A study of cell disruption of Candida mogii by glass bead mill for the recovery of xylose reductase

Impact of Sample Storage on the NMR Fecal Water Metabolome

The study of the fecal metabolome is an important area of research to better understand the human gut microbiome and its impact on human health and diseases. However, there is a lack of work in examining the impact of storage and processing conditions on the metabolite levels of fecal water. Furthermore, there is no universal protocol used for the storage of fecal samples and preparation of fecal water. The objective of the current study was to examine the impact of different storage conditions on fecal samples prior to metabolite extraction. Fecal samples obtained from nine healthy individuals were processed under different conditions: (1) fresh samples prepared immediately after collection, (2) fecal samples stored at 4 °C for 24 h prior to processing, and (3) fecal samples stored at -80 °C for 24 h prior to processing. All samples were analyzed using NMR spectroscopy, multivariate statistical analysis, and repeated measures ANOVA. Samples which were frozen at -80 °C prior to extraction of the metabolites exhibited an increase in the number of metabolites including branched-chain amino acids, aromatic amino acids, and tricarboxylic acid cycle intermediates. Storage of fecal samples at 4 °C ensured higher fidelity to freshly processed samples leading to the recommendation that fecal samples should not be frozen prior to extraction of fecal water. Furthermore, the work highlights the need to standardize sample storage of fecal samples to allow for the accurate study of the fecal metabolome.

Optimization of intracellular product release from Neisseria denitrificans using microfluidizer

Disruption of Neisseria denitrificans cells by microfluidizer was optimized using a factorial experiments design. The pH, pretreatment time, cell concentration, NaCl, ethylenediamine tetraacetic acid (EDTA) and Triton X-100 concentrations showed significant impact on disruption process and the process was optimized using central composite design and response surface methodology (RSM). Investigation revealed optimum conditions: 90 min pretreatment at pH 9.0 containing 110 g L(-1) cells (dry cell weight), 50 mM NaCl, 10 mM EDTA, and 0.2% Triton X-100. At optimized conditions, the disruption rate increased twofold, up to 5.62 ± 0.27 × 10(-3) MPa(-a); meanwhile, yield of intracellular content was increased by 26%, with 1 g of cells resulting in 113.2 ± 8.2 mg proteins, 12.1 ± 0.7 mg nucleic acids, 21.0 ± 1.2 mg polysaccharides, 0.99 ± 0.08 kU glucose-6-phosphate dehydrogenase (G6PD), and 10,100 ± 110 kU restriction endonuclease NdeI endonuclease. Particle size distribution analysis revealed nearly twofold larger cell lysate particles with diameter of 120 nm. For optimal release of intracellular content, 9200 J/g of energy was needed (95% confidence), yielding 6900 J/g energy savings. Model equations generated from RSM on cell disruption of N. denitrificans were found adequate to determine significant factors and its interaction. The results showed that optimized combination of known pretreatment and disruption methods could considerably improve cell disruption efficiency.

Investigations on ideal mode of cell disruption in extremely halophilic Actinopolyspora halophila (MTCC 263) for efficient release of glycine betaine and trehalose

Actinopolyspora halophila produces glycine betaine and trehalose intracellularly in considerable quantities. These biomolecules are commercially important as they have applications in food, pharmaceuticals, and agricultural sector. Development of an efficient cell disruption technique is an important step for the release of these biomolecules. In this study, various cell disruption methods such as chemical, enzymatic, physico-mechanical and physical methods were evaluated. Cell disruption by osmotic shock was found to be the best suited method for A. halophila which also has a potential to be industrially scaled up. Cell bursting pressure that is generated during osmotic shock in A. halophila was computed using Morse equation and was found to be π = 238.37 ± 29.54 atm or 2.35 ± 0.29 kPa. In addition, it was found that osmotic shock followed a first order release rate kinetics in A. halophila. The findings can be used for commercially important biomolecules from other halophilic and/or halotolerant microbes.

Effects of cell lysis treatments on the yield of coenzyme Q10 following Agrobacterium tumefaciens fermentation

The yield of CoQ₁₀, an intracellular product extracted from Agrobacterium tumefaciens cells is dependent on the effectiveness of cell lysis post fermentation. Various cell lysis approaches are investigated, including ultrasound, repetitive freezing/thawing, grinding and acid-heat treatment. The acid-heat combination using hydrochloric acid is found the most effective in releasing CoQ₁₀, followed by lactic, sulfuric, phosphoric and oxalic acids. The most significant processing parameters, namely the ratio of acid solution volume and bacteria weight (A/B ratio), incubation temperature and reaction time, are optimized by using the central composite design with a quadratic regression model built by response surface methodology. The highest CoQ₁₀ yield at 1.518 mg/g dry cell is attained using hydrochloric acid (3 mol/L) under optimal A/B ratio, temperature and time at 10.8 mL/g, 84.2 °C and 35.3 min, respectively.