Anaerobes cultivation

Amyloid beta (AP), 2283, 3712-3716, 3220 Amyloid plaques, 2283 Amyloid precursor protein (APP), 3714, 3715 Amyotrophic lateral sclerosis-Parkinsonism dementia, 41 Amyris, 722 Anabaena, 47, 58 A. circinalis, 59 A. crassa, 52 A. flos-aquae, 42, 52 A. lemmermannii, 52 Anabaseine, 1347 Anaerobic conditions, 1609 Anaerobic cultivation, 2443 Analgesic, 1389, 4119, 4122,4131, 4150 and anesthetic activities, 1508 effect, 4122... 

Lactic acid 120000 Biochemically by anaerobic cultivation of Bacillus and Lactobacillus spp. Polylactic acid used in the production of biodegradable polymers [3]... 

The fermentative production of butyric acid was first detected by Louis Pasteur from his landmark anaerobic cultivation in 1861 (Van Andel et al., 1985 Wu and Yang, 2003). The biochemical production of butyric acid using fermentation was popular in 1945 and onwards (Lee et al., 2008b). However, after 1960, this anaerobic fermentation lost its competitiveness due to high feedstock costs and fast-growing petrochemical industries. With increasing costs of liquid fossil fuels, rising environmental concerns, and the depletion of nonrenewable sources, interest has been reestablished in anaerobic fermentation. 

A bioreactor is a vessel in which an organism is cultivated and grown in a controlled manner to form the by-product. In some cases specialised organisms are cultivated to produce very specific products such as antibiotics. The laboratory scale of a bioreactor is in the range 2-100 litres, but in commercial processes or in large-scale operation this may be up to 100 m3.4,5 Initially the term fermenter was used to describe these vessels, but in strict teims fermentation is an anaerobic process whereas the major proportion of fermenter uses aerobic conditions. The term bioreactor has been introduced to describe fermentation vessels for growing the microorganisms under aerobic or anaerobic conditions. 

Cultivation of strictly anaerobic organisms requires not only that the medium be oxygen-free, but also that the redox potential of the medium be compatible with that required by the organisms. This may be accomplished by addition of reducing agents such as sulfide, dithionite, titanium(III) citrate, or titanium(IIl) nitrilotriacetate. Any of these may, however, be toxic so that only low concentrations should be employed. Attention has been drawn to the fact that titanium(III) citrate-reduced medium may be inhibitory to bacteria during initial isolation (Wachenheim and Hespell 1984). 

Hungate R E (1969) A roll tube method for cultivation of strict anaerobes. In Methods in Microbiology (Eds Norris and DW Ribbons), Vol 3B, pp 117-132. Academic Press, New York. 

Miller TL, MJ Wolin (1974) A serum bottle modification of the Hungate technique for cultivating obligate anaerobes. Appl Microbiol 27 985-987. 

Juarez-Rodriguez et al. applied the sludge derived from anaerobically digested cow manure in the production of biogas (methane-air), to maize (Zea mays L.) cultivated in a nutrient-low, alkaline-saline soil with EC 9.4 dS m 1 and pH of 9.3. The results showed that the C02... 

Juarez-Rodriguez J, Fernandez-Luqueno F, Conde E, Reyes-Varela V, Cervantes-San-tiago F, Botello-Alvarez E, et al. Greenhouse gas emissions from an alkaline saline soil cultivated with maize (Zea mays L.) and amended with anaerobically digested cow manure a greenhouse experiment. Journal of Plant Nutrition. 2012 35(4) 511-523. DOI 10.1080/01904167.2012.644371... 

A continuous centrifugal bioreactor, in which cells are fluidized in balance with centrifugal forces, has been designed to allow high density cell cultivation and superior aeration without elutriation of the suspended cells (van Wie et al., 1991). Reactor performance was hampered by elutriation of biomass by evolved gas in an anaerobic fermentation, indicating that it may not be suitable in its present state for three-phase fermentations. Immobilization of the cells on denser particles may overcome this problem. 

The assessment of the sustainability of the cultivation of energy crops includes the input and recycling of nutrients, the application of pesticides, the water-use efficiency, the consumption of fossil fuels and the balance of soil carbon. The aim is to recycle the nutrients, which is simple in the case of anaerobic digestion by applying the digestate to the field. If crops are combusted many of the minerals can be returned via the ash. In the case of liquid biofuels, exported nutrients are lost and have to be replaced. The application of pesticides, mainly herbicides, can often be reduced in comparison to food production, but the energy yield per hectare might be reduced if the share of weeds exceeds certain thresholds. Water use efficiency,... 

The uptake of heavy metals from soils is also determined by their contents in soil and by plant species. If these crops are used for anaerobic digestion one has to consider that there is a remarkable risk of an accumulation of heavy metals in soil. In the case of combustion, most heavy metals can be removed by filtering the ash and it can be used safely as fertiliser. Thus cultivation and combustion of short rotation coppice is a smart scheme of removing heavy metals from contaminated soils. 

We thus come to the remarkable conclusion that, beyond doubt, Leeuwenhoek in his experiment with the fully closed tube had cultivated and seen genuine anaerobic bacteria, which would happen again only after 200 years, namely, about 1862 by Pasteur. That Leeuwenhoek, one hundred years before the discovery of oxygen and the composition of air, was not aware of the meaning of his observations is understandable. But the fact that in the closed tube he observed an increased gas pressure caused by fermentative bacteria and in addition saw the bacteria, prove in any case that he not only was a good observer, but also was able to design an experiment from which a conclusion could be drawn. 

Under anaerobic conditions, various pathways exist for pyravate metabolism which serve to re-oxidize the reduced hydrogen carriers formed during glycolysis. The ultimate acceptor builds up as a waste product in the culture medium. The end-products of the pathways are (1) CO, ATP, and acetate (2) COj and ethanol (3) and CO2 (4) COj and 2,3-butylene glycol (5) COj, Hj, acetone, ATP, and butanol (6) succinate and (7) lactate. The pathway that occurs depends on the microorganism cultivated and the culture. 

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