Effect of agitation and aeration on the production of nitrile hydratase by Rhodococcus erythropolis MTCC 1526 in a stirred tank reactor

Production of extracellular agarase from Priestia megaterium AT7 and evaluation on marine algae hydrolysis

Agar is a common component biosynthesized from various marine algae species that is widely applied in various fields including food and pharmaceutical industries. However, the structural composition of agar is highly resisted against chemical and biological hydrolysis. Therefore, tremendous research is exploring various pretreatment strategies to break down the intrinsic chemical structural of agar linkage (i.e. neutral agarose and highly sulfated agaropectin) prior for its industrial potential usage. In this research work, a novel agar degrading bacterium was screened and isolated from agriculture soils. Molecular identification using nucleotide sequence of 16 s rRNA region comparison has indicated that the isolate belonged to Priestia genus, and was identified as Priestia megaterium AT7. The maximum enzyme activity was 52.85 ± 1.76 U/mL after 96 h of culture with 5% inoculum size and agitation speed of 180 rpm. Results indicated that the optimal condition for the production of agarose was achieved at pH 7 at 50 °C. The effects of metal ions (e.g. Ca2+, Co2+, Cu2+, Mn2+, Mg2+, Zn2+ and Fe2+) and organic solvents (e.g. acetone, ethanol, methanol, hexane and isopropanol) on enzyme activity were also evaluated. Marine algae hydrolysis evaluation at concentration of 0.1% indicated the enzyme produced reducing sugar of 683.94 ± 26.93 µg/g after 24 h of treatment. It was also found that the highest antioxidant activities obtained after 20 h of treatment was able to achieve 81.76 ± 3.90% at marine algae concentration of 0.1%. The findings obtained from this research work shows the promising application of extracellular agarase to saccharify marine algae for the recovery of value-added bioproducts.

Enhanced vanillin production from eugenol by Bacillus cereus NCIM-5727

Biovanillin production by a wild strain of Bacillus cereus NCIM-5727 is studied using eugenol as the precursor aiming to achieve maximum vanillin productivity. Based on shake flask optimization, molar yield and global volumetric productivity of vanillin reached up to 71.2% (6.6 gL^-1) and 0.18 g(Lh)^-1, respectively, at 36 h by resting cells of B. cereus NCIM-5727 at the optimum cell concentration of 3 gL^-1 using eugenol concentration of 10 gL^-1 at 37 ºC, buffer pH 7.0, buffer volume 10%, and shaking speed 180 rpm. Furthermore, small-scale optimization in a bioreactor at the controlled aeration rate of 0.5 Lmin^-1, agitation rate of 210 rpm, and pH 7.0 enhanced the global volumetric productivity of vanillin up to 0.28 g(Lh)^-1 at 25 h of bioconversion. The highest vanillin molar yield (75.2%) is reported using resting cells of B. cereus NCIM-5727 upon eugenol biotransformation and found stable for 10 h.

Glycerol as a substrate for actinobacteria of biotechnological interest: Advantages and perspectives in circular economy systems

Actinobacteria represent a ubiquitous group of microorganisms widely distributed in ecosystems. They have diverse physiological and metabolic properties, including the production of extracellular enzymes and a variety of secondary bioactive metabolites, such as antibiotics, immunosuppressants, and other compounds of industrial interest. Therefore, actinobacteria have been used for biotechnological purposes for more than three decades. The development of a biotechnological process requires the evaluation of its cost/benefit ratio, including the search for economic and efficient substrates for microorganisms development. Biodiesel is a clean, renewable, quality and economically viable source of energy, which also contributes to the conservation of the environment. Crude glycerol is the main by-product of biodiesel production and has many properties, so it has a commercial value that can be used to finance the biofuel production process. Actinobacteria can use glycerol as a source of carbon and energy, either pure o crude. A circular economy system aims to eliminate waste and pollution, keep products and materials in use, and regenerate natural systems. Although these principles are not yet met, some approaches are being made in this direction; the transformation of crude glycerol by actinobacteria is a process with great potential to be scaled on an industrial level. This review discusses the reports on glycerol as a promising source of carbon and energy for obtaining biomass and high-added value products by actinobacteria. Also, the factors influencing the biomass and secondary metabolites production in bioreactors are analyzed, and the tools available to overcome those that generate the main problems are discussed.

Method development for the clearance study of the Pluronic F-68 nonionic surfactant used in the upstream process of monoclonal antibody production

Pluronic F-68 is a nonionic surfactant, which is often used in the upstream process of biopharmaceutical production. However, the number of analytical methods developed for determination of Pluronic F-68 in the in-process and drug substance samples of biological drug production process is quite low. The lack of chromophore groups on the molecule and the interference caused by the high protein content of the samples hamper analysis. In this paper the development and qualification of a mixed-mode (MM) HPLC method with charged aerosol detection is reported. The method enables the analysis of samples with up to 85 g/L protein concentration. The range of the method was set to 250-500 μg/mL, where it was found to be accurate (89-111 % recovery) and precise (0.8-3.2 % relative standard deviation). The high sensitivity of the method indicates that even lower concentration range can be feasible. The novel method successfully demonstrates Pluronic F-68 clearance during the downstream process of the monoclonal antibody production.

