In the current work, date wastes were used for lactic acid (LA) production under thermo-alkaline conditions to overcome some fermentation challenges. Amongst 27 bacterial isolates that produced LA from date juice, isolate D-218 exhibited better growth stability and LA production under various stressed conditions. This isolate was characterized as Bacillus coagulans D-218 using physiological and molecular identification methods. In batch fermentation mode, strain D-218 could not completely utilize 80 g/L of the total sugar and produced only 45.8 ± 2.8 g/L of LA at LA productivity of 0.214 g/L.h and high residual sugar (29.2 g/L) was unutilized in the fermentation media. Different repeated batch fermentations with different initial sugar concentrations and gradual increase in sugar concentrtions were conducted to maximize LA productivity. Starting with 60 g/L of total sugar, four runs of repeated batch fermentations were conducted that enhanced the LA productivity (70%) to 0.49 g/L.h. Another 9 runs were initiated with 40 g/L which further improved LA productivity that reached up to 0.77 g/L.h. Surprisingly, initiating fermentations with 20 g/L of total sugar successfully attained long-term fermentation (18 runs) with high LA yield and productivity without carbon loss of initiated startup sugar of date waste. In this process, strain D-218 could completely consume 80 g/L sugars with high LA production titer (72.9 ± 0.56 g/L), yield (0.92 g/g), and productivity (0.71 g/L.h). This study is the first to exploit date waste in a cost-effective system for high-titer lactic acid production under thermo-alkaline conditions (pH 9.0; 50 °C) and to report repeated batch fermentation for LA production from date wastes.

在当前工作中，将枣废料用于在热碱条件下生产乳酸（LA），以克服某些发酵难题。在从枣汁中产生LA的27种细菌分离物中，分离物D-218在各种胁迫条件下均表现出更好的生长稳定性和LA产生。该分离物的特征为凝固芽孢杆菌D-218采用生理和分子鉴定方法。在分批发酵模式下，菌株D-218不能完全利用80 g / L的总糖，仅以LA生产力为0.214 g / Lh和高残留糖分（29.2 g / L）的情况下仅产生45.8±2.8 g / L的LA。在发酵培养基中未被利用。进行了不同的重复分批发酵，发酵的初始糖浓度不同，糖浓度逐渐增加，以最大限度地提高LA生产率。从60 g / L的总糖开始，进行了四批重复的分批发酵，将LA的生产率（70％）提高到0.49 g / Lh。另外9批以40 g / L的水平开始，进一步提高了LA的生产率。达到0.77 g / Lh 以20 g / L的总糖开始发酵成功地实现了长期发酵（18次运行），具有很高的LA产量和生产率，而没有启动糖的浪费。在此过程中，菌株D-218可以完全消耗80 g / L的糖，具有高的LA产量效价（72.9±0.56 g / L），产量（0.92 g / g）和生产率（0.71 g / Lh）。这项研究是首次在经济高效的系统（pH 9.0； 50°C）下，在经济高效的乳酸生产系统中利用椰枣废料，并报道了从椰枣废料中重复生产LA的发酵过程。和生产率（0.71 g / Lh）。这项研究是首次在经济高效的系统（pH 9.0； 50°C）下，在经济高效的乳酸生产系统中利用椰枣废料，并报道了从椰枣废料中重复生产LA的发酵过程。和生产率（0.71 g / Lh）。这项研究是首次在经济高效的系统（pH 9.0； 50°C）下，在经济高效的乳酸生产系统中利用椰枣废料，并报道了从椰枣废料中重复生产LA的发酵过程。