Effect of pH and retention time on volatile fatty acids production during mixed culture fermentation

<b>Inoculum concentration and inoculation time for propionic acid production from whey using mixed culture of <i>Lactobacillus helveticus</i> and <i>Propionibacterium freudenreichii</i> PS-1

“…Whey, the main by-product of the dairy industry, has aroused the interest of many researchers around the world because of its nutritional and functional capability (Jankowska, Chwiałkowska, Stodolny, & Oleskowicz-Popiel, 2015 and from 50 to 102 kg m -3 , respectively (Prazeres et al, 2012). Several studies have been conducted to develop new products in order to use whey, since the problem faced by the dairy industry worldwide is that only part of the whey produced is used, the rest is discarded as effluent because of the high cost and difficulty in processing it (Magalhães et al, 2011), despite its high nutritional value.…”

“…Toward this end, propionic acid-tolerant bacterial strains, reactors with immobilized cells, and reactors with recycling were developed to increase the productivity of fermentation (Feng et al, 2010, Zhu et al, 2012. Another study showed that mixed culture has a great chance of overcoming pure culture fermentations, making it an attractive process for the production of biochemicals compounds (Jankowska et al, 2015).…”

The effect of phosphate buffer on improving the performance of autothermal thermophilic aerobic digestion for sewage sludge

“…The effects of pH on anaerobic digestions have been investigated in many aspects, such as anaerobic digestions with different sources, [12][13][14] variant productions, [15][16][17] discrepant microbial communities 13,18,19 and so on. A few research works have also been done about the effect of pH on aerobic digestion, including aspects of nitrication, 20 biological phosphorus removal, 21 treatment efficiency, evolution of volatile fatty acids 22 and so on.…”

Biodigestão anaeróbia termofílica de vinhaça em sistemas combinados do tipo acidogênico-metanogênico para potencialização da recuperação de bioenergia em biorrefinarias de cana-de-açúcar de primeira geração

“…Embora na planta termoquímica a produção de etanol a partir do syngas seja convencionalmente conduzida a partir da síntese catalítica, estudos recentes abordam o emprego da fermentação do gás para tal fim (Show et al, 2012;Silva et al, 2014). Rotas solventogênicas são observadas normalmente em menores valores de pH (4,0-4,5), como um resposta do metabolismo microbiano ao acúmulo de ácidos no meio reacional (Antonopoulou et al, 2010), enquanto a proporção de AGVs também depende diretamente do tipo de substrato e das condições operacionais utilizadas nos biorreatores (Albuquerque et al, 2007;Xie et al, 2014;Jankowska et al, 2015;Sarma et al, 2015).…”

“…Ácidos orgânicos, tais como os ácidos acético, butírico e propiônico, podem ser utilizados diretamente em indústrias alimentícias e de síntese química (Leite et al, 2008;Jankowska et al, 2015;Sarma et al, 2015). Por sua vez, a produção de solventes como o etanol e butanol a partir de resíduos tende a aumentar diretamente o balanço energético em biorrefinarias (Xie et al, 2014 (Mariano et al, 2011).…”