Rhizobium strains and cultivars of lentil (Lens culinaris) tolerant to soil acidity factors (high Al, Mn, and low pH, Ca and Mo) were selected and their interaction response was studied for nodulation, nitrogenase activity and grain yield in acid soils supplemented with AlCl3 and MnCl2. The symbiotic development of plant was affected by low pH but more markedly by higher concentrations of Al and Mn. The content and concentrations of root exudates of acid-tolerant or sensitive cultivars were different and chemotaxis to sugars, amino acids, organic acids and root exudates were strain specific. Acid-tolerant Rhizobium strains showed higher rates of oxidation of carbohydrates and tricarboxylic acid intermediates than sensitive strains.
Filamentous, non-heterocystous diazotrophic cyanobacterium Plectonemaboryanum simultaneously photoproduced hydrogen (0.30μmol mg-1 dry wth-1) and ammonium (8.2nmol mg-1 dry wth-1) under microaerobic (A:CO2, 96:4, v/v) conditions in the presence of 1mM sulfide. Nitrogen in the gas phase (A:CO2:N2, 72:4:24, v/v) enhanced the process more than two fold. A glutamine synthetase inhibitor, MSX, stimulated ammonium excretion and H2-production and pulses of MSX rather than a single dose favoured both the processes. A higher dose (15μM) in comparison to lower dose (5μM) of MSX, although it stimulated H2-evolution and NH4+-excretion, shortened the duration of both the processes. The stability of both the processes was prolonged in alginate-immobilized cyanobacterial cells besides enhancement in H2-evolution and NH4+-excretion. MSX was less toxic under immobilized state than the free cells.
Activities of enzymes of glyoxylate bypass, isocitrate lyase (ICL) and malate synthase (MS), were assayed in strains of Rhizobium and Bradyrhizobium grown on different carbon sources. In Rhizobium, ICL activity was detected in presence of either acetate or glycerol. In contrast, the enzyme was absent in glycerol-grown cells of Bradyrhizobium. MS was found to be constitutive in nature. Succinate allowed highest observed rate of growth and caused reduction of ICL activity when added to cells of Rhizobium sp. (Cicer arietinum) BICC 620 growing on acetate. Addition of cAMP substantially relieved succinate-mediated catabolite repression of ICL activity.
A lipolytic Pseudomonas sp. has been successfully immobilized in strontium alginate gel bead for use in the production of lipase. This paper reports on the various conditions required for its optimum production. A 3% alginate gel concentration with a 20% (w/v) cell loading gives the highest production of lipase. The production of lipase can be enhanced by aeration and shaking but mass transfer effect may be dependent on the ratio of cell mass and bead size. Prolonged recycling with aeration accelerates the rupturing of the beads compared to non-aerated system. A maximum production of lipase is given by 1.5g of immobilized bacteria in 50ml of culture broth. The immobilized bacteria can withstand recycling up to 24 days, (72h cycle), after which time the beads ruptured. The production, however, remains at 70%.
The aerobic bacteria, Erythrobacter longus and Roseobacter denitrificans, were examined for the effects of 5-aminolevulinate (ALA) and N-methylprotoporphyrin dimethyl ester (NMPD) on bacteriochlorophyll (Bchl) synthesis. Although external ALA seemed to be incorporated into a tetrapyrrole synthetic pathway leading to Bchl synthesis, there was no increase of Bchl in either Ro. Denitrificans or E. longus. With the addition of ALA, increased was protoporphyrin IX in Ro. Denitrificans, or protoheme in E. longus. NMPD enhanced the Bchl synthesis in E. longus but not in Ro. Denitrificans. It is likely that E. longus and Ro. Denitrificans are different from each other in the regulatory mechanism of Bchl synthesis.
