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The water-soluble protein from Phascolosoma esculenta was hydrolyzed by pepsin to obtain the hydrolysate with angiotensin I-converting enzyme (ACE) inhibitory activity. The hydrolysate (PEPH) was then further separated by membrane bioreactor system, ion-exchange chromatography, gel filtration, and reversed phase high-performance liquid chromatography (RP-HPLC) and a novel ACE inhibitory peptide named as PeP with the IC50 value of 135 M was isolated. The amino acid sequence, Ala-Trp-Leu-His-Pro-Gly-Ala-Pro-Lys-Val-Phe, was identified by matrix-assisted laser desorption ionization-time of flight/time of flight (MALDI-TOF/TOF). Inhibitory kinetics study suggested that PeP acted as competitive inhibitor against ACE. Single oral administration of synthesized PeP at 10 mg/kg dose in spontaneously hypertensive rats could reduce the systolic blood pressure around 30 mmHg and the effect could last for more than 8 h. The results suggest that peptide from P. esculenta could be a potent natural ingredient for functional foods or pharmaceuticals against hypertension.

In this work, different processes including lactic acid bacteria fermentation, glucono-δ-lactone (GDL) coagulation and enzymatic hydrolysis were applied to produce soy cheese spread without any milk solid and/or alkaline metal caseinates added. All the soy cheese spread samples were studied with respect to the differences in the textural properties - utilizing TPA and rheological behavior, besides their microstructural features and sensory assessment. In addition, urea-SDS-PAGE assay was used to investigate the proteolysis in enzymatic hydrolysis process. As a result, the soy cheese spread sample produced by the combined use of GDL and lactic acid bacteria fermentation together with enzymatic hydrolysis process, was observed with better spread-ability, more acceptable sensory features, and stable homogeneous structure than other samples. [ABSTRACT FROM AUTHOR]

Escherichia coli DH5α grows poorly in a chemically defined medium, but its acetate-tolerant mutant, DA19, grows fast and produces less acetate. To investigate the differences in metabolism between the two strains, the samples of continuous cultures at steady state were analyzed by two-dimensional SDS-PAGE (2-D SDS-PAGE) and peptide mass fingerprinting (PMF). The results indicated that in DA19, expression of gnd, yddS, and purH (except for adenine supplement) was up-regulated, and expression of atpA, glnK, and ompR, which encode membrane proteins, was significantly up-regulated. Expression of ackA and yahK in DA19 was down-regulated. In the presence of acetate, hchA and ydcW in DH5α were significantly down-regulated. This study shed light on the differences in metabolic properties between DH5α and DA19, and provided some ideas for improving strains through metabolic engineering. [ABSTRACT FROM AUTHOR]

In fed-batch culture of Klebsiella pneumoniae, 1,3-propanediol production was growth associated, while the by-products, including lactic acid and ethanol, increased sharply as the cells grew slowly. When the fed-batch culture was supplied with a mixture of organic acids including citrate, fumarate and succinate, cell growth and 1,3-propanediol production increased significantly, whereas the by-products, especially lactic acid and ethanol, decreased sharply. High concentrations of PDO and acetate inhibited cell growth and PDO production. To improve the PDO production, repeated fed-batch culture with addition of the organic acid mixture was performed in a 5-l reactor. The fed-batch culture was repeated five times, and the 1,3-propanediol yield and concentration reached above 0.61 mol mol−1 and 66 g l−1, respectively, in 20 h for each cycle. Furthermore, the PDO productivity reached above 3.30 g l−1 h−1 in each cycle, which was much higher than that of the original fed-batch culture. [ABSTRACT FROM AUTHOR]