Photo-fermentative bacteria aggregation triggered by L-cysteine during hydrogen production.
Photo-fermentative bacteria aggregation triggered by L-cysteine during hydrogen production.
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产氢过程中 L-半胱氨酸引发的光发酵细菌聚集
DOI：
10.1186/1754-6834-6-64
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发表时间：
2013-05-03
影响因子：
6.3
通讯作者：
Ren NQ
中科院分区：
文献类型：
--
作者：
Xie GJ;Liu BF;Xing DF;Nan J;Ding J;Ren NQ
背景通过光发酵细菌（PFB）从有机废物和太阳能中回收氢气被认为是一种有前景的生物能源策略。然而，由于PFB絮凝性差，使用PFB制氢通常会遭受光生物反应器中生物质严重冲刷的问题。在连续运行过程中，PFB细胞无法有效地与上清液分离，并随反应器出水不断冲出，导致出水浊度增加，同时导致污染物增加。此外，为了补充生物量流失，底物持续用于细胞生长而不是氢气生产。因此，絮凝性差不仅使出水水质恶化，而且降低了底物产氢的潜在产率。因此，增强PFB的絮凝性对于进一步发展光发酵过程是迫切需要的。结果在这里，我们证明L-半胱氨酸可以提高粪红假单胞菌RLD-53的产氢量，更重要的是，同时引发PFB的显着聚集。实验表明，L-半胱氨酸极大地促进了胞外聚合物的产生，特别是含有较多二硫键的蛋白质的分泌，有利于增强PFB絮体的稳定性。通过形成二硫键，L-半胱氨酸不仅促进EPS的产生，特别是蛋白质的分泌，而且稳定了EPS中蛋白质的最终确认。此外，细胞表面元素和功能基团，特别是表面带电基团，也被L-半胱氨酸改变。因此，绝对zeta电位在L-半胱氨酸为1.0 g/l时达到最小值，根据DLVO理论，这明显降低了静电排斥相互作用能。总相互作用能垒从L-半胱氨酸0.0 g/l时的389.77 KT下降到1.0 g/l时的127.21 kT。结论因此，菌株RLD-53克服了总相互作用能垒并有效絮凝。经过短暂的沉降后，冲出的生物质会明显减少，在连续运行中出水水质会得到很大的改善。此外，PFB的聚集可以实现光生物反应器的高生物量滞留，这使得光生物反应器能够在低水力停留时间和高有机负载率下运行。因此，所描述的光产氢过程中的絮凝行为可能适合实际应用。
BackgroundHydrogen recovered from organic wastes and solar energy by photo-fermentative bacteria (PFB) has been suggested as a promising bioenergy strategy. However, the use of PFB for hydrogen production generally suffers from a serious biomass washout from photobioreactor, due to poor flocculation of PFB. In the continuous operation, PFB cells cannot be efficiently separated from supernatant and rush out with effluent from reactor continuously, which increased the effluent turbidity, meanwhile led to increases in pollutants. Moreover, to replenish the biomass washout, substrate was continuously utilized for cell growth rather than hydrogen production. Consequently, the poor flocculability not only deteriorated the effluent quality, but also decreased the potential yield of hydrogen from substrate. Therefore, enhancing the flocculability of PFB is urgent necessary to further develop photo-fermentative process.ResultsHere, we demonstrated that L-cysteine could improve hydrogen production ofRhodopseudomonas faecalisRLD-53, and more importantly, simultaneously trigger remarkable aggregation of PFB. Experiments showed that L-cysteine greatly promoted the production of extracellular polymeric substances, especially secretion of protein containing more disulfide bonds, and help for enhancement stability of floc of PFB. Through formation of disulfide bonds, L-cysteine not only promoted production of EPS, in particular the secretion of protein, but also stabilized the final confirmation of protein in EPS. In addition, the cell surface elements and functional groups, especially surface charged groups, have also been changed by L-cysteine. Consequently, absolute zeta potential reached a minimum value at 1.0 g/l of L-cysteine, which obviously decreased electrostatic repulsion interaction energy based on DLVO theory. Total interaction energy barrier decreased from 389.77 KT at 0.0 g/l of L-cysteine to 127.21 kT at 1.0 g/l.ConclusionsThus, the strain RLD-53 overcame the total energy barrier and flocculated effectively. After a short settlement, the biomass rush out will be significantly reduced and the effluent quality will be greatly improved in the continuous operation. Furthermore, aggregation of PFB could enable high biomass hold-up of photobioreactor, which allows the photobioreactor to operate at low hydraulic retention time and high organic loading rate. Therefore, the described flocculation behaviour during photo-hydrogen production is potentially suitable for practicable application.
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影响因子：
7.2
作者：
Gilbert, J. Jose;Ray, Subhabrata;Das, Debabrata
通讯作者：
Das, Debabrata
影响因子：
5.5
作者：
Kataoka, Y;Kondo, T
通讯作者：
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影响因子：
6.3
作者：
Abreu AA;Karakashev D;Angelidaki I;Sousa DZ;Alves MM
通讯作者：
Alves MM
影响因子：
3.3
作者：
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通讯作者：
Garidel, P
影响因子：
11.4
作者：
Jucker, BA;Zehnder, AJB;Harms, H
通讯作者：
Harms, H