An experimental system has been devised for the optimum aerobic growth and induction of the halophilic aspartate aminotransferase of an archaebacterium Haloferax mediterranei incubated in the presence of L-aspartate. H. mediterranei utilizes both L-aspartate and yeast extract as a sole or combined energy source. The maximum synthesis of the enzyme was promoted by 1% L-aspartate. The relationship between holo and apo forms of the halophilic transaminase, as the mechanism of the induction system, seems to be related to unusual regulatory properties.
Internal cation concentrations of the halotolerant bacterium Brevibacterium sp. were investigated, with the cells grown in a complex media supplemented with nine kinds of salts. With increases in the external NaCl concentration, the amount of Na+ ion in the cells increased, while the intracellular concentration of the K+ ion remained almost constant (about 300mM). The same tendency was observed when NaCl was replaced with KCl, although the Na+ ion was very low (about 15mM). On the contrary, intracellular concentrations of Mg2+ and Ca2+ decreased slightly with the increase in NaCl or KCl concentrations in the medium. When the RbCl concentration in the medium was increased to more than 100mM, Rb+ ions in the cells increased about one hundred times, 550-600 mM, while K+ ions decreased to one-tenth. The same experiment was resumed using the chemically defined medium. We observed two different phenomena. First, the intracellular Na+ content (about 200mM) was more than ten-fold higher than that of the cells grown in the complex medium. Second, the release of K+ ions from the cells at alkaline pH was not as remarkable as that in the complex medium. The release of K+ ions observed in the complex medium was correlated with the addition of 50 mM diethanolamine-hydrochloride for adjusting medium pH at 9.0.
Megasphaera elsdenii was able to grow when the entracellular pH (Phe) was as low as, 5.5, and maintained a near-neutral intracellular pH (pHi) in the wide range of pHe. The membrane potential (Δφ) and Yglucose were decreased as the pHe was lowered from 6.7 to 5.5. When M. elsdenii was grown in the presence of 10mg/l monensin, 3% ethanol, or 25mM acetate, both Yglucose and pHi were decreased as the pHe declined. Acetate alleviated the growth inhibition by ethanol at low pHe. Unexpectedly, Δφ was increased remarkably by monensin or acetate only at pHe 6.0; this is inexplicable at present. Ethanol decreased the Δφ as the pHe was decreased.
A new anamorphic yeast species, Candida fragi Suzuki, Nakase et Fukazawa, is proposed for a strain isolated from fermenting strawberry that was formerly identified as C. sake, or C. natalensis. Candida fragi resembles C. natalensis. C. oleophila, and C. sake but is clearly differentiated from these species by DNA-DNA relatedness, electrophoretic enzyme patterns, and the proton magnetic resonance spectra of cell wall mannans. Practically, C. fragi is distinguished from C. natalensis by its inability to assimilate trehalose, mannoheptulose, and DL-glyceraldehyde; from C. sake by its inability to assimilate trehalose and α-methyl-D-glucoside and its ability to assimilate 5-ketogluconic acid and xylitol; and from C. oleophila by its inability to assimilate trehalose, to ferment galactose, and to grow in 100ppm of cycloheximide.
A slightly thermophilic hydrogen bacterium, "Pseudomonas hydrogenothermophila, " was found to contain 2-hydroxyputrescine, 2-hydroxyspermidine, diaminopropane, putrescine, cadaverine, spermidine, aminopropylcadaverine and spermine. A mesophilic hydrogen-oxidizing pseudomonad, "Pseudomonas hydrogenovora" contained putrescine, 2-hydroxyputrescine, and spermidine. The polyamine distribution pattern of the latter is rather common in the beta subclass of Proteobacteria. The occurrence of 2-hydroxyspermidine, aminopropylcadaverine and spermine is unique in the thermophile.
Nine castrated Japanese Saanen goats were used to investigate the effects of saturated fatty acids and their derivatives on the rumen ciliate protozoa. The goats were first fed a test diet composed of 500g of basal diet and 25g of one of the following: caprylic acid (C8), capric acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16) or stearic acid (C18). C10 proved to be the most toxic for the protozoa. Progressively less inhibition was displayed with either an increase or a decrease in the carbon chain length. Second, calcium (Ca) salts and triglycerides (TG) of C8 and C10 were applied. With the feeding of C10Ca or C10TG, the protozoa in the rumen disappeared. The toxic effects of free fatty acids were not alleviated by the derivatives. Third, protozoa other than Epidinium in a mixed-faunated goat disappeared after the feeding of hydrated coconut oil (52% lauric acid). Capric acid and its derivatives are considered useful rumen-defaunating agents. Lauric acid and its derivatives might be used to establish Epidinium mono-faunated animals.
The fractionation of bioflocculant FIX produced by Nocardia amarae YK1 revealed that the flocculant was a mixture of more than three substances. Although individual fractions did not exhibit the ability of flocculation at pH 5 to 7, synergetic flocculation was observed at pH 7 after mixing the fractions. Infrared spectrophotometry suggested that the chief components of fractions might be peptides. Enzymatic digestion of peptide moiety resulted in disappearance of flocculation activity. One of the ingredients of FIX carried high contents of glycine (25.6%), alanine (13.8%), and serine (12.3%), of which R groups were relatively small.
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Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)