Dhillon G S, Brar S K, Verma M, Tyagi R D
INRS-ETE, Université du Québec, Québec City, QC, Canada Institut de recherche et de développement en agroenvironnement inc. (IRDA), Québec City, QC, Canada.
J Appl Microbiol. 2011 Apr;110(4):1045-55. doi: 10.1111/j.1365-2672.2011.04962.x. Epub 2011 Feb 23.
To evaluate the potential of apple pomace (AP) supplemented with rice husk for hyper citric acid production through solid-state fermentation by Aspergillus niger NRRL-567. Optimization of two key parameters, such as moisture content and inducer (ethanol and methanol) concentration was carried out by response surface methodology.
In this study, the effect of two crucial process parameters for solid-state citric acid fermentation by A. niger using AP waste supplemented with rice husk were thoroughly investigated in Erlenmeyer flasks through response surface methodology. Moisture and methanol had significant positive effect on citric acid production by A. niger grown on AP (P < 0·05). Higher values of citric acid on AP by A. niger (342·41gkg(-1) and 248·42gkg(-1) dry substrate) were obtained with 75% (v/w) moisture along with two inducers [3% (v/w) methanol and 3% (v/w) ethanol] with fermentation efficiency of 93·90% and 66·42%, respectively depending upon the total carbon utilized after 144h of incubation period. With the same optimized parameters, conventional tray fermentation was conducted. The citric acid concentration of 187·96gkg(-1) dry substrate with 3% (v/w) ethanol and 303·34gkg(-1) dry substrate with 3% (v/w) methanol were achieved representing fermentation efficiency of 50·80% and 82·89% in tray fermentation depending upon carbon utilization after 120h of incubation period.
Apple pomace proved to be the promising substrate for the hyper production of citric acid through solid-state tray fermentation, which is an economical technique and does not require any sophisticated instrumentation.
The study established that the utilization of agro-industrial wastes have positive repercussions on the economy and will help to meet the increasing demands of citric acid and moreover will help to alleviate the environmental problems resulting from the disposal of agro-industrial wastes.
评估添加稻壳的苹果渣（AP）通过黑曲霉NRRL - 567固态发酵生产高柠檬酸的潜力。采用响应面法对水分含量和诱导剂（乙醇和甲醇）浓度这两个关键参数进行优化。
本研究通过响应面法在锥形瓶中深入研究了使用添加稻壳的AP废料进行黑曲霉固态柠檬酸发酵的两个关键工艺参数的影响。水分和甲醇对生长在AP上的黑曲霉产柠檬酸有显著的正向影响（P < 0.05）。黑曲霉在AP上产柠檬酸的较高值（干底物分别为342.41gkg⁻¹和248.42gkg⁻¹）是在75%（v/w）水分以及两种诱导剂[3%（v/w）甲醇和3%（v/w）乙醇]条件下获得的，根据144小时培养期后利用的总碳量，发酵效率分别为93.90%和66.42%。采用相同的优化参数进行传统托盘发酵。在托盘发酵中，分别获得了187.96gkg⁻¹干底物（含3%（v/w）乙醇）和303.34gkg⁻¹干底物（含3%（v/w）甲醇）的柠檬酸浓度，根据120小时培养期后的碳利用情况，发酵效率分别为50.80%和82.89%。
苹果渣被证明是通过固态托盘发酵高产柠檬酸的有前景的底物，这是一种经济的技术，不需要任何复杂的仪器设备。
该研究表明，利用农业工业废料对经济有积极影响，将有助于满足对柠檬酸不断增长的需求，而且有助于缓解因农业工业废料处理而产生的环境问题。