Sequential colonization by various kinds of microbial populations in the rumen of calves was investigated. Four calves were fed with colostrum for 3 days and thereafter fed with 4l of cow's milk daily until 4 weeks of age. They had access ad libitum to a good quality hay from 10 days of age and to a concentrate from 2 weeks of age. The rumen was rapidly colonized by microbes immediately after the birth of the animals. The first bacteria which developed most abundantly in the rumen were Escherichiacoli and streptococci. The numbers of E. coli, which were high in 1-day-old calves, decreased gradually to reach a constant level within 6-8 weeks of age. The numbers of streptococci, which were high during 8 weeks after birth, decreased in a 10-week-old calf. The numbers of lactobacilli, which were high in a 1-day-old calf, increased in a 2-week-old calf, and thereafter remained constant. Amylolytic bacteria were present abundantly in 1-day-old calves. The numbers which increased in 3-day-old animals remained constant thereafter. The numbers of sulfate-reducers, lactate-utilizers, xylan-fermenters and pectin-fermenters which were low in 1-day-old calves, increased within 3 days after birth, and thereafter the levels remained constant. The cellulolytic bacteria which began to appear in animals 3-5 days of age, became abundant in calves 2-3 weeks old. The methanogenic bacteria which were present in calves 1-2 weeks of age became abundant when the animals were approximately 3 weeks old. The abundant appearance of sulfate-reducers, xylan-fermenters and pectin-fermenters in 3-day-old calves was new observation. The constitution of the anaerobic bacterial population in generic level in the rumen of a calf changed with age after birth. The constitution of predominant bacteria in the rumen of a calf at both 1 day old and 10 weeks old was similar to that of mature cattle. The composition of volatile fatty acids (VFA) in the rumen contents of calves changed with age after birth. The colonization by protozoa was observed in 8- to 10-week-old calves. Also, the importance of microbial interaction in the colonization by microorganisms in the rumen of calves is discussed in this report.
Wild-type and cytochrome-deficient strains of Schwanniomyces castellii were cultivated aerobically on citrate, and the effects of respiratory inhibitors on respiration, ATP levels and energy charge were measured. The obtained results demonstrate that every respiratory pathway of Schwanniomyces castellii involves phosphorylation site I, and suggest that the functioning of this site allows the alternative pathways to produce ATP.
Seventeen strains of Cytophaga, Flavobacterium and Actinobacillus species were taxonomically characterized. DNA base composition of these strains ranged from 39.0 to 42.3mol%, and the menaquinone system was MK-7. All the strains contained sphingolipids with long-chain bases, which are characteristic of the genus Sphingobacterium. Based on their chemotaxonomic and physiological characteristics together with DNA/DNA hybridization studies, we propose two new species and two new combinations, Sphingobacterium faecium sp. nov., Sphingobacterium piscium sp. nov., Sphingobacterium heparinum comb. nov., Sphingobacteriumthalpophilum comb. nov. and two genospecies of the genus Sphingobacterium. Flavobacterium yabuuchiae was found to be a synonym of Sphingobacterium spiritivorum.
The bacterial screening to get the strains that produce isomaltulose (palatinose, 6-O-α-D-glucopyranosyl-D-fructose) and trehalulose (1-O-α-D-glucopyranosyl-D-fructose) from sucrose, were carried out in Thailand. Many samples such as soil, fruits, etc., were obtained mainly from the northeastern area of Thailand. And several strains named MX-2, -4, -10, -11, and -13 were isolated from these samples. These strains, which were facultative anaerobic, gram-negative and rod-shaped bacteria, belonged to the genus Klebsiella: K. planticola (MX-2, -4, -10, and -11), and K. terrigena (MX-13) The strain MX-10 produced isomaltulose and trehalulose from sucrose, and the yields of isomaltulose and trehalulose were 65 and 30% as against sucrose, respectively, when 98% of sucrose was transformed. It is interesting that the trehalulose yields were higher in the reactions by the strain MX-10 than those by Protaminobacter rubrum (9% of trehalulose and 86% of isomaltulose). The results obtained by using immobilized cells of MX-10 were described.
The distribution of wild yeasts was studied in 11 samples of grape varieties at 5 localities of different climatic conditions of Nagano and Yamanashi Prefectures in Central Japan. The yeast populations in 6 healthy samples ranged from 0.007 to 6.0×103CFU/ml. In five samples of slightly injured grapes, populations were 110 to 1, 100×103CFU/ml. Two hundred and sixty eight isolates were assigned to 12 species belonging to 4 genera. In 6 samples of grape varieties, Kloeckera apiculata predominated. In contrast, in the other 5 samples of 3 grape varieties, basidiomycetous yeasts (Cryptococcus, Rhodotorula, and other genera) predominated. Generally, basidiomycetous yeasts predominated in a late crop varieties from chilly climatic regions, and ascomycetous yeasts (K. apiculata) predominated in grape varieties from mild climate regions.