Production of lipopeptide biosurfactant in batch and fed-batch Streptomyces sp. PBD-410L cultures growing on palm oil

The present study focused on lipopeptide biosurfactant production by Streptomyces sp. PBD-410L in batch and fed-batch fermentation in a 3-L stirred-tank reactor (STR) using palm oil as a sole carbon source. In batch cultivation, the impact of bioprocessing parameters, namely aeration rate and agitation speed, was studied to improve biomass growth and lipopeptide biosurfactant production. The maximum oil spreading technique (OST) result (45 mm) which corresponds to 3.74 g/L of biosurfactant produced, was attained when the culture was agitated at 200 rpm and aeration rate of 0.5 vvm. The best aeration rate and agitation speed obtained from the batch cultivation was adopted in the fed-batch cultivation using DO-stat feeding strategy to further improve the lipopeptide biosurfactant production. The lipopeptide biosurfactant production was enhanced from 3.74 to 5.32 g/L via fed-batch fermentation mode at an initial feed rate of 0.6 mL/h compared to that in batch cultivation. This is the first report on the employment of fed-batch cultivation on the production of biosurfactant by genus Streptomyces.

Enhancement of bioplastic polyhydroxybutyrate P(3HB) production from glucose by newly engineered strain Cupriavidus necator NSDG-GG using response surface methodology

This study aimed to enhance production of polyhydroxybutyrate P(3HB) by a newly engineered strain of Cupriavidus necator NSDG-GG by applying response surface methodology (RSM). From initial experiment of one-factor-at-a-time (OFAT), glucose and urea were found to be the most significant substrates as carbon and nitrogen sources, respectively, for the production of P(3HB). OFAT experiment results showed that the maximum biomass, P(3HB) content, and P(3HB) concentration of 8.95 g/L, 76 wt%, and 6.80 g/L were achieved at 25 g/L glucose and 0.54 g/L urea with an agitation rate of 200 rpm at 30 °C after 48 h. In this study, RSM was applied to optimize the three key variables (glucose concentration, urea concentration, and agitation speed) at a time to obtain optimal conditions in a multivariable system. Fermentation experiments were conducted in shaking flask by cultivation of C. necator NSDG-GG using various glucose concentrations (10-50 g/L), urea concentrations (0.27-0.73 g/L), and agitation speeds (150-250 rpm). The interaction between the variables studied was analyzed by ANOVA analysis. The RSM results indicated that the optimum cultivation conditions were 37.70 g/L glucose, 0.73 g/L urea, and 200 rpm agitation speed. The validation experiments under optimum conditions produced the highest biomass of 12.84 g/L, P(3HB) content of 92.16 wt%, and P(3HB) concentration of 11.83 g/L. RSM was found to be an efficient method in enhancing the production of biomass, P(3HB) content, and P(3HB) concentration by 43, 21, and 74%, respectively.

Effects of Agitation, Aeration and Temperature on Production of a Novel Glycoprotein GP-1 by Streptomyces kanasenisi ZX01 and Scale-Up Based on Volumetric Oxygen Transfer Coefficient

The effects of temperature, agitation and aeration on glycoprotein GP-1 production by Streptomyces kanasenisi ZX01 in bench-scale fermentors were systematically investigated. The maximum final GP-1 production was achieved at an agitation speed of 200 rpm, aeration rate of 2.0 vvm and temperature of 30 °C. By using a dynamic gassing out method, the effects of agitation and aeration on volumetric oxygen transfer coefficient (k_La) were also studied. The values of volumetric oxygen transfer coefficient in the logarithmic phase increased with increase of agitation speed (from 14.53 to 32.82 h⁻¹) and aeration rate (from 13.21 to 22.43 h⁻¹). In addition, a successful scale-up from bench-scale to pilot-scale was performed based on volumetric oxygen transfer coefficient, resulting in final GP-1 production of 3.92, 4.03, 3.82 and 4.20 mg/L in 5 L, 15 L, 70 L and 500 L fermentors, respectively. These results indicated that constant volumetric oxygen transfer coefficient was appropriate for the scale-up of batch fermentation of glycoprotein GP-1 by Streptomyces kanasenisi ZX01, and this scale-up strategy successfully achieved 100-fold scale-up from bench-scale to pilot-scale fermentor.

Production of carotenoids and lipids by Rhodococcus opacus PD630 in batch and fed-batch culture

Production of carotenoids by Rhodococcus opacus PD630 is reported. A modified mineral salt medium formulated with glycerol as an inexpensive carbon source was used for the fermentation. Ammonium acetate was the nitrogen source. A dry cell mass concentration of nearly 5.4 g/L could be produced in shake flasks with a carotenoid concentration of 0.54 mg/L. In batch culture in a 5 L bioreactor, without pH control, the maximum dry biomass concentration was ~30 % lower than in shake flasks and the carotenoids concentration was 0.09 mg/L. Both the biomass concentration and the carotenoids concentration could be raised using a fed-batch operation with a feed mixture of ammonium acetate and acetic acid. With this strategy, the final biomass concentration was 8.2 g/L and the carotenoids concentration was 0.20 mg/L in a 10-day fermentation. A control of pH proved to be unnecessary for maximizing the production of carotenoids in this fermentation.