High production of alkaline protease by Bacillus licheniformis in a fed-batch fermentation using a synthetic mediumMao, Weiying; Pan, Renrui; Freedman, David
doi: 10.1007/BF01583724pmid: N/A
High production (9016 U/ml) of alkaline protease by Bacillus licheniformis has been achieved. A 49% increase in production was achieved by the method used as compared with a batch process. By using a synthetic medium and a fed-batch operation controlled by the Advanced Fermentation Software (AFS) package, it was found that the keys to high production of protease are: (i) to maintain a low concentration of glucose (<0.43 g/l) in the medium; (ii) to control pH at a certain level (pH 6.50) in the culture; and (iii) to use rough type colonies as the starting culture. Our fed-batch fermentation process successfully simulates and surpasses ordinary batch fermentation processes. By using ammonium sulfate instead of soy bean flour as the only nitrogen source, an expected benefit was the elimination of unpleasant odors caused by natural organic nitrogenous components in the media. This would improve the industrial production environment.
Localization of volatile acidity reducing factors in grapeDelfini, C.; Pessione, E.; Moruno, E.; Giunta, C.
doi: 10.1007/BF01583727pmid: N/A
Must clarification processes cause an increase in the acetate content of wine at the end of the alcoholic fermatation process, this phenomenon being particularly noticeable when fermentation is obtained by means of the so-called ‘high acetate-producer’ yeast strains. The influence of different must fractions (free run juice, pressed juice, skins and seeds) on acetate production in white grape was investigated, and the addition of skins and and seeds to a synthetic nutritive medium (MNS) was seen to cause a considerable reduction in acetate production. Strain-related differences become evident when the grape bunch is subjected to heat shock (90°C) before musting. In such conditions, acetate content after fermentation is approximately the same as that of the control specimen (not heat treated) for the low acetate-producer strain (S191c) and higher for the high producer strain (S22b). This suggests the presence of some thermolabile factor that is responsible for inhibiting acetate production. In order to determine the chemical nature of this factor, a series of tests was performed on two substances contained in grape skins and seeds, i.e., polyphenolic compounds and unsaturated fatty acids. A reduction in acetate production was observed in the presence of both substances, their effect being greater when used in connection with high acetate-producer yeast strains.
Enhanced production of d (−)-lactic acid by mutants of Lactobacillus delbrueckii ATCC 9649Demirci, Ali; Pometto, Anthony
doi: 10.1007/BF01583728pmid: N/A
Chemical mutagenesis with ethyl methanesulfonate (EMS) was used to develop strains of Lactobacillus delbrueckii (ATCC 9649) that tolerated increased lactic acid concentrations while continuously producing the acid. Three mutants (DP2, DP3 and DP4) were compared with wild-type L. delbrueckii by standing fermentations with different glucose concentrations. All three mutants produced higher levels of lactic acid than the wild-type. In pH-controlled (pH 6.0) stirred-tank-batch fermentations, mutant DP3 in 12% glucose, 1% yeast extract/mineral salt/oleic acid medium produced lactic acid at a rate that was more than 2-times faster than the wild-type. Mutant DP3 also produced 77 g/l lactic acid compared with 58 g/l for the wild-type. Overall, compated with wild-type, the mutants DP2 and DP3 exhibited faster specific growth rates, shorter lag phases, greater lactic acid yields, tolerated higher lactic acid concentrations, and produced as much as 12% lactic acid in 12% glucose, 3% yeast extract/mineral salt/oleic acid medium which required an additional 9% glucose when the residual glucose concentration decreased to ≤3%. Mutant DP3 was stable for over 1.5 years (stored freeze dried). The strain development procedure was very successful; mutants with enhanced lactic acid-producing capacity were obtained each time the procedure was employed.
Production of chiral epoxides by an ethene-utilising Micrococcus sp.Mahmoudian, Mahmoud; Michael, Ashour
doi: 10.1007/BF01583729pmid: N/A
An ethene-utilising bacterium was isolated in pure culture from soil and was tentatively identified as a Micrococcus sp. The organism accumulated epoxyalkanes (0.2–13 mM) from internal, terminal, cyclic and aryl-substituted olefins and exhibited a substrate specificity which was different from that expected on the basis of the chemical reactivity pattern in peracid epoxidations. Epoxyalkanes were hydrolysed at a much slower rate than the epoxidation step which allowed them to accumulate. Ethene-grown cells catalysed the stereospecific formation of R-1,2-epoxypropane (enantiomeric excess: e.e.=96%), R-1,2-epoxybutane (e.e.=94%) and trans -(2R,3R)-epoxybutane (e.e.=84%). An ethene monooxygenase was implicated in the production of chiral epoxides in cell-free extracts of the bacterium. The (2S,3S)-enantiomer of racemic trans -2,3-epoxybutane was stereoselectively hydrolysed to completion resulting in an enrichment in the (2R,3R)-enantiomer. Further hydrolysis of 1,2-epoxyalkanes (C 3 -C 4 ), however, occurred via complete destruction of both stereoisomers.
