Selective extraction of acetic acid from the fermentation broth produced by Mannheimia succiniciproducens

Acetic acid is by-product from fermentation processes for producing succinic acid using Mannheimia succiniciproducens . To obtain pure succinic acid from the final fermentation broth, acetic acid was selectively removed based on the different extractability of succinic acid and acetic acid with pH using tri-n-octylamine (TOA) as extractant. When successive batch extractions were performed using 0.25 mol TOA kg(-1) dissolved in 1-octanol at pH 5, the mol ratio of succinic acid to acetic acid before extraction was 4.9 and the final ratio after the fourth batch was 9.4.     

Selective extraction of succinic acid from binary mixture of succinic acid and acetic acid

In production of succinic acid by fermentation, succinic acid and acetic acid are co-produced. To purify the succinic acid from binary-acid mixture of succinic acid and acetic acid, the tertiary amine-based extraction was used. In 1-octanol, the selectivity for succinic acid was proportional to the chain length of tertiary amine. But, the distribution of acids into organic phase was low in n-heptane. These results are due to the different degree of intramolecular hydrogen bonding of succinic acid and hydrophobicity of each acid.     

Isolation and classification of acetic acid bacteria from high percentage vinegar fermentations

Summary A method for growing acetic acid bacteria from high percentage submerged vinegar fermentations was established by overflowing soft agar, containing acetic acid, with fermenting reactor fluid. Mixed cultures were found in a submerged process that was working well (1), in a submerged process that had broken down (2), and in a vinegar generator (3). The strains differed in part from each other with respect to tolerance towards acetic acid, ethanol, pH and in other physiological criteria. All strains that were isolated from (1) and some from (3) were specialized for acetate media as they needed acetic acid and low pH values (2.1–3.8) in addition to yeast extract and glucose or ethanol. We suppose that they belonged to the acetic acid-producing strains active in the process. None of the strains derived from (2) was of this acetophilic type. All except one of the stains from (2) belonged to the species Acetobacter hansenii, the other cultures were of A. pasteurianus.     

Separation of type III collagen from type I collagen and pepsin by differential denaturation and renaturation.

Types I and III collagens were solubilized from fetal human skin by limited digestion with pepsin and precipitated by dialysis against 0.02 M Na₂HPO₄. Heat denaturation of the collagens in 2 M guanidine-HCl, pH 7.5, resulted in the precipitation of the contaminant pepsin which could be removed by centrifugation. Renaturation of the denatured collagens by dialysis against deionized water at 22° for 2 hours selectively precipitated the type III collagen fibrils. Type I collagen remained in solution. The simplicity and high recovery (77%) make this a suitable approach for the rapid estimation of type III collagen in small tissue samples.     

Assessment of viral inactivation during pH 3.3 pepsin digestion and caprylic acid treatment of antivenoms

Antivenoms are manufactured by the fractionation of animal plasma which may possibly be contaminated by infectious agents pathogenic to humans. This study was carried out to determine whether pre-existing antivenom production steps, as carried out by EgyVac in Egypt, may reduce viral risks. Two typical manufacturing steps were studied by performing down-scaled viral inactivation experiments: (a) a pH 3.3 pepsin digestion of diluted plasma at 30 degrees C for 1h, and (b) a caprylic acid treatment of a purified F(ab')2 fragment fraction at 18 degrees C for 1h. Three lipid-enveloped (LE) viruses [bovine viral diarrhoea virus (BVDV), pseudorabies virus (PRV), and vesicular stomatitis virus (VSV)] and one non-lipid-enveloped (NLE) virus [encephalomyocarditis virus (EMC)] were used as models. Kinetics of inactivation was determined by taking samples at 3 time-points during the treatments. The pH 3.3 pepsin digestion resulted in complete clearance of PRV (>7.0 log(10)) and in almost complete reduction of VSV (>4.5 but < or =6.4 log(10)), and in a limited inactivation of BVDV (1.7 log(10)). EMC inactivation was > or =2.5 but < or =5.7 log(10). The caprylic acid treatment resulted in complete inactivation of the 3 LE viruses tested: BVDV (>6.6 log(10)), PRV (>6.6 log(10)), and VSV (>7.0 log(10)). For EMC no significant reduction was obtained (0.7 log(10)). Cumulative reduction was >13.6, >11.5, >8.3 and > or =2.5 for PRV, VSV, BVDV and EMC, respectively. Therefore the current manufacturing processes of at least some animal antisera already include production steps that can ensure robust viral inactivation of LE viruses and moderate inactivation of a NLE virus.     

Feasibility of methanogenic digestion applied to a low pH acetic acid solution

This paper discusses the methanogenic digestion of a synthetic acetic acid wastewater inoculated using a mixed culture obtained from an anaerobic digester at a municipal wastewater treatment facility. Experiments were conducted in 500mL batch reactors containing an unbuffered acetic acid solution. Test conditions compared methane production and acetic acid degradation at both acidic (pH 4.5) and neutral (pH 7.0) initial system conditions. Results showed that methane production increased by 30% when the initial pH was decreased from 7.0 to 4.5.     

