Stichopus horrens flesh was explored as a potential source for generating peptides with angiotensin-converting enzyme (ACE) inhibitory capacity using 6 proteases, namely alcalase, flavourzyme, trypsin, papain, bromelain, and protamex. Degree of hydrolysis (DH) and peptide profiling (SDS-PAGE) of Stichopus horrens hydrolysates (SHHs) was also assessed. Alcalase hydrolysate showed the highest DH value (39.8) followed by flavourzyme hydrolysate (32.7). Overall, alcalase hydrolysate exhibited the highest ACE inhibitory activity (IC 50 value of 0.41 mg/mL) followed by flavourzyme hydrolysate (IC 50 value of 2.24 mg/mL), trypsin hydrolysate (IC 50 value of 2.28 mg/mL), papain hydrolysate (IC 50 value of 2.48 mg/mL), bromelain hydrolysate (IC 50 value of 4.21 mg/mL), and protamex hydrolysate (IC 50 value of 6.38 mg/mL). The SDS-PAGE results showed that alcalase hydrolysate represented a unique pattern compared to others, which yielded potent ACE inhibitory peptides with molecular weight distribution lower than 20 kDa. The evaluation of the relationship between DH and IC 50 values of alcalase and flavourzyme hydrolysates revealed that the trend between those parameters was related to the type of the protease used. We concluded that the tested SHHs would be used as a potential source of functional ACE inhibitory peptides for physiological benefits. � 2012 Bita Forghani et al.

Docosa Hexaenoic Acid (DHA) is an essential fatty acid that plays major role in human health. It is typically extracted from fatty fish and this puts pressure on global fish stock. DHA obtained from fish is also prone to contamination. Schizochytrium is a potential alternative source, having the ability of accumulating considerable amounts of DHA. Modification of medium components and culture conditions are the preferred techniques to enhance DHA production by this marine microalga. In this study, two-level factorial design was employed to investigate the significance of sea salt, glucose, yeast extract, Monosodium Glutamate (MSG) and peptone in affecting the biomass, lipid and DHA accumulation processes of a locally isolated strain of Schizochytrium. In contrast to the conventional ANOVA method commonly employed in various screening studies, half normal probability plots were used to identify the significant factors, whereas interaction plots were used to explain the pattern of interaction between significant combinations. Design Expert software was used to construct a set of experiments where each medium component mentioned above was varied over two levels. Cultivation was carried out in 250 mL flasks containing 50 mL of medium, incubated at 30�C with 200 rpm agitation for 96 h. This experiment revealed that sea salt and interaction of glucose-MSG have significant effect on biomass production whereas sea salt and interaction of sea salt-glucose affected lipid accumulation. Meanwhile, interactions of glucose-yeast extract and glucose-MSG have significant effect on DHA accumulation. Detailed analysis of interaction plots enabled deeper understanding of the behavior of the system in response to the significant variables, which improves the precision in determination of variable domains for effective medium optimization. 2014 Science Publication.

Strategic feeding of ammonium and metal ions (Mg2+, Mn 2+, Fe3+, Cu2+, Ca2+, Co 2+, and Zn2+) for enhanced GLA-rich lipid accumulation in C. bainieri 2A1 was established. When cultivated in nitrogen-limited medium, the fungus produced up to 30% lipid (g/g biomass) with 12.9% (g/g lipid) GLA. However, the accumulation of lipid stopped at 48 hours of cultivation although glucose was abundant. This event occurred in parallel to the diminishing activity of malic enzyme (ME), fatty acid synthase (FAS), and ATP citrate lyase (ACL) as well as the depletion of metal ions in the medium. Reinstatement of the enzymes activities was achieved by feeding of ammonium tartrate, but no increment in the lipid content was observed. However, increment in lipid content from 32% to 50% (g/g biomass) with 13.2% GLA was achieved when simultaneous feeding of ammonium, glucose, and metal ions was carried out. This showed that the cessation of lipid accumulation was caused by diminishing activities of the enzymes as well as depletion of the metal ions in the medium. Therefore, strategic feeding of ammonium and metal ions successfully reinstated enzymes activities and enhanced GLA-rich lipid accumulation in C. bainieri 2A1. � 2014 Shuwahida Shuib et al.