Microbiology of fermentation

Although an extremely small population of LAB is present, it is assumed that plants are the natural habitat for some species. According to Daeschel et ah, 1987, certain species are always to be found, namely  

It seems that these organisms belong mainly to those that use the so-called Mn(II) mechanism, to protect themselves against toxic O2 radicals. The Mn(II) mechanism means that these organisms are capable of intracellular Mn2+ accumulation in order to neutralize endogenous 02 radicals according to the formula  

Since this mechanism has only been found in LAB, one may speculate that plants 

Typical of the microbial succession in sauerkraut fermentation, the so-called betabacteria (heterofermentative lactobacilli such as Lb. brevis with higher acid and salt-tolerance than L. mesenteroides) will gradually dominate the population accompanied by a reduction in viable Leuconostoc numbers. The length of the first two stages of sauerkraut fermentation is determined by the temperature, but typically ranges from 3 to 6 days, and is associated with an increase in lactic acid up to around 1% (Muller, 1988). 

Consumers preferences in Europe for milder (acid and salt) have prompted the un-packaging and pasteurization of sauerkraut upon reaching a pH of 3.8-4.1. 

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Source Adams, M.R. Microbiology of Fermented Food, pp. 1 4. London Blackie Academic and Professional, 1998. ... 

Baldensperger J, Le Mer J, Hannibal L, Quinto PJ (1985) Biotechnol Lett 7 743 Yokotsuka T (1985) In Wood BJB (ed) Microbiology of fermented foods. Elsevier Applied Science, London, pp 197-249... 

Grosch, W. and Schieberle, P. 1997. Flavor of cereal products—a review. Cereal Chem. 74, 91-97. Hammes, W.P. 1990. Bacterial starter cultures in food production. Food Biotechnol. 4, 383-397. Hammes, W.P. and Ganzle, M.G. 1998. Sourdough breads and related products. In Microbiology of Fermented Foods (B.J.B. Wood, ed.), 2nd Ed., Vol. 2, pp. 199-216. Blackie Academic Professional, London. 

Wood BJB (1985) Microbiology of Fermented Foods. Elsevier, London... 

Eowler, M.S., Leheup, P. and Cordier, J.L. (1998) Cocoa, coffee and tea. In Microbiology of Fermented Foods ((ed.) B.J.B. Wood), vol. 1, Blackie Academic and Professional, London, United Kingdom. 

Some of the other research studies have addressed topics such as high soHds biomass digestion (154), utilization of superthermophilic organisms (155), advanced reactor designs (156), landfill gas enhancement (157), and microbiology of the mixed cultures involved in methane fermentation (158). 

Actinomycetes Large surface area to volume ratio should favour protein export Widely used in industrial microbiology Good expression systems being developed Promoters/gene regulation still poorly understood Rheology of fermentations important... 

The presence of S. mutans and other cariogenic bacteria contributes towards the formation of a biofilm known as dental plaque, and their metabolism of fermentable carbohydrates in the diet leads to the formation of acids [12]. Dental caries has been described as a complex imbalance in physiologic equilibrium between tooth mineral and biofilm [13]. Biofilms imply the involvement of microbiological species [14], but the key concept included within this definition is that the bacteria involved are native to the body, not a group of specific invasive bacteria causing infection [14]. 

Table 10.1 gives a summary of the main by-products of fermentation by yeasts and other microbiological activities which can be identified in distilled spirits from different raw materials, like fruits, wine, grain, sugar cane, or other carbohydrate-containing plants. Since the sensory relevance of a flavour compound is related to its odour thresholds and odour quality. Table 10.1 presents also odour qualities and a review of threshold values of the fermentation by-products in ethanol solutions [9-10] and/or water [11-14] (Christoph and Bauer-Christoph 2006, unpublished results). 

Marshall, V.M.E. and Tamime, A.Y. (1997) Physiology and biochemistry of fermented milks, in Microbiology and Biochemistry of Cheese and Fermented Milk, 2nd edn (ed. B.A. Law), Blackie Academic Professional, London, pp. 153-92. 

Acknowledgements. This work was carried out in the laboratory of Fermentation Physiology and Applied Microbiology, Department of Agricultural Chemistry, Kyoto University. We greatly appreciate the efforts of all members of the laboratory and its collaborators. In particular, we are deeply indebted to Emeritus Prof. Hideaki Yamada of Kyoto University, a former professor of this laboratory and a pioneer of screening for novel microbial enzymes, for his valuable discussion and encouragement. 

The fermentation batches are incubated aerobically under stirring at 28°-30°C. At intervals the antibiotic activity is assayed microbiologically by the agar diffusion method using Sarcina lutea as the test organism. The maximum activity is reached after 96-120 h of fermentation. 

There exist countless publications about the general as well as specific culture conditions of bacteria and, in particular, actinomycetes used to produce secondary metabolites. One of the best introductions to the field of fermentation is provided by the Manual of Industrial Microbiology and Biotechnology published in 1999 with Demain and Davies as the editors in chief.68 Countless scientific publications, e.g. The Journal of Antibiotics, give excellent additional information on the subject, but it should be noted that industrial processes for high-value products are usually not published in detail and are kept as company intellectual property or trade secrets. 

Beltran, G., Novo, M., Guillamon, J. M., Mas, A., Rozes, N. (2008) Effect of fermentation temperature and culture media on the yeast lipid composition and wine volatile compounds. International Journal of Food Microbiology, 121, 169-177. 

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