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Effects of sodium chloride on n-caproate production from lactate and the mixed microbial comm unity*(PDF)

Chinese Journal of Applied & Environmental Biology[ISSN:1006-687X/CN:51-1482/Q]

2019 06
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Effects of sodium chloride on n-caproate production from lactate and the mixed microbial comm unity*
ZHENG Shaorui 1 2 ZHU Xiaoyu 2** ZHOU Lixiang 1 WANG Xinyu 2 & GU Ye 1
1College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
2Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
NaCl n-caproate lactate Clostridium IV mixed microbiome

This study explored effect of NaCl on n - caproate, medium chain carboxylate, production from lactate by Clostridium IV dominating mixed microbiome. The production and composition of fermentation products of lactate, and the microbial community were investigated at five different NaCl concentrations: 2, 6, 10, 20, and 30 g/L and at 0 g/L (control). The results showed that increasing of NaCl concentration (from 2 to 10 g/L) triggered the decrease of n-caproate production and shifted the conversion outcome from medium chain carboxylate (n-caproate) to rapid accumulation of short chain carboxylates (acetate, propionate, n-butyrate and n-valerate). NaCl concentration of 20 g/L dropped n-caproate concentration, resulting in a selective favorable to propionate, n-butyrate and n-valerate production. A further increase of NaCl concentration to 30 g/L caused propionate to be the occupied chemical, decreased cell density and activity (depending on ATP concentration) of mixed microbiome . Microbial community diversity analysis showed that , as NaCl concentration increased from 0 g/L to 10 g/L, the relative abundance of Clostridium IV in total reads dec reased from 47.78% to 35.06%. Meanwhile, another genus Pseudoramibacter which may relate to n- caproate production increased from 0.04% to 0.17%. When NaCl concentration increased to 30 g/L, t he relative abundance of propionate-producing associating bacteria, Propionibacterium, increased from 0.006% to 0.09%. In summary, NaCl is an adverse factor for reactor microbiome which producing n-caproate from lactate. When the concentration of NaCl is lower than 6 g/L, the reactor microbiome can still be able to produce n-caproate as dominating product from lactate; However, further increase of NaCl concentration will inhibit or cease n-caproate production from lactate.




Last Update: 2019-04-15