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    Factors affecting acid protease production by Mucor circinelloides MG603064.1 through SmF process: characterization and fromage frais making
    (BioTechnologia, 2023) Bensmail, Souhila; Boudjema, Khaled; Naimi-Fazouane, Fethia; Bensmail, Samira; Djouahra-Fahem, Djamila; Ferhoum, Fatiha; Bourfis, Nassima
    The exploitation of food industry wastes and their conversion into value-added products present a promising and continuously growing field, given the diversity of elaborated wastes. The current work aimed to utilize sweet cheese whey as a growth medium for acid protease production by a local fungus strain. The biochemical and physicochemical properties of the cheese whey, such as pH, conductivity, chemical oxygen demand, biological oxygen demand (BOD5), total nitrogen and protein contents, and mineral salts, were assessed using various analytical methods. The effect of certain parameters on acid protease production by Mucor circinelloides MG603064.1 through the SmF process was investigated using the conventional design method "One factor at a time". Subsequent to characterization, the crude extract was used in a trial to create fromage frais, compared to the commercial rennin CHY-MAX® Powder Extra. Cheese whey characterization revealed its richness in total nitrogen (1.044 ± 0.044 g/l), protein content (6.52 ± 0.04 g/l), and principal mineral salts: calcium (1.637 ± 0.037 g/l), phosphorus (1.173 ± 0.023 g/l), and chloride (1.66 ± 0.09 g/l). The optimal values of the SmF process for acid protease production, such as the inoculum size, beef extract, and KH2PO4 supplements, the initial pH of cheese whey, and incubation temperature were, respectively, 11% (v/v), 0.4% (w/v), 0.5% (w/v), 5.5, and 30°C. Under these conditions, the lowest milk-clotting time of 290 s was achieved, representing an 18.41-fold increase compared to the initial step using the unoptimized medium. The enzyme showed maximum milk-clotting activity at pH 5, a temperature of 60°C, and in the presence of 0.025 M of CaCl2. The enzyme activity also significantly improved with sonication (35 kHz) for 10 min. The crude extract of M. circinelloides ensured the production of fresh cheese samples with characteristics roughly similar to those obtained by the control (CHY-MAX® rennin). The acid protease of M. circinelloides could successfully substitute the conventional rennin in the manufacture of fresh cheese.
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    Efficient and cost-effective production of Bacillus thuringiensis subsp. aizawai spores and delta-endotoxins using agricultural raw materials and agro-industrial wastes under submerged fermentation
    (Elsevier, 2022) Gounina-Allouane, Rabia; Acheuk, Fatma; Sahir-Halouane, Fatma
    In this study, cost-effective liquid culture media based on agricultural raw materials and agro-industrial wastes were developed for spores and delta-endotoxins production by a strain of B. thuringiensis subsp. aizawai used as a larvicide in wax moths control. The raw materials used include edible leguminous seeds, corn, wheat bran, dry palm date pulps, and corn forages. The agro-industrial wastes were dry palm dates pits and olive mill solid wastes. The protein and carbohydrate contents of the developed media were measured. Sporulation on the different developed media was monitored and delta-endotoxins produced were quantified. Mono-component media containing chickpea, red lentils, and wheat bran produced a spore count compared to the reference medium NYSM. The results showed that the dry palm date's pulp extract was the most efficient medium for spore production (1.43 × 1010 spores ml−1), and the chickpea medium was the most efficient for delta-endotoxins production