Basal medium

In more recent times chemically defined basal media have been elaborated, on which the growth of various lactic acid bacteria is luxuriant and acid production is near-optimal. The proportions of the nutrients in the basal media have been determined which induce maximum sensitivity of the organisms for the test substance and minimize the stimulatory or inhibitory action of other nutrilites introduced with the test sample. Assay conditions have been provided which permit the attainment of satisfactory precision and accuracy in the determination of amino acids. Experimental techniques have been provided which facilitate the microbiological determination of amino acids. On the whole, microbiological procedures now available for the determination of all the amino acids except hydroxy-proline are convenient, reasonably accurate, and applicable to the assay of purified proteins, food, blood, urine, plant products, and other types of biological materials. On the other hand, it is improbable that any microbiological procedure approaches perfection and it is to be expected that old methods will be improved and new ones proposed by the many investigators interested in this problem. 

Antibiotic activities are examined by transfer of seed culture of Bacillus subtilis on nutrient agar on a Petri dish. The seed culture for Bacillus subtilis is a simple basal media of... 

The choice of appropriate basal media is of cardinal importance and a number of important practical considerations should be taken into account. 

Mineral-basal media may be sterilized by autoclaving, but for almost all organic compounds that are used as sources of C, N, S, or P, it is probably better to prepare concentrated stock solutions and sterilize these by filtration, generally using 0.2 pm cellulose nitrate or cellulose acetate filters. The same applies to solutions of vitamins, and to solutions of bicarbonate and sulfide that are components of many media used for anaerobic bacteria. 

Although organic substrates such as carboxylic acids are thermally stable and may be sterilized with the basal media, many others including, for example, carbohydrates, esters, or amides are better prepared as concentrated stock solutions, sterilized by filtration through 0.22 pm filters and added to the sterile basal medium. 

Table 2.2 Recommended values of NaHC03 in the liquid phase and C02 concentration in the gas phase to be employed with traditional basal media...

Medium composition is one of the most important factors in the culture of animal cells. Its function is to provide appropriate pH and osmolality for cell survival and multiplication, as well as to supply all chemical substances required by the cells that they are unable to synthesize themselves. Some of these substances can be provided by a culture medium consisting of low molecular weight compounds, known as basal media. However, most basal media fail to promote successful cell growth by themselves and require supplementation with more complex and chemically undefined additives such as blood serum. 

Media frequently employed in the culture of continuous mammalian cell lines include Eagle s medium, MEM (Eagle, 1959) Eagle s medium modified by Dulbecco, DMEM (Dulbecco and Freeman, 1959) RPMI 1640 medium (Moore et ah, 1967) CMRL 1066 medium (Parker et al., 1957) and Ham s F12 medium (Ham, 1965). For the cultivation of adherent continuous cell lines the following basal media are suitable CMRL 1066, MCDB 411, DMEM. F12, MCDB 301, and IMDM. For non-transformed cells, the media DMEM, IMDM, MCDB 104, 105, 202, 401, and 501 are suitable (Freshney, 1992). Each of these basal formulations may be supplemented with serum or other specific proteins. 

For insect cells the following basal media can be used Grace s, TC 100, TNM-FH, D22, Schneider, and M3. These media normally require supplementation with fetal bovine serum. Alternatively, different serum-free media are available for insect cells, such as Sf900II, Ex-Cell 400, 405, and 420, Express Five SFM, Insect-XPRESS , HyQ SFX-Insect , and IPL 41. These have the advantage of higher reproducibility and lower cost when compared with serum-supplemented basal media (Ikonomou et al., 2003). 

Synthetic method 26 A variety of growth factors is added to the existing basal media to replace the serum s functions. 

Figure 21 Relationship of Fe(III)-reducing bacteria activity and growth to oxide surface area, (a) Percent Fe(III) reduced as a function of oxide surface area. Surface area corresponded to different mineral types and included hematite, goethite, and ferrihydrite. (b) The density of Shewanella oneidensis cells as a function of the amount of structural Fe(III) reduction to Fe(It) in smectite clay, a strongly crystalline, high-surface-area Fe mineral. Differences in Fe(II) content reflect different amounts of clay particles inoculated into a minimal basal media (after Roden and Zachara, 1996 and Kostka et al, 2002a, respectively).

Table 2. Effects of phytohormones and basal media on shoot multiplication of C. ipecacuanha after 8 weeks of culturing at 25 °C under 16 hr/day light (80 pEm S" )...

Table 8. Influence of basal media on shoot formation on intemodal segments...

Although the emetine and the cephaeline could be detected in the first passage calli, they were undetectable by the third passage (section 2.1). However, root culture, especially root culture in liquid medium, showed consistent levels of alkaloids even after the third culture passage. In order to increase the yield of the alkaloids in root culture, culture conditions, such as various ph5dohormones and basal media were investigated [15, 54]. 

The effects of basal media on the alkaloid production in ipecac root cultures... 

The effects of MS, B5 and WP liquid basal media combined with IAA or NAA on the growth and alkaloid yields are shown in Fig. (32). In spite of auxin conditions, the roots in B5 medium produced less alkaloids than those in MS or WP medium. The best growth and alkaloid yields were obtained in MS medium in the presence of 5 mg/1 NAA. 

Fig. (32). Effects of MS, B5 and WP basal media combined with lAA or NAA on the growth and alkaloid yields (mg/1).

Fig. (41). Effects of basal media on the growth and the alkaloid yield in the hairy roots of Duboisia hybrid. The hairy roots (ca. 30 mg fresh weight) were inoculated into various basal liquid medium and cultured at 25 °C in the dark for 5 weeks. Bars represent standard deviation of the mean, n=3. Numbers in brackets show growth index on a dry weight basis. Growth Index = final dry weight / initial dry weight...

Table 22. Influences of temperature and basal media on the growth and alkaloid contents.

Hum F-12,[ 2] DM-160 and DM-170, etcJ l The MIT groupf 1 created the High-GEM (High Growth Enhancement Medium) in which fhictose replaces glucose as the energy source to achieve a 3- to 4-fold decrease in the accumulation of lactic acid. These basal media are now commercially available. 

A plethora of basal media for the growth of freshwater organisms has been formulated and these may differ significantly, particularly in the concentrations of phosphate, while for anaerobic bacteria the inclusion of bicarbonate and a suitable reductant is standard practice. Numerous examples of suitable media have been collected in The Prokaryotes (Balows et al. 1992). Clearly, if the... 

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