Ulčar Barbara, Regueira Alberte, Podojsteršek Maja, Boon Nico, Ganigué Ramon
Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium.
Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium.
Front Bioeng Biotechnol. 2024 Jan 11;11:1291007. doi: 10.3389/fbioe.2023.1291007. eCollection 2023.
Efficient waste management is necessary to transition towards a more sustainable society. An emerging trend is to use mixed culture biotechnology to produce chemicals from organic waste. Insights into the metabolic interactions between community members and their growth characterization are needed to mediate knowledge-driven bioprocess development and optimization. Here, a granular sludge bioprocess for the production of caproic acid through sugar-based chain elongation metabolism was established. Lactic acid and chain-elongating bacteria were identified as the two main functional guilds in the granular community. The growth features of the main community representatives (isolate G03 for lactic acid bacteria and type strain for chain-elongating bacteria) were characterized. The measured growth rates of lactic acid bacteria (0.051 ± 0.005 h) were two times higher than those of chain-elongating bacteria (0.026 ± 0.004 h), while the biomass yields of lactic acid bacteria (0.120 ± 0.005 g biomass/g glucose) were two times lower than that of chain-elongating bacteria (0.239 ± 0.007 g biomass/g glucose). This points towards differential growth strategies, with lactic acid bacteria resembling that of a r-strategist and chain-elongating bacteria resembling that of a K-strategist. Furthermore, the half-saturation constant of glucose for was determined to be 0.35 ± 0.05 g/L of glucose. A linear trend of caproic acid inhibition on the growth of was observed, and the growth inhibitory caproic acid concentration was predicted to be 13.6 ± 0.5 g/L, which is the highest reported so far. The pre-adjustment of to 4 g/L of caproic acid did not improve the overall resistance to it, but did restore the growth rates at low caproic acid concentrations (1-4 g/L) to the baseline values (i.e., growth rate at 0 g/L of caproic acid). High resistance to caproic acid enables lactic acid bacteria to persist and thrive in the systems intended for caproic acid production. Here, insights into the growth of two main functional guilds of sugar-based chain elongation systems are provided which allows for a better understanding of their interactions and promotes future bioprocess design and optimization.
高效的废物管理对于向更可持续的社会转型至关重要。一个新兴趋势是利用混合培养生物技术从有机废物中生产化学品。为了推动基于知识的生物过程开发和优化,需要深入了解群落成员之间的代谢相互作用及其生长特性。在此,建立了一种通过基于糖的链延长代谢生产己酸的颗粒污泥生物过程。乳酸细菌和链延长细菌被确定为颗粒群落中的两个主要功能类群。对主要群落代表(乳酸菌的分离株G03和链延长细菌的模式菌株)的生长特性进行了表征。测得的乳酸菌生长速率(0.051±0.005 h⁻¹)是链延长细菌(0.026±0.004 h⁻¹)的两倍,而乳酸菌的生物量产量(0.120±0.005 g生物量/g葡萄糖)比链延长细菌(0.239±0.007 g生物量/g葡萄糖)低两倍。这表明了不同的生长策略,乳酸菌类似于r-策略者,链延长细菌类似于K-策略者。此外,确定了葡萄糖对该菌的半饱和常数为0.35±0.05 g/L葡萄糖。观察到己酸对该菌生长的抑制呈线性趋势,并预测生长抑制性己酸浓度为13.6±0.5 g/L,这是迄今为止报道的最高值。将该菌预调节至4 g/L己酸并不能提高其对己酸的总体抗性,但确实将低己酸浓度(1 - 4 g/L)下的生长速率恢复到基线值(即0 g/L己酸时的生长速率)。对己酸的高抗性使乳酸菌能够在用于己酸生产的系统中持续存在并茁壮成长。在此,提供了对基于糖的链延长系统的两个主要功能类群生长的见解,这有助于更好地理解它们之间的相互作用,并促进未来生物过程的设计和优化。