Extracellular amino acids of aerobic spore-forming bacteria]

An ability to synthesize and accumulate in the growth medium for extracellular amino acids of 108 strains of 13 aerobic sporeforming bacteria species at deep cultivation on the simple synthetic glucose-mineral liquid nutrient medium optimized for the representatives of this genus. Has been studied the bacillus strains studied in the present conditions synthesize 19 amino acids and 2 amino carbons in different quantities and combinations. Amino acids being synthesized the most and least by these microorganisms have been determined in quantitative expression. Extracellular amino acid accumulation was proved to be a strain property not of genus. In general, the genus studied was evaluated as active one in amino acid production. The most active strains may present an interest as initials for further selective obtaining of producers of separate amino acids. The outlook for aerobic bacilli strains having marked amino-synthesizing properties and complex of other biological activities is being discussed for construction of medicinal and prophylactic of live microbial culture preparations.     

The formation of acetic acid from carbon dioxide and hydrogen by anaerobic spore-forming bacteria

Summary Further experiments on an anaerobic bacillus synthesising acetic acid from CO₂ and H₂ are described. The organism in question was classified asClostridium aceticum n.sp. Acetic acid is also formed from sugar.It was shown, that at any moment the number of H₂ molecules used for synthesis is proportional to the number of molecules present. Continuous provision with H₂ and CO₂ influences the rate of the process favourably. In such conditions a culture may absorb as much as 4.5 1 of H₂ a day at 30 C.The pH range ofCl. aceticum is between 7.5 and 10.5, the optimum being between 8 and 9.A growth promoting substance is present in alkaline mud extract. This substance can be concentrated by means of absorption or precipitation. Its nature is still unknown.     

Ecological characteristics of anaerobic ammonia oxidizing bacteria

Anaerobic ammonium oxidation (anammox) is the microbial conversion of ammonium and nitrite to dinitrogen gas. The functional microbes of anammox reaction are anammox bacteria, which were discovered in a wastewater treatment system for nitrogen removal. Anammox bacteria are prevalent in anoxic ecosystems and play an important role in both biological nitrogen cycle and nitrogen pollution control. In this paper, we reviewed the investigation on ecological characteristics of anammox bacteria, and tried to figure out their complicated intraspecies and interspecies relationships. As for intraspecies relationship, we focused on the quorum sensing system, a cell density-dependent phenomenon. As for interspecies relationship, we focused on the synergism and competition of anammox bacteria with other microorganisms for substrate and space. Finally, we discussed the great influence of environmental factors (e.g., dissolved oxygen, organic matters) on the constitution, structure and function of anammox bacteria community.     

Structural and physiological characteristics of some sheathed bacteria

The fine structure and growth of two gram-negative and two gram-positive strains of sheathed bacteria, isolated from activated sludge, have been studied. Their anatomy is quite different fromSphaerotilus natans. The cells are rectangular, tightly joined together, non-motile and enclosed by a sheath which is thin in the gram-negative strains and rather electron-dense in the two larger gram-positive strains. The four strains grow slowly and form pink filamentous flocs in liquid media.     

Growth and metabolism characteristics of anaerobic ammonium-oxidizing bacteria aggregates

The present study reported the growth and metabolism characteristics of anaerobic ammonium-oxidizing (anammox) bacteria aggregates in an expanded granular sludge bed (EGSB). The results showed that the anammox bacteria aggregates presented starvation, growth, and inhibition phase along with the increase of substrate supply. The substrate conversion rates for survival were 0.05 kgNH ₄ ⁺ –N/(kgVSS·day), 0.07 kgNO ₂ ^? –N/(kgVSS·day), and 0.12 kgN/(kgVSS·day); the substrate conversion rates for maximum growth were 0.21 kgNH ₄ ⁺ –N/(kgVSS·day), 0.24 kgNH ₄ ⁺ –N/(kgVSS·day), and 0.45 kgNH ₄ ⁺ –N/(kgVSS·day), respectively. In the growth phase, the yield of anammox bacteria aggregates was 0.14 gVSS/(gNH ₄ ⁺ –N), 0.12 gVSS/(gNO ₂ ^? –N), and 0.70 gVSS/(gNO ₃ ^? –N); the yield of extracellular polymeric substances (EPS) was 0.11 gEPS/(gNH ₄ ⁺ –N), 0.09 gEPS/(gNO ₂ ^? –N), and 0.55 gEPS/(gNO ₃ ^? –N), respectively. The EPS contents in anammox bacteria aggregates were high compared to that in anaerobic granular sludge. Speculated from the cell yield, the energy for anammox bacteria growth was not only from nitrite oxidation, but also from anammox reaction.     

Role of anaerobic spore-forming bacteria in the acidogenesis of glucose: Changes induced by discontinuous or low-rate feed supply

A mineral salts medium containing 1% (w/v) glucose providing carbon-limited growth conditions was subjected to anaerobic acidogenesis by mixed populations of bacteria in chemostat cultures. The formation of butyrate was shown to be dependent on the presence of saccharolytic anaerobic sporeformers in the acid-forming population. By the use of pasteurized activated sludge as an inoculum a culture was obtained consisting solely of anaerobic sporeformers that gave rise to the formation of butyrate, acetate, hydrogen and carbon dioxide as the main fermentation products. No formation of propionate could be detected. In this culture, the role of sporulation was investigated by applying periods of starvation and a single-step lowering of dilution rate (shift-down). In an experiment using a mineral salts medium supplemented with 1% (w/v) glucose and 0.5% (w/v) casein hydrolysate formation of refractile forespores as well as cell lysis could be demonstrated after 6 h starvation.In mixed cultures, initially inoculated with non-pasteurized activated sludge, a regular interruption of feed supply for 1 h per day resulted in selection of non-sporulatiog anaerobes. The fermentation pattern changed to a production of propionate and acetate, with a concomitant reduction of gas production. Similar results were obtained with shift-down in dilution rate.     

