Actinomycetes were isolated from near-shore marine sediments and water at four different sites in Alexandria. Statistical analysis revealed that variation in temperature, pH, and dissolved phosphate were of insignificant values, but that variation in total nitrogen and organic matter were significant. The treatment of sediments and water samples by heat resulted in a selective reduction of the nonactinomycetal heterotrophic microflora. Four selective culture media were used for counting actinomycetes in marine water and sediments. The starch nitrate medium favored the growth of these microorganisms. The diversity and counts of actinomycetes varied with the seasonal variation, and the highest counts were detected in dry warm seasons. The numbers of this bacterial group in sediments exceeded by far their numbers in seawater. A positive correlation was found between population size and location. Actinomycetes were found in the highest numbers in the upper layers (0–20 cm depth). In a few cases, the counts of actinomycetes showed bimodal maxima 0–20 and 60–100 cm deep. Sediments were the best source of marine actinomycetes, and their distribution varied depending on the depth from which samples were collected. The ratio of actinomycetes to the total microflora ranged from 0.48 to 2.29, depending on location.
A fusion protein of hexa-histidine repeat (His) and glycosylphosphatidylinositol (GPI)-anchor region of Saccharomyces cerevisiae Cwp1 with Aspergillus oryzae Taka-amylase A (TAA) was expressed on the yeast cell surface. The expressed fusion protein (TAA-His-Cwp1) was localized on the cell wall and demonstrated amylolytic activity. In comparison with the TAA-Cwp1 expressing strain, these cells exhibited 1.6- to 2.8-fold higher adsorbing capacity for Cu2+, Ni2+, and Zn2+.
Fumarate-reducing bacteria were sought from the main ruminal bacteria. Fibrobacter succinogenes, Selenomonas ruminantium subsp. ruminantium, Selenomonas ruminantium subsp. lactilytica, and Veillonella parvula reduced fumarate by using H2 as an electron donor. Ruminococcus albus, Prevotella ruminicola, and Anaerovibrio lipolytica consumed fumarate, although they did not oxidize H2. Of these bacteria, V. parvula, two strains of Selenomonas, and F. succinogenes had a high capacity to reduce fumarate. In all the fumarate-reducing bacteria examined, fumarate reductase existed in the membrane fraction. Based on the activity per cell mass and the affinity of fumarate reductase to fumarate, these bacteria were divided into two groups, which corresponded to the capacity to use H2: A group of bacteria with higher activity and affinity were able to use H2 as an electron donor for fumarate reduction. The bacteria in this group should gain an advantage over the bacteria in another group in fumarate reduction in the rumen. Cellulose digestion by R. albus was improved by fumarate reduction by S. lactilytica as a result of an increased growth of R. albus, which may have been caused by the fact that S. lactilytica immediately consumed H2 produced by R. albus. Thus fumarate reduction may play an important role in keeping a low partial pressure of H2 in the rumen.
The growth of Escherichia coli was inhibited by ethylene glycol bis(beta-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) in a medium of initial pH 8.8. The growth inhibition was reversed by the addition of CaCl2. E. coli could grow in the presence of EGTA at pH values below 8. The concentration of free calcium ions increases with a decrease in medium pH because of a decrease in the calcium binding capacity of EGTA. So, although the results suggest that calcium ions are essential for the growth of E. coli, the minimum concentration required is very low.
Microbial community dynamics in a flowerpot-using solid biowaste composting (FUSBIC) process were monitored seasonally by quinone profiling and conventional microbiological methods. The FUSBIC system, which consisted of three flowerpots (14 L or 20 L capacity) with 5–6 kg each of a soil-compost mixture (SCM) as the primary reactors, was loaded daily with household biowaste from November 1998 to October 1999. The monthly average waste reduction rate was 88.2% for the 14-L system and 92.5% for the 20-L system on a wet weight basis. The direct total microbial count detected in the 14-L primary reactors ranged from 4.5 to 9.6×1011 cells·g−1 of dry wt of SCM, and the viable count of aerobic heterotrophic bacteria recovered on agar plates at 28°C varied from 1.9 to 5.7×1011 CFU·g−1 of dry wt. The quinone content of SCM samples from the 14-L and 20-L systems ranged from 160 to 353 nmol·g−1 of dry SCM. Ubiquinones, unsaturated menaquinones, and partially saturated menaquinones constituted 15.0–36.4, 14.8–22.0, and 41.8–61.6 mol% of the total content, respectively. The major quinone types detected were usually MK-8(H2), MK-9(H2), and Q-10. Variations in quinone profiles were evaluated numerically by using two parameters, the dissimilarity index (D) and microbial divergence index (MDq). The upper limit of seasonal changes in the microbial community structure was about 30% as expressed by D values. The MDq values calculated ranged from 18 to 22. A significant positive correlation was found between seasonal temperature and bacterial populations containing partially saturated menaquinones. These results indicated that the FUSBIC system contained highly diverse microbial populations that fluctuated to some extent depending on seasonal temperature. Members of the Actinobacteria were suggested to be the major constituents of the total population present.
Thirty-one Acetobacter strains obtained from culture collections and 45 Acetobacter strains isolated from Indonesian sources were investigated for their phenotypic characteristics, ubiquinone systems, DNA base compositions, and levels of DNA-DNA relatedness. Of 31 reference strains, six showed the presence of ubiquinone 10 (Q-10). These strains were eliminated from the genus Acetobacter. The other 25 reference strains and 45 Indonesian isolates were subjected to a systematic study and separated into 8 distinct groups on the basis of DNA-DNA relatedness. The known species, Acetobacter aceti, A. pasteurianus, and A. peroxydans are retained for three of these groups. New combinations, A. orleanensis (Henneberg 1906) comb. nov., A. lovaniensis (Frateur 1950) comb. nov., and A. estunensis (Carr 1958) comb. nov. are proposed for three other groups. Two new species, A. indonesiensis sp. nov. and A. tropicalis sp. nov. are proposed for the remaining two. No Indonesian isolates were identified as A. aceti, A. estunensis, and A. peroxydans. Phylogenetic analysis on the basis of 16S rDNA sequences was carried out for representative strains from each of the groups. This supported that the eight species belonged to the genus Acetobacter. Several strains previously assigned to the species of A. aceti and A. pasteurianus were scattered over the different species. It is evident that the value of DNA-DNA relatedness between strains comprising a new species should be determined for the establishment of the species. Thus current bacterial species without data of DNA-DNA relatedness should be reexamined for the stability of bacterial nomenclature.
The cystite formation of Arthrobacter ureafaciens NRIC 0157T was studied by the use of a newly designed CT medium composed of 2.0% D-glucose, 0.28% NH4H2PO4, 0.136% K2HPO4, 0.136% KH2PO4, 0.0005% MgSO4·7H2O, and 0.0007% CaCl2·2H2O. Cystites are drumstick-shaped and oval cells and are larger than vegetative cells. Cystites are Gram-negative, whereas vegetative cells are Gram-positive by the KOH reaction. The concentration and ratio of K+ and Mg2+ in CT medium mainly affected the cystite formation. Cystites are considered aberrant forms produced by nutritional imbalance.
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)