Micro-aerophilic

Perego et al. (20) found that during the fermentation of hemicellu-lose hydrolysates by Candida shehatae, the addition of 50 mM acetone resulted in ethanol yields comparable with those obtained under micro-aerophilic conditions. Thus, the addition of 50 mM acetone to the culture... 

Campylobacterjejuni Gram-negative enteric spiral rod, micro-aerophilic Severe enteritis... 

Though the complete pathway to coenzyme 4 in the micro-aerophilic organism, Pr. shermanii, is not yet available, much is known and a brief comparison with the fully mapped route used in the aerobic Ps. denitrificans now follows. Micro-aerophihc means almost anaerobically and under these conditions Pr. shermanii biosynthesises cobyrinic acid 58, Scheme 18, and some of its amide derivatives. The nucleotide loop, however, is constructed only in the presence of oxygen [122]. 

Much is also known about the route from ALA to coenzyme B12 in the micro-aerophilic organism Pr. shermanii. Of those steps that have been studied so far, a substantial majority occur using either identical intermediates to those established in Ps. denitrificans or they involve the cobalt complexes of the same organic ligands. There are differences, however, in that cobalt is inserted far earlier on the pathway in Pr. shermanii and an interesting modified mechanism is used for the ring contraction in this micro-aerophilic system. 

First, we optimized incubation of probes and control. It was shown that the initial bacteria titer in probes and control should not exceed 104 cell/mL, otherwise for several strains, the inhibition of bacteria growth in probes with active antibiotics was not observed during the short incubation time. The volume of probes and control, 1 mL, was selected (48-well multidish). The lower volume, 0.2 mL, resulted in 5-fold higher concentration of antibiotic in the probes. The following duration of incubation was selected 5 h - for aerobic strains, 10 h - for anaerobic or micro aerophilic strains. 

Under the conditions selected, 184 probes comprising 33 aerobic and micro aerophilic clinical strains (5-7 antibiotics per strain) were examined both by optimized BA and DM or SDM. The following criteria for assessment of antibiotic susceptibility of pathogen using BA were determined (Table 1). 

The technique of membrane filtration is used whenever the nature of the product permits. The membrane is transferred to the growth medium, or the medium is transferred onto the membrane. Alternatively, the prepared sample is inoculated directly into the appropriate media. This method is only used when the product (e.g. some vaccines) cannot be dissolved or diluted in a nontoxic diluent. The media used are fluid thioglycolate medium (FTM) for aerobic, micro-aerophilic and anaerobic bacteria, and Soybean casein digest broth (SCDB) for aerobic bacteria and fungi. FTM and SCDB are incubated at 30-35 °C and 20-25 °C respectively, both for a period of not less than 14 days. This relatively long incubation period seems to be justified, because an unacceptable proportion of contaminants would be missed by limiting incubation to 7 days [60]. 

The urease produced by Helicobacter spp. is a neutral pH optimum enzyme [12] therefore, a fall of cytoplasmic pH is not an adaptive mechanism for this organism. The inhabitation of the gastric mucosa by Helicobacter such as H. pylori requires specialization of properties of this micro-aerophilic bacterial species in order to enable survival and growth on the gastric surface and within antral glands. It should be noted that there are also Helicobacter that do not inhabit the stomach, although why some of them have gastric adapted and some not is as yet unknown [13]. 

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