Song Liang, Liu Shiyu, Liu Rui, Yang Donghai, Dai Xiaohu
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Sci Total Environ. 2022 Sep 20;840:156479. doi: 10.1016/j.scitotenv.2022.156479. Epub 2022 Jun 6.
China is vigorously promoting garbage classification, but the treatment of classified waste, especially household food waste (HFW) has yet to be studied. Lactic acid (LA), a high value-added platform molecule has broad market prospects. Although there have been many studies on the production of LA from food waste, open fermentation often produces lots of by-products, while the traditional fermentation under a pure bacteria system often requires the saccharification process, which increases the production cost. We sought to analyze the comprehensive properties of classified HFW in Shanghai, then to produce LA by inoculating lactic acid bacteria (LAB) directly. The effects of strains, temperature, sterilized or not, initial pH, inoculum size, and substrate concentration on LA production were investigated. HFW was rich in nutrients and growth factors which provided the possibility for direct LA production from HFW by inoculating LAB. The results showed that Lactobacillus rhamnosus ATCC 7469, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus all could be used as the inoculum, however, no significant synergistic effect of the three strains on LA production was found. LA concentration of 30.25 g/L at 37 °C, pH 6.8 could be obtained by inoculating Lactobacillus rhamnosus ATCC 7469 from sterilized HFW. High inoculum size and substrate concentration resulted in high LA concentration, but not high LA yield. The result of ANOVA indicated that there was a significantly positive relationship between substrate concentration and LA concentration (r = 0.942, p < 0.01), while no statistically significant difference between these groups at different inoculum size was evident (p = 0.318). In addition, an average LA concentration of 26.8 g/L, LA yield of 0.20 g/g TCOD was obtained by repeated batch fermentation for 32 d.
中国正在大力推进垃圾分类，但分类垃圾的处理，尤其是家庭食物垃圾的处理，仍有待研究。乳酸是一种高附加值的平台分子，具有广阔的市场前景。尽管已有许多关于利用食物垃圾生产乳酸的研究，但开放式发酵往往会产生大量副产物，而纯细菌系统下的传统发酵通常需要糖化过程，这增加了生产成本。我们试图分析上海分类家庭食物垃圾的综合特性，然后通过直接接种乳酸菌来生产乳酸。研究了菌株、温度、是否灭菌、初始pH值、接种量和底物浓度对乳酸产量的影响。家庭食物垃圾富含营养物质和生长因子，这为通过接种乳酸菌直接从家庭食物垃圾生产乳酸提供了可能性。结果表明，鼠李糖乳杆菌ATCC 7469、德氏保加利亚乳杆菌亚种和嗜热链球菌都可作为接种物，然而，未发现这三种菌株对乳酸生产有显著的协同作用。通过接种来自灭菌家庭食物垃圾的鼠李糖乳杆菌ATCC 7469，在37℃、pH 6.8条件下可获得30.25 g/L的乳酸浓度。高接种量和高底物浓度导致高乳酸浓度，但乳酸产率不高。方差分析结果表明，底物浓度与乳酸浓度之间存在显著正相关（r = 0.942，p < 0.01），而不同接种量组之间无统计学显著差异（p = 0.318）。此外，通过32天的重复分批发酵，平均乳酸浓度为26.8 g/L，乳酸产率为0.20 g/g TCOD。
