Adenine nucleotide content and energy charge of Bacillus megaterium during batch growth in low-phosphate medium

Abstract The effect of a low phosphate concentration on intracellular adenine nucleotides, oxygen consumption and poly-β-hydroxybutyric acid synthesis, was investigated with batch cultures of Bacillus megaterium . At low phosphate concentrations the cells contained much larger amounts of poly-β-hydroxybutyric acid, but displayed lower adenylate energy charge and oxygen uptake than did control cells. The ratio of ATP to ADP was much greater in the control cells. The levels of ATP and AMP were lower in low-phosphate cells.     

Adenine nucleotide content and energy charge in dry cells and cysts of Azotobacter vinelandii

Abstract The levels of intracellular adenine nucleotides, energy charge, oxygen consumption and poly-β-hydroxybutyric acid stored, have been investigated in dry vegetative cells and cysts of Azotobacter vinelandii . The data show that under desiccation conditions the cysts retain viability at energy charge values of 0.20 and an ATP/ADP ratio of 0.24, whereas under the same desiccation conditions, vegetative cells die at energy charge values <0.5 and an ATP/ADP ratio of <0.6.     

Production of polyhydroxyalkanoates by Azotobacter chroococcum H23 in wastewater from olive oil mills (alpechin)

We describe the production of large amounts of homo- and copolymers of polyhydroxyalkanoates (PHAs) by Azotobacter chroococcum strain H23 when growing in culture media amended with alpechin. A. chroococcum grown on NH₄⁺-medium supplemented with alpechin formed PHAs up to 50% of the cell dry weight after 24h. The results show that alpechin supports the growth of strain H23 and also that this waste could be utilized as a carbon source. Production of PHAs by using alpechin looks promising, since the use of inexpensive feed-stocks for PHAs is essential if bioplastics are to become competitive products.     

Survival of Azotobacter spp. in Dry Soils

Dry soils stored in glass containers in the laboratory and protected from contamination for periods of 22 to 24 years yielded numerous colonies of Azotobacter chroococcum and other members of the family Azotobacteraceae. These results were compared with those reported in 1974, and the findings are uniformly consistent in terms of surviving populations. The data prove that these bacteria remain viable after prolonged periods of dormancy in much the same way as do the endospores of gram-positive bacteria.     

Adenine nucleotide content and energy charge of Azotobacter vinelandii during batch growth in dialysed-soil medium

Abstract In human peripheral blood, a factor which induces gonococcal resistance to complement-mediated killing by fresh human serum is more concentrated in the white blood cells of buffy coat than in red blood cells. Futhermore, the resistance-inducing factor is present in both polymorphonuclear phagocytes and mononuclear cells (monocytes and lymphocytes) separated from the buffy coat by centrifugation on Ficoll-Hypaque gradients. These results imply that inflammatory cells mobilised from the blood to sites of infection carry a host factor which, if it is available to the gonococci, would materially increase their ability to resist a major defence mechanism and hence enhance their capacity to maintain and increase infection.     

Flooding effects on abundance of an exploited,long-lived fish population in river-floodplains of the Amazon

Flooding regulates the amount and quality of habitat available for fish populations in river-floodplains. Although previous studies assessed fish population responses to river hydrology, the processes by which flooding affects fish abundance and catch remain unclear. Here, we investigated whether degree of flooding affects abundance and catch of Colossoma macropomum, a long-lived, overexploited fish population of the central Amazon Basin. We computed the degree of flooding corresponding to the feeding area of young-of-the-year C. macropomum as the annual magnitude of the moving littoral zone (ML). We estimated abundance of age classes one, two, and three of C. macropomum using a modeling program based on catch, fishing effort, and fish length frequency data from the principal commercial fishery. We found that flooding positively and non-linearly affected abundance of the age-one cohort but not of older age classes. ML data corresponding to a late rising water phase in which zooplankton, seeds, and fruits dominated the diet provided the strongest effect on age-one abundance. However, flooding effects on total catch were not found, likely due to catches comprising several age classes. These results provide support to existing evidence that the magnitude of the moving littoral zone regulates abundance of juvenile fish. Because the ML quantifies food and habitat availability for various other fish species, it may constitute an important control of fish abundance in these systems. Management of these fisheries may be improved by adjusting fishing effort based on hydrology. More generally, the information also serves to assess the impacts of hydrological alterations (e.g., dams) on fish recruitment.

     

Bactericidal effect of lactoferrin and lactoferrin chimera against halophilic Vibrio parahaemolyticus

Infections caused by Vibrio parahaemolyticus, an halophilic member of the genus Vibrio, have increased globally in the last 5 years. Diarrhea caused by V. parahaemolyticus results from eating raw or undercooked seafood. The aim of this work was to investigate whether lactoferrin and some lactoferrin-peptides have bactericidal activity against Vibrio parahaemolyticus ATCC 17802, the pandemic strain O3:K6, and the multidrug resistant isolate 727, as well as against Vibrio cholerae strains O1 and non-O1. Whereas both peptides lactoferricin (17-30) and lactoferrampin (265-284) did not have bactericidal activity, 40 microM of lactoferrin chimera (a fusion of the two peptides) inhibited the growth of all Vibrio tested to the same extent as the antibiotic gentamicin. The cidal effect of LFchimera showed a clear concentration response in contrast to bovine lactoferrin which showed higher inhibition at 10 microM than at 40 microM. FITC-labeled LFchimera bound to the bacterial membranes. Moreover LFchimera permeabilized bacterial cells and membranes were seriously damaged. Finally, in experiments with the multidrug resistant isolate 727, sub-lethal doses of LFchimera strongly reduced the concentrations of ampicillin, gentamicin or kanamicin needed to reach more than 95% growth inhibition, suggesting synergistic effects. These data indicate that LFchimera is a potential candidate to combat the multidrug resistant pathogenic Vibrio species.