Production of Calcium Lactobionate by a Lactose-oxidizing Enzyme from <i>Paraconiothyrium</i> sp. KD-3

Abstract

A lactose-oxidizing enzyme was obtained from culture supernatant of a fungal strain of Paraconiothyrium sp. KD-3. The enzyme was a flavoprotein with a molecular mass of 54 kDa. The purified enzyme oxidized various monosaccharides and oligosaccharides such as D-glucose, D-galactose, D-xylose, cellooligosaccharides and maltooligosaccharides in addition to lactose, using molecular oxygen as a good electron acceptor, to accumulate the corresponding aldonic acids and hydrogen peroxide. The Paraconiothyrium enzyme was suitable for the production of calcium lactobionate compared with a commercial hexose oxidase owing to the stability during the conversion. The enzyme converted 10 20% (w v) lactose completely to calcium lactobionate in a 500-mL reactor under aeration, agitation and pH regulation at 5.5. The neutralization was successfully performed by the addition of 10% (w w) slurry of calcium carbonate, while neutralization with 25% (w v) sodium hydroxide solution inactivated the enzyme gradually. The supplement of catalase to the mixture promoted the conversion by degrading hydrogen peroxide. The immobilized enzyme, which was prepared by the adsorption to a cation exchange resin followed by the condensation with carbodiimide, oxidized 18.5% (w v) lactose to produce calcium lactobionate in a batch reaction. Calcium lactobionate and aldonates derived from D galactose, D-xylose and L-arabinose showed high aqueous solubility and low calcium binding capability.

Lactobionic Acid as a Potential Food Ingredient: Recent Studies and Applications

“…Most recent studies focus on biotechnological processes to obtain LBA (microbial enzymatic routes), which are extremely promising systems concerning the cost and benefit factors. However, like most biological systems, these methods still need to be improved so they overcome the inherent barriers to the process and achieve efficiency (Alonso et al., ; Gupta, Treichel, Shapaval, Tuohy, & Oliveira, ; Miyamoto, Ooi, & Kinoshita, ; Murakami, Kiryu, Kiso, & Hirofumi, ). Besides several studies have been carried out, using different microorganisms and enzymes, with or without electron acceptor, there is no established industrial‐scale method for the production of LBA so far (Alonso et al., ).…”

“…Later on in the 90s, the use of gold and platinum electrodes resulted in higher acid yields (90% to 100%) (Druliolle, Kokoh, & Beden, 1994;Druliolle, Kokoh, Hahn, Lamy, & Beden, 1997). The oxidation process involved in electrolysis requires a large amount of energy, it is expensive and environmentally harmful due to the metal catalysts as well as the process residues (Alonso et al, 2013;Gupta et al, 2017;Miyamoto et al, 2000;Murakami et al, 2008). Not surprisingly, the traditional electrolytic method is the main reason for the imposition of legal barriers to LBA.…”

“…For its use as a food ingredient, it is necessary to be accepted and registered as such, and for this it is demanded a thorough toxicological report and deep studies with laboratorial animal tests (Krewski et al., ). Generally, calcium salts have low solubility in water (Sendroy & Baird, ) and the lactobionate appears as a water‐soluble salt, demonstrating technological advantage over the others, together with sodium and potassium lactobionates (Malvessi et al., ; Murakami et al., ).…”

Conversion of Lactose to Calcium Lactobionate by Some Bacterial Species

“…The use of glucose dehydrogenase (fructose) of Zymomonas mobilis for the continuous production of lactobionic acid from lactose in an ultrafilteration membrane reactor was reported (Satory et al,1997). Glucose dehydrogenase (EC1.1.1.47) from Pseudomonas graveolence (Nishizuka and Hayaishi,1962) catalyzes oxidation of lactose ,maltose and cellobiose, producing their aldobionic-δ-lactone in the presence of an appropriate hydrogen acceptor.Biological reactions have general advantages such as high selectivity for reactions as well as substrates,high efficiency ,simple reaction systems, mild reaction conditions and avoidance of poisonous chemicals (Murakami et al,2008). Lactobionic acid (lacA) has several practical potential uses such as ingredient in solutions stabilizing organs before transplanation.…”

“…Among these examples of practical and potential usefulness, we are interested in high aqueous solubility of the mineral salts of lacA.Two glycosyl moieties and carboxyl group enable the high solubility: calcium lactobionate dissolves at approximately 62 g\100 ml ,which is almost 10-60 times higher than calcium gluconate , lactate and citrate 28,000 times higher than calcium carbonate , an ingredient commonly used for foods and beverages. Highly soluble calcium salt, e.g., calcium chloride, has bitter taste,whereas calcium bionate has no peculiar and relatively high threshold concentration (Murakami et al,2008).…”