Cell acinetobacter calcoaceticus

Hydroxylation of n-octane by cell extracts of Gordonia (Corynebacterium) sp. strain 7E1C (Cardini and Jurtshuk 1968), and of some strains of Acinetobacter calcoaceticus induced with -hexadecane (Asperger et al. 1981). 

This pathway is supported by the demonstration of benzyl alcohol dehydrogenase, benzaldehyde dehydrogenase, benzoyl-CoA ligase, and benzoyl-CoA reductase activities in cell extracts (Biegert and Fuchs 1995). The benzyl alcohol dehydrogenase from benzyl alcohol-grown cells was similar in many of its properties to those from the aerobic bacteria Acinetobacter calcoaceticus and Pseudomonas putida (Biegert et al. 1995). 

A well-studied example of a bioemulsifier is emulsan, a cell surface-exposed molecule that allows Acinetobacter calcoaceticus RAG-1 to attach to crude oil droplets [123]. Upon depletion of the short-chain alkanes utilised by this strain, the emulsan molecules were released from the bacterial surface, thereby allowing the cells to leave the oil droplet and to find a new substrate. Important positive side-effects of this mechanism seem to be that the remaining emulsan hydrophilises the droplet and prevents both the reattachment of A. calcoaceticus RAG-1 and the coalescence of the used oil droplet with other droplets that still contain unexploited alkanes. Bredholt et al. [124] studied the oil-emulsifying activity of Rhodococcus sp. strain 094. When exposed to inducers of crude-oil emulsification, the cells developed a strongly hydrophobic character, which was rapidly lost when crude-oil emulsification started. This indicated that the components responsible for the formation of cell-surface hydrophobi-city acted as emulsion stabilisers after release from the cells. 

The enantioselective reduction of the diketoester ethyl 3,5-dioxo-6-(benzyloxy) hexanoate (39) to the diol ethyl (31 ,5S)-dihydroxy-6-(benzyloxy)hexanoate (40a) has been demonstrated by Acinetobacter calcoaceticus SC 13876 in a yield of 85% with a diastereoselectivity of 97%. Cell extracts of A. calcoaceticus SC 13876 in the presence of NAD+, glucose, and glucose dehydrogenase reduced 39 to the corresponding isomeric monohydroxy compounds 42 and 43, which were further reduced to the compound 40a. A reaction yield of 92% and enantiomeric purity of 98% were obtained when the reaction was carried out at lOg/L in a 1-L batch (Patel et al., 1993). 

Ketoester Reduction Using Cell Extract of Acinetobacter calcoaceticus (E.C. 1.1.1.1) I30-321... 

Sedo and Zdrahal provide in Chap. 7 specific examples of MALDITOF MS profiling for successful differentiation between strains of the Lactobacillus acidophilus group and sqXqcXcA Mycobacterium spp. In these two examples, careful optimization of the culture protocols contributed to the method robustness. In addition, strains within the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. Staphylococcus aureus, and Bacillus subtilis ecotypes can be successfully typed by utilizing two alternative sample preparation protocols alternative MALDI matrix solution or microwave-assisted tiyptic digestion of the intact cells. 

Fig. 9 Dynamic kinetic resolution of benzyloxycyclopentanone catalyzed by whole cells harboring CHMO from Acinetobacter calcoaceticus NCIMB 9871 and Lewatit MP62 for racemization...

An enz3unatic process was developed for the reduction of a diketone, 3,5-dioxo-6-(benzyloxy) hexanoic acid, ethyl ester 105 to (3R,5S)-dihydroxy-6-(benzyloxy) hexanoic acid, ethyl ester 103 (Figure 4.29) by cells ot Acinetobacter calcoaceticus SC 13876 [133,134]. Both the si/n-4 and anti-8 dihydroxy esters were formed in the ratio of about 76 24 after 24h at lOg/1 of substrate 105 input. There was no significant peak due to a... 

Improvement of the stereoselectivity of the reaction was achieved when instead of benzoylformate decarboxylase from P. putida, the enzyme from A. calcoaceticus was used [92,93]. Acinetobacter calcoaceticus NCIB 8250 was grown in the medium described by Barrowman and co-workers [81,82], containing DL-mandelic acid, 3 g/L on an orbital shaker set at 200 rpm and 30°C for 16-20 h. The culture was serially transferred as a 10% inoculum through three further passages on the same medium under the same conditions. Cells recovered from the fourth passage were used in biotransformation experiments. 

Sar and Rosenberg 1983 reported that the majority of Acinetobacter strains produce extracellular nondialyzable emulsifiers. These strains included both soil and hospital isolates. Marin et al. 1996 have reported the isolation of a strain of A. calcoaceticus from contaminated heating oil that emulsifies that substrate. Neufeld and Zajic 1984 demonstrated that whole cells of A. calcoaceticus 2CA2 have the ability to act as emulsifiers, in addition to producing an extracellular emulsifier. 

Benzoylformate decarboxylase from Pseudomonas and Acinetobacter species, also an a-keto acid decarboxylase, has higher substrate specificity than pyruvate decarboxylase. Cells of these species grown in media inducing the mandelate pathway enzymes can convert benzoylformate and acetaldehyde to optically active 2-hydroxypropiophenone. Benzaldehyde is produced in this biotransformation reaction, as it is the normal product of benzoylformate decarboxylase. Some benzyl alcohol is also produced, in this case probably by reduction of benzaldehyde by cell oxidoreductases. In the case of P. putida the (S) enantiomer form of 2-hydrox) ropiophenone was produced, with an e.e. of 91-92%. The same product produced by A. calcoaceticus had an e.e. of 98%. An optimal volumetric production of 2-hydroxypropiophenone of 6.95 g per L per h was reported. 

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