Whey, the main by-product obtained from the manufacture of cheese, which contains a very high organic load (mainly due to the lactose content), is not easily degradable and creates concern over environmental issues. Hydrolysis of lactose present in whey and conversion of whey lactose into valuable products such as bioethanol, sweet syrup, and animal feed offers the possibility of whey bioremediation. The increasing need for bioremediation in the dairy industry has compelled researchers to search for a novel source of β-galactosidase with diverse properties. In the present study, the bacterium Paracoccus marcusii KGP producing β-galactosidase was subjected to morphological, biochemical, and probiotic characterisation. The bacterial isolate was found to be non-pathogenic and resistant to low pH (3 and 4), bile salts (0.2%), salt (10%), pepsin (at pH 3), and pancreatin (at pH 8). Further characterisation revealed that the bacteria have a good auto-aggregation ability (40% at 24 h), higher hydrophobicity (chloroform-60%, xylene-50%, and ethyl acetate-40%) and a broad spectrum of antibiotic susceptibility. The highest growth of P. marcusii KGP was achieved at pH 7 and 28 °C, and the yeast extract, galactose, and MgSO₄ were the best for the growth of the bacterial cells. The bacterium KGP was able to utilise whey as a substrate for its growth with good β-galactosidase production potential. Furthermore, the β-galactosidase extracted from the isolate KGP could hydrolyse 47% whey lactose efficiently at 50 °C. The study thus reveals the potential application of β-galactosidase from P. marcusii KGP in whey bioremediation.

乳清是从奶酪制造中获得的主要副产品，它含有非常高的有机负荷（主要是由于乳糖含量），不易降解并引起对环境问题的担忧。乳清中乳糖的水解和乳清乳糖转化为有价值的产品，如生物乙醇、甜糖浆和动物饲料，为乳清生物修复提供了可能性。乳制品行业对生物修复的需求不断增加，迫使研究人员寻找具有多种特性的 β-半乳糖苷酶的新来源。在本研究中，Paracoccus marcusii细菌对产生 KGP 的 β-半乳糖苷酶进行形态学、生化和益生菌表征。发现该细菌分离物是非致病性的，并且对低 pH（3 和 4）、胆盐（0.2%）、盐（10%）、胃蛋白酶（pH 3）和胰酶（pH 8）具有抗性。进一步表征表明，该细菌具有良好的自聚集能力（24 小时为 40%）、更高的疏水性（氯仿 60%、二甲苯 50% 和乙酸乙酯 40%）和广谱抗生素敏感性。P. marcusii KGP 在 pH 7 和 28 °C 下生长最快，酵母提取物、半乳糖和 MgSO ₄最有利于细菌细胞的生长。细菌 KGP 能够利用乳清作为其生长的底物，并具有良好的 β-半乳糖苷酶生产潜力。此外，从分离株 KGP 中提取的 β-半乳糖苷酶可以在 50°C 下有效水解 47% 的乳清乳糖。因此，该研究揭示了来自P. marcusii KGP的 β-半乳糖苷酶在乳清生物修复中的潜在应用。