Journal of Bioprocessing & Biotechniques

We compared the viability, proliferation, and differentiation of human Mesenchymal Stromal Cells (MSC) after culture on poly(lactic-co-glycolic acid) (PLGA) and PLGA/chitosan (PLGA/CH) hybrid scaffolds. We applied conventional and emulsion electrospinning techniques, respectively, for the fabrication of the PLGA and PLGA/ CH scaffolds. Electrospinning under optimum conditions resulted in an average fiber diameter of 166 ± 33 nm for the PLGA/CH and 680 ± 175 nm for the PLGA scaffold. The difference between the tensile strength of the PLGA and PLGA/CH nanofibers was not significant, but PLGA/CH showed a significantly lower tensile modulus and elongation at break. However, it should be noted that the extensibility of the PLGA/CH was higher than that of the nanofibrous scaffolds of pure chitosan. As expected, a higher degree of hydrophilicity was seen with PLGA/ CH, as compared to PLGA alone. The biocompatibility of the PLGA and PLGA/CH scaffolds was compared using MTS assay as well as analysis by scanning electron microscopy and confocal microscopy. The results showed that both scaffold types supported the viability and proliferation of human MSC, with significantly higher rates on PLGA/ CH nanofibers. Nonetheless, an analysis of gene expression of MSC grown on either PLGA or PLGA/CH showed a similar differentiation pattern towards bone, nerve and adipose tissues.

Feather waste is highly accumulated recalcitrant and non-efficiently utilized protein wastage of poultry processing. Present study highlights a cheap eco-friendly approach towards its valorization into efficiently utilized form (feather hydrolysate (SHG10 FH)) through Bacillus licheniformis SHG10 within 48 hrs. A statistical-mathematical model (Plackett-Burman Design (PBD), Central Composite Design (CCD), Canonical Analysis (CA) and Steepest Rising Ridge (SRR)) was anticipated to optimize feather bioconversion. PBD addressed three key determinants out of eight tested factors imposing significant influence (P≤0.006) on soluble proteins productivity. Optimal levels of the key determinants, localized by CCD, CA and SRR, were 1.55% (w/v) feather, 0.45% (w/v) yeast extract and 10.8% (v/v) inoculum size in basal medium II to attain 402 mg/Liter soluble proteins and 104,000 μmole leucine/Liter NH2-free amino groups. SHG10 FH was rich in phenylalanine, tyrosine, methionine and histidine. MALDI-TOF-MS showed proteins spectrum of SHG10 FH ranged from 140 Da m/z. to 733 Da m/z. The composition of SHG10 FH along with the ecologically safe low cost effective approach involved in its preparation might underpin its great potential in several industries (e.g., amino acids, soluble proteins, cosmetics and animal feed livestock).

Currently, fermentation is the only available pathway for converting carbohydrates to ethanol and it is often time-consuming. The focus of the current research is to expedite ethanol production from carbohydrates using Saccharomyces cerevisiae. This study evaluated fermentation using a high-speed stirrer (ultraturrax) where glucose was the model carbohydrate. The reaction kinetics of fermentation was evaluated using 13C NMR spectroscopy. The effect of stirring speed on the kinetics of glucose fermentation was studied and two times enhancement in the rate of fermentation was observed using an ultraturrax (3.80 ± 0.40 × 10-5 s-1) compared to the incubation (1.90 ± 0.71 × 10-5 s-1) at 30°C. The acceleration of the fermentation was also observed using other carbohydrates such as sucrose and molasses. We report the effect of varying a few parameters such as: stirring speed, the effect of shelf-life of yeast, pH of the broth, and effect of activated carbon on the fermentation kinetics. The optimum pH range for the fermentation reaction was found to be 4-6.8. Yeast with a six-month shelf-life was found to slow down the fermentation reaction by 5.6 times relative to fresh yeast (up to one month). Our results indicate an efficient method for bioethanol production from carbohydrates.

Catalase (EC 1.11.1.6) is a metalloenzyme belonging to the class of oxidoreductases which catalyze the degradation of hydrogen peroxide into dioxygen and water. Catalase, an important enzyme in the world market has wide range of industrial applications. In one of the important application, it is used to degrade unused hydrogen peroxide from wastewater released after bleaching operations in the textile industry. The use of catalase enzyme in soluble form is not feasible because of many economical and technical limitations. Therefore, the use of immobilized whole cells of bacterium having intracellular catalase activity is advantageous due to their repeated use, but it suffers from a drawback of instability and leakage of cells after some time. In the present study, sodium alginate beads used to immobilize Bacillus sp. TE-5 cells was modified to increase their stability and tested for the degradation of H₂O₂ in batch and continuous mode. The effect of other critical factors like sodium alginate concentration, bacterial cell load, glutaraldehyde concentration and treatment time for hardening beads was investigated to test their suitability for long term repeated operations. Maximum catalase activity (15900 IU/g of cells) was achieved by using modified sodium alginate beads cross linked with glutaraldehyde (0.10%, w/v) with CaCl₂ treatment time of 18 hr. The reusability of beads in a batch mode was studied to test their potential for continuous operations and then these immobilized cells were further used in a packed bed reactor for the degradation of H₂O₂ in continuous mode. These results provide an indication that this method of gel entrapment followed by cross-linking could be an effective, stable and better alternative for degradation of H₂O₂ in continuous system.

The coccolithophorid alga Emiliania huxleyi produces micro-structured calcite particles, which are called coccoliths. Due to their unique and sophisticated structure, coccoliths are highly promising for different industrial applications, such as paper manufacturing, color and lacquer preparation. The mass production of coccoliths requires the evaluation of optimum cultivation conditions. This study investigates the impact of varying irradiance (10-1500 μmol m^-2 s^-1) on growth and chlorophyll a content of two calcifying strains CCMP371 and RCC1216 as well as on the non-calcifying strain RCC1217 (haploid form of RCC1217). The light kinetics contradicts the popular opinion, that E. huxleyi is an extraordinarily light tolerating alga in general. Photoinhibition was already observed at irradiance >500 μmol m^-2 s^-1 in the case of the calcifying strains. Furthermore, light requirements to grow at maximum growth rate, as well as thresholds towards photoinhibition were considerably different between calcifying and non-calcifying strains. The haplont required significantly higher irradiance to reach maximum μ_spec (>200 μmol m^-2 s^-1), while being much more tolerant to towards photoinhibition, which occurred not until 800 μmol m^-2 s^-1. Furthermore, a novel method was proposed to allow for the estimation of chlorophyll a content from flow cytometry data. By comprising an Advanced Fluorescence Ratio (AFLR), which considers culture heterogeneity, this method enables for simple chlorophyll a estimation also in older cultures of calcifying Emiliania huxleyi, which tend to build agglomerates.