Isolation,purification and characterization of pepsin soluble collagen isolated from silvertip shark (Carcharhinus albimarginatus) skeletal and head bone

Type II pepsin soluble collagens (PSC) were isolated from skeletal and head bone of silvertip shark; and examined for their biochemical and structural properties. Among the raw materials, the protein content (8.99%) was high in skeletal bone and the ash content (28%) was high in head bone. After the collagen extraction, the raw materials contained higher amount of ash content ranging from 82 to 88%. The hydroxyproline content of skeletal and skeletal PSC (30 and 113 mg/g) was higher than those head and head PSC. Both collagens were composed of two different α-chains (α₁- and α₂-chains) and were characterized as type II collagen. Amino acid analysis of skeletal and head PSC indicated imino acid contents of 156 and 175 amino acid residues per 1000 residues, respectively. Similar, Fourier transform infrared spectra of SCII and HCII were observed, which suggested that the isolation process did not affect the secondary structure and molecular order of collagen, particularly the triple–helical structure. Denaturation temperature of skeletal PSC (31 °C) was higher than that of head PSC. SEM microstructure of the collagens depicted a porous, fibrillary and multi-layered structure. These results suggested that the PSC isolated from skeletal and head bone of silvertip shark were found to be suitable biomaterial in commercial applications as alternatives to mammalian collagen.     

Isolation of residual lignin from softwood kraft pulp. Advantages of the acetic acid acidolysis method

Lignin in kraft pulp was extracted by enzymatic hydrolysis of the carbohydrates, acidolysis with dioxane-water-HCl (conventional method), and acidolysis with acetic acid-water-ZnCl2. The latter method was shown to extract lignin with a better yield than for conventional acidolysis and with a much lower content in impurities than for enzymatic hydrolysis. It was confirmed by 13C NMR analysis of the lignin samples that conventional hydrolysis modified the lignin polymer, causing the cleavage of some aryl-ether linkages. The cleavage was also observed on a model compound submitted to the same extraction conditions. In that respect, the acetic acid-water-ZnCl2 method was less damaging and consequently more suitable for analytical purposes.     

Preferential hydroxylation of type IV collagen by lysyl hydroxylase from Ehlers-Danlos syndrome type VI fibroblasts

Normal and Ehlers-Danlos syndrome type VI human skin and cornea fibroblasts were assayed for lysyl hydroxylase activity using two different collagen types as substrates. The enzyme from normal fibroblasts hydroxylated type I collagen more readily than type IV collagen. In the diseased cells the enzyme activity was significantly reduced, and the residual activity was preferentially directed towards type IV collagen. This suggests the existence of isoenzymes of lysyl hydroxylase or an alteration in the Ehlers-Danlos syndrome type VI that affects the binding of type I collagen more than that of type IV collagen.     

Isolation, by partial pepsin digestion, of the three collagen-like regions present in subcomponent Clq of the first component of human complement.

1. Digestion of human subcomponent C1q with pepsin at pH4.45 for 20h at 37 degrees C fragmented most of the non-collagen-like amino acid sequences in the molecule to small peptides, whereas the entire regions of collagen-like sequence that comprised 38% by weight of the subcomponent C1q were left intact. 2. The collagen-like fraction of the digest was eluted in the void volume of a Sephadex G-200 column, was was showm to be composed of two major fragments when examined by electrophoresis on polyacrylamide gels run in buffers containing sodium dodecyl sulphate. These fragments were separated on CM-cellulose at pH4.9 in buffers containing 7.5M-urea. 3. Human subcomponent C1q on reduction and alkylation yields equimolar amounnts of three chains, which have been designated A, B and C [Reid et al. (1972) Biochem. J. 130, 749-763]. One of the pepsin fragments was shown to be composed of the N-terminal 95 residues of the A chain linked, via residue A4, by a single disulphide bond to a residue in the sequence B2-B6 in the N-terminal 91 residues of the B chain. The second pepsin fragment was shown to be composed of a disulphide-linked dimer of the N-terminal 94 residues of the C chain, the only disulphide bond being located at residue C4.4. The mol. wts. of the unoxidized and oxidized pepsin fragments were estimated from their amino acid compositions to be 20 000 and 18 200 for the A-B and C-C dimers and 11 400, 8800 and 9600 for the collagen-like fragments of the A, B and C chains respectively. Estimation of the molecular weights of the peptic fragments by polyacrylamide-gel electrophoresis run in the presence of sodium dodecyl sulphate gave values that were approx. 50% higher than expected from the amino acid sequence data. This is probably due to the high collagen-like sequence content of these fragments.     

Concentration of hydrochloric acid and pepsin in gastric juice in dogs after starvation and refeeding

Feeding fogs with meat after a 3-day period of starvation increased hydrochloric acid concentration with subsequent return of the parameter to normal values. Under the same conditions, pepsin concentration decreased and raised up after re-feeding. Histamine administration following the starvation decreased hydrochloric acid concentration with subsequent normalising. In three days after re-feeding and histamine administration, pepsin concentration drooped owing, probably, to a decrease of parietal cell H2-receptor affinity to histamine. Pentagastrin administration after the starvation increased hydrochloric acid concentration. The findings suggest G-cell function inhibition occurring after a 3-day starvation which is important for the stomach mucous membrane protection.