Inactivation of Salmonella enteritidis on shell eggs by novel N -halamine biocidal compoundsWorley, Brian; Wheatley, W.; Lauten, S.; Williams, D.; Mora, E.; Worley, S.
doi: 10.1007/BF01583730pmid: N/A
Several new N -halamine compounds have been evaluated as potential replacements for free chlorine as disinfectants for the egg-processing industry. The compounds were tested against Salmonella enteritidis on the surfaces of egg shells. Test procedure included spraying inoculated egg shells with solutions of several of the N -halamine compounds and free chlorine for comparison, suspending the most stable N -halamine compound in a thin coating of mineral oil on the egg shell and subsequent inoculation, and measuring the rates of diffusion of the compounds and free chlorine through the egg shells. Compounds DBC (1-bromo-3-chloro-2,2,5,5-tetramethylimidazolidin-4-one) and DC (1,3-dichloro-2,2,5,5,-tetramethylimidazolidin-4-one) were significantly more efficacious than free chlorine in inactivating Salmonella in the spray experiments, while compound MC (1-chloro-2,2,5,5-tetramethylmidazolidin-4-one), in a mineral oil suspension, provided disinfection of the egg shells within 72 h of contact. None of the disinfectant compounds penetrated egg shells at a rate greater than 1 mg/l over a period of 6 h. Compound MC is recommended as a possible replacement for unstable, corrosive-free chlorine as a bactericide for the egg-processing industry.
A new strain of Rhodotorula rubra isolated from yogurtHari, Ravinder; Patel, Thakor; Martin, Antonio
doi: 10.1007/BF01583731pmid: N/A
A new strain of Rhodotorula rubra has been isolated from yogurt which shows promise as a source for pigment and protein feed for aquacultured animals. The pigment was extracted by rupturing the cells with the French press followed by extraction with acetone and purification of the acetone extract using petroleum ether and cold 10% NaCl. The absorption spectrum indicated that the pigment was a carotenoid, the chemistry of which was examined using nuclear magnetic resonance, mass spectroscopy and resonance Raman spectroscopy. A reverse-phase HPLC equipped with octadecylsilylated (ODS) silica column showed nearly 80-times more pigment production under similar cultural conditions that Phaffia rhodozyma . The isolate grows optimally at 20°C when grown on a variety of media. Its morphology has been studied using transmission electron microscopy, scanning electron microscopy and phase contrast microscopy. From the results of the API system, the isolate was identified as Rhodotorula rubra .
Evaluation of a microbial method to reduce hydrogen sulfide levels in a porous rock biofilmMclnerney, Michael; Bhupathiraju, Vishvesh; Sublette, Kerry
doi: 10.1007/BF01583732pmid: N/A
The efficacy of nitrate addition, with and without inoculation with a sulfide-resistant strain of Thiobacillus denitrificans (strain F), in reducing sulfide levels in an experimental system using cores and subsurface formation water from a gas storage facility was examined. The addition of nitrate (40 mM) alone to the formation water injected into core systems operated at hydraulic retention times of 3.2 and 16.7 h resulted in lower effluent sulfide concentrations, from an influent concentration of about 170–190 μM to an effluent concentration of 110 and 3 μM, respectively. A reduction in effluent nitrate concentrations in both core systems indicated the presence of indigenous nitrate-using populations. After strain F was inoculated into the core system operated at the shorter retention time, the effluent sulfide concentration decreased from 110 to 16–25 μM. The effluent sulfate concentration increased, and the effluent nitrate concentration decreased concomitant with the presence of high concentrations of denitrifying thiobacilli in the inoculated core system. The denitrifying thiobacilli detected after inoculation were presumed to be strain F since these organisms were not detected in this core system before inoculation, or in any of the samples from the uninoculated core system. These data suggest that the efficacy of the nitrate treatment may depend on the residence times of the liquids in the core system, and that inoculation with strain F was required to reduce sulfide levels to <20 μM in the core system operated at a short hydraulic retention time.