Improvement of enzymatic performance of Asclepias curassavica L. proteases by immobilization. Application to the synthesis of an antihypertensive peptide

Exploration and Molecular Identification of Proteolytic Bacteria as Probiotic Candidates from Shrimp Ponds in West Sumatra, Indonesia

<b>Background and Objective:</b> The existence of intensive shrimp aquaculture faces serious challenges in the form of a decrease in pond water quality due to overfeeding. Efforts are needed to improve pond water quality by utilizing proteolytic bacterial isolates to break down suspended or accumulated feed on the pond bottom. The research aims to find proteolytic bacterial isolates from pond sediments and the digestive tract of shrimp (<i>Litopenaeus vannamei</i>). <b>Materials and Methods:</b> The materials needed are pond sediment samples, shrimp digestive tract, seawater complete agar (SWCA) medium and skim milk agar medium (SMA). The study used survey methods to determine sampling locations and continued with experimental methods in the laboratory. Nine isolates were obtained from pond sediments and two bacterial isolates were from the shrimp digestive tract. <b>Results:</b> The proteolytic potency test showed that two isolates from pond sediments and one isolate from the digestive tract of shrimp were positive for proteolytic. The largest proteolytic index value reached 6.357. Molecular identification by analyzing the <i>16S rRNA</i> gene sequence shows that PC23 isolate is closely related to the bacterium <i>Exiguobacterium indicum </i>strain KR6 with percent identity 99.44-99.58% and PU32 isolate with <i>Bacillus cereus</i> strain 125 with percent identity 100%. <b>Conclusion:</b> The bacteria obtained can be used as probiotic candidates for the future are <i>Exiguobacterium indicum</i> strain KR6 and <i>Bacillus cereus</i> strain 125.

Enzymatic synthesis of new antimicrobial peptides for food purposes

Growing consumer awareness of the potential negative health effects of synthetic antibiotics has prompted the search for more natural preservatives that can improve the safety and quality of food. In this study we report the enzymatic synthesis of N-α-[Carbobenzyloxy]-Ile-Gln (Z-IQ) which is the precursor of Ile-Gln (IQ), a new antibacterial dipeptide, using an aqueous-organic biphasic system formed by 50% (v/v) ethyl acetate in 0.1 M Tris - HCl buffer pH 8. A partially purified proteolytic extract from the fruits of Solanum granuloso leprosum, named granulosain, proved to be a robust biocatalyst for the synthesis of Z-IQ, eliciting 71 ± 0.10% maximal peptide yield in the above described conditions. After cleaving and purifying IQ dipeptide, antimicrobial activity was assayed against Staphylococcus aureus ATCC 25923, Staphylococcus hominis A17771, and Staphylococcus aureus C00195, and MIC values between 118 ± 0.01 μg/mL and 133.7 ± 0.05 μg/mL were obtained. In addition, IQ showed MIC of 82.4 ± 0.01 μg/mL and 85.0 ± 0.00 μg/mL against Escherichia coli ATCC 25922 and Escherichia coli A17683, respectively. IQ did not show inhibitory activity against single-drug resistance (SDR) strains, such as Klebsiella oxytoca A19438 (SDR) and Pseudomonas aeruginosa C00213 (SDR), and against multidrug-resistant Enterococcus faecalis I00125 (MDR). IQ also caused growth inhibition of Helicobacter pylori NCTC 11638 and three wild-type H. pylori strains, which are sensitive to AML, MTZ, LEV and CLA (H. pylori 659), resistant to LEV (H. pylori 661 SDR), and resistant to MTZ (H. pylori 662 SDR). Finally, this study contributes with a new dipeptide (IQ) that can be used as an antimicrobial agent for food preservation or as a safe ingredient of functional foods.

Production of Plant Proteases and New Biotechnological Applications: An Updated Review

An updated review of emerging plant proteases with potential biotechnological application is presented. Plant proteases show comparable or even greater performance than animal or microbial proteases for by-product valorization through hydrolysis for, for example, cheese whey, bird feathers, collagen, keratinous materials, gelatin, fish protein, and soy protein. Active biopeptides can be obtained as high added value products, which have shown numerous beneficial effects on human health. Plant proteases can also be used for wastewater treatment. The production of new plant proteases is encouraged for the following advantages: low cost of isolation using simple procedures, remarkable stability over a wide range of operating conditions (temperature, pH, salinity, and organic solvents), substantial affinity to a broad variety of substrates, and possibility of immobilization. Vegetable proteases have enormous application potential for the valorization of industrial waste and its conversion into products with high added value through low-cost processes.