Microbial gamma-glutamyl transpeptidase (GGT) is a key enzyme in production of several γ-glutamyl compounds with food and pharmaceutical applications. Bacterial GGTs are not commercially available in the market owing to their low production from various sources. Thus, the study was focused on achieving the higher GGT production from B. altitudinis IHB B1644 by optimizing the culture conditions using one-variable-at-a-time (OVAT) strategy. A mesophillic temperature of 28 °C, agitation 200 rpm and neutral pH 7 were found to be optimal for higher GGT titre. Among the medium components, the monosaccharide glucose served as the best carbon source over disaccharides, and yeast extract was the preferred organic nitrogen source over inorganic nitrogen sources. The statistical approaches (Plakett–Burman and response surface methodology) were further employed for the optimization of medium components. Medium composition: 0.1% w/v glucose, 0.3% w/v yeast extract, 0.03% w/v magnesium sulphate, 0.20% w/v potassium dihydrogen phosphate and 2.5% w/v sodium chloride with inoculum size (1% v/v) was suitable for higher GGT titres (449 U ml⁻¹). Time kinetics showed the stability of enzyme up to 96 h of incubation suggesting its application in the industrial use. The proposed strategy resulted in 2.6-fold increase in the GGT production compared to that obtained in the unoptimized medium. The results demonstrated that RSM was fitting to identify the optimum production conditions and this finding should be of great importance for commercial GGT production.

微生物γ-谷氨酰转肽酶（GGT）是在食品和药物应用中生产几种γ-谷氨酰化合物的关键酶。细菌GGT由于来自各种来源的低产量而不能在市场上买到。因此，该研究的重点是从高产双歧杆菌中获得更高的GGT产量通过使用一次可变（OVAT）策略优化培养条件来实现IHB B1644。发现中温温度为28°C，搅拌速度为200 rpm，中性pH为7时，GGT滴度更高。在培养基成分中，单糖葡萄糖是二糖的最佳碳源，酵母提取物是无机氮的首选有机氮源。统计方法（Plakett-Burman和响应面方法）被进一步用于优化培养基成分。中等成分：0.1％w / v葡萄糖，0.3％w / v酵母提取物，0.03％w / v硫酸镁，0.20％w / v磷酸二氢钾和2.5％w / v氯化钠，接种量为（1％v / v v）适用于更高的GGT滴度（449 U ml ^-1）。时间动力学表明酶在长达96 h的温育中具有稳定性，表明其在工业中的应用。与未优化培养基相比，拟议的策略导致GGT产量增加了2.6倍。结果表明，RSM适合确定最佳生产条件，这一发现对于商业化的GGT生产应具有重要意义。