Correlation of DNA distribution and cytological differentiation of human cervical carcinomas

The DNA distribution of biopsy specimens from 46 patients suffering from cervical carcinoma was analysed by flow cytometry and compared with the cytological differentiation. According to morphological criteria the carcinomas were classified as highly differentiated, moderately differentiated and poorly differentiated. The results demonstrate that highly differentiated tumours contain hyperploid cells predominantly with hyperdiploid DNA content. Hyperploid cell populations in the moderately differentiated tumours are mainly in the hyperdiploid and tetraploid regions. Poorly differentiated tumours contain hypertetraploid and aneuploid cell populations. The significance of these findings is discussed.     

Non-sporulating anaerobic bacteria and anastomosis failure in patients with gastric carcinoma]

Cases of anastomosis suture failure within the period from 1977 to 1987 and from 1988 to 1998 in 139 patients after various surgical operations for gastric carcinoma were analyzed. Infection in the cases of the anastomosis sUture failure at the early terms was mainly due to representatives of Enterobacteriaceae and at the later terms the failure was mainly due to non-sporulating anaerobes belonging to Bacteroidaceae. The data are indicative of the fact that the use of antimicrobials requires a differential approach.     

Correlation between the physiological state of bacteria and the radioprotective effectiveness of cysteine

Summary E. coli 15 T^- cells were cultured in the presence of cysteine, then removed and subjected to X-ray irradiation in cysteine-free buffer. The radiation-sensitivity was then found to decrease in inverse ratio to the concentration of cysteine used. This phenomenon occurred only with log-phase cells, while the radiosensitivity of stat-phase bacteria remained unchanged.The biochemical background of this phenomenon was also studied by means of ³⁵S-Cysteine. The extent and distribution of cysteine incorporation into the fractions of log-phase cells were found to differ from those occurring in the fractions of statphase cells.The biochemical radioprotective effect of cysteine described above suggests two different explanations: a) the radioresistance induced by cysteine presupposes an active metabolic state of the cells, which may correlate with the induction of the repair systems; b) the cysteine incorporated by the cells provides a radio-protective effect; hence only the radiosensitivity of log-phase cells decreases, while that of the stationary phase cells remains unchanged owing to their inability to incorporate cysteine in an amount rendering them effective radioprotectors.     

Isolation and some characteristics of anaerobic oxalate-degrading bacteria from the rumen.

Obligately anaerobic oxalate-degrading bacteria were isolated from an enriched population of rumen bacteria in an oxalate-containing medium that had been depleted of other readily metabolized substrates. These organisms, which are the first reported anaerobic oxalate degraders isolated from the rumen, were gram negative, nonmotile rods. They grew in a medium containing sodium oxalate, yeast extract, cysteine, and minerals. The only substrate that supported growth was oxalate. Growth was directly related to the concentration of oxalate in the medium (1 to 111 mM), and cell yields were approximately 1.1 g (dry weight)/mol of oxalate degraded. Oxalate was stoichiometrically degraded to CO2 and formate. These anaerobes occupy a unique ecological niche and are distinct from any previously described oxalate-degrading bacteria.     

Biodiversity and physiological characteristics of Antarctic and Arctic lichens-associated bacteria

The diversity and physiological characteristics of culturable bacteria associated with lichens from different habitats of the Arctic and Antarctica were investigated. The 68 retrieved isolates could be grouped on the basis of their 16S rRNA gene sequences into 26 phylotypes affiliated with the phyla Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Firmicutes and with the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. Isolates belonging to the Alphaproteobacteria were the most abundant, followed by those belonging to Actinobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, and Deinococcus-Thermus. Phylogenetic analysis showed that approximately 21 % of the total isolates represented a potentially novel species or genus (≤97 % sequence similarity). Strains belonging to the genera Sphingomonas, Frondihabitans, Hymenobacter, and Burkholderia were recovered from lichen samples from both geographic locations, implying common and important bacterial functions within lichens. Extracellular protease activities were detected in six isolates, affiliated with Burkholderia, Frondihabitans, Hymenobacter, Pseudomonas, and Rhodanobacter. Extracellular lipase activities were detected in 37 isolates of the genera Burkholderia, Deinococcus, Frondihabitans, Pseudomonas, Rhodanobacter, Sphingomonas, and Subtercola. This is the first report on the culturable bacterial diversity present within lichens from Arctic and Antarctica and the isolates described herein are valuable resources to decode the functional and ecological roles of bacteria within lichens. In addition, the low similarity (≤97 %) of the recovered isolates to known species and their production of cold-active enzymes together suggest that lichens are noteworthy sources of novel bacterial strains for use in biotechnological applications.     

The DNA nucleotide composition of bacteria oxidizing diethylene glycols

Nucleotide composition of DNA has been analyzed in bacteria composing the diethylene glycol-oxidizing association. It is shown that the microorganisms under study are representatives of genera Alkaligenes and Achromobacter.