometric balance between the bioavailability of carbon and nitrogen in the formulated culture medium, as well as the use of additional carbon and nitrogen sources, played a central role in improving the bioprocess, considerably increasing the enzyme productivity. The optimal cultivation medium was composed of colloidal α-chitin, corn steep liquor, peptone A, and mineral salts, in a 5.2 C:N ratio. Optimization of pH, temperature, colloidal α-chitin concentration, and kLa conditions further increased GlcNAcase productivity. Under optimized conditions in bioreactor (i.e., 34 °C, pH 8 and kLa 55.2 h-1), GlcNAcase activity achieved 173.4 U.L-1 after 12 h of cultivation, and productivity no less than 14.45 U.L-1.h-1 corresponding to a 370-fold enhancement compared to basal conditions.

Influence of oxygen transfer on Pseudomonas putida effects on growth rate and biodesulfurization capacity

The growth rate and desulfurization capacity accumulated by the cells during the growth of Pseudomonas putida KTH2 under different oxygen transfer conditions in a stirred and sparged tank bioreactor have been studied. Hydrodynamic conditions were changed using different agitation conditions. During the culture, several magnitudes associated to growth, such as the specific growth rate, the dissolved oxygen concentration and the carbon source consumption have been measured. Experimental results indicate that cultures are influenced by the fluid dynamic conditions into the bioreactor. An increase in the stirrer speed from 400 to 700 rpm has a positive influence on the cell growth rate. Nevertheless, the increase of agitation from 700 to 2000 rpm hardly has any influence on the growth rate. The effect of fluid dynamics on the cells development of the biodesulfurization (BDS) capacity of the cells during growth is different. The activities of the intracellular enzymes involved in the 4S pathway change with dissolved oxygen concentration. The enzyme activities have been evaluated in cells at several growth time and different hydrodynamic conditions. An increase of the agitation from 100 to 300 rpm has a positive influence on the development of the overall BDS capacity of the cells during growth. This capacity shows a decrease for higher stirrer speeds and the activity of the enzymes monooxygenases DszC and DszA decreases dramatically. The highest value of the activity of DszB enzyme was obtained with cells cultured at 100 rpm, while this activity decreases when the stirrer speed was increased higher than this value.

Statistical optimization of green fluorescent protein production from Escherichia coli BL21(DE3)

An optimized cultivation condition is needed to maximize the functional green fluorescent protein (GFP) production. Six process variables (agitation rate, temperature, initial medium pH, concentration of inducer, time of induction, and inoculum density) were screened using the fractional factorial design. Three variables (agitation rate, temperature, and time of induction) exerted significant effects on functional GFP production in E. coli shake flask cultivation and were optimized subsequently using the Box-Behnken design. An agitation rate of 206 rpm at 31°C and induction of the protein expression when the cell density (OD(600nm)) reaches 1.04 could enhance the yield of functional GFP production from 0.025 g/L to 0.241 g/L, which is about ninefold higher than the unoptimized conditions. Unoptimized cultivation conditions resulted in protein aggregation and hence reduced the quantity of functional GFP. The model and regression equation based on the shake flask cultivation could be applied to a 2-L bioreactor for maximum functional GFP production.

Production of leucine amino peptidase in lab scale bioreactors using Streptomyces gedanensis

Studies were conducted on the production of leucine amino peptidase (LAP) by Streptomyces gedanensis to ascertain the performance of the process in shake flask, parallel fermenter and 5-L fermenter utilizing soy bean meal as the carbon source. Experiments were conducted to analyze the effects of aeration and agitation rate on cell growth and LAP production. The results unveiled that an agitation rate of 300 rpm, 50% dissolved oxygen (DO) upholding and 0.15 vvm strategies were the optimal for the enzyme production, yielding 22.72 ± 0.11 IU/mL LAP in parallel fermenter which was comparable to flask level (24.65 ± 0.12 IU/mL LAP) fermentation. Further scale-up, in 5-L fermenter showed 50% DO and 1 vvm aeration rate was the best, producing optimum and the production was 20.09 ± 0.06 IU/mL LAP. The information obtained could be useful to design a strategy to improve a large-scale bioreactor cultivation of cells and production of LAP.

Bioprocessing data for the production of marine enzymes

This review is a synopsis of different bioprocess engineering approaches adopted for the production of marine enzymes. Three major modes of operation: batch, fed-batch and continuous have been used for production of enzymes (such as protease, chitinase, agarase, peroxidase) mainly from marine bacteria and fungi on a laboratory bioreactor and pilot plant scales. Submerged, immobilized and solid-state processes in batch mode were widely employed. The fed-batch process was also applied in several bioprocesses. Continuous processes with suspended cells as well as with immobilized cells have been used. Investigations in shake flasks were conducted with the prospect of large-scale processing in reactors.

Production of chitinolytic enzymes by a strain (BM17) of Paenibacillus pabuli isolated from crab shells samples collected in the east sector of central Tyrrhenian Sea

Nineteen bacterial isolates were grown in shaken cultures in media containing chitin as carbon source and different additional nitrogen sources such as yeast nitrogen base (YNB), yeast extract (YE), corn steep liquor (CSL) and ammonium sulfate. Strain BM17 showed the highest activity (200 U/l) in medium containing Chitin (1%) and YNB (0.5%). Molecular analysis of the 16S rRNA gene showed that strain BM17 belongs to the species Paenibacillus pabuli (99.72% homology). The enzyme activity started after 12-24 h; exponential enzyme production was recorded from the 24th h and lasted till the 96th h of incubation when activity peaked to decrease thereafter. Medium optimisation was carried out by Response Surface Methodology (RSM) considering the effects of chitin, corn steep liquor and yeast extract. BM17 chitinolytic activity was induced by chitin but the increase of its concentration did not have significant effects on the enzyme activity. By contrast, the nitrogen source, particularly YE, strongly affected the enzyme production.