The effects of fungicides on the microbiology and biochemistry of soils

A study was made of the effects of a wide range of modern fungicides on the microbiology and biochemistry of soils. The addition of fungicides to laboratory incubated soils led to marked changes in the soil microbial equilibrium. Initially fungal potential was decreased, but soon recovered to exceed that of the control at the end of 28 days. Bacterial numbers on the other hand increased dramatically following treatment. Similar changes were seen in field soils which had been treated with fungicides. The response of the cellulolytic fungal flora to field treatment with fungicides was also studied. Changes in the pattern of recolonization occurred, with species such as T. koningii, and P. nigricans becoming dominant. Cellulolytic fungi were largely insensitive to the addition of fungicides to their growth medium. Marked changes in the mineralization of nitrogen followed fungicide treatment. In the field all the fungicides used inhibited nitrification to a greater or lesser extent while levels of the ammonium ion were increased. Similar changes were seen in laboratory incubated soils. Here treatment with high concentrations of fungicides led to nitrification-inhibition while an increase in nitrate production often followed treatment with low concentrations. The amounts of ammonium-N in these soils increased dramatically following treatment. Towards the end of the incubation period (28 days) low concentrations of fungicides led to increases in the total free amino-acid-N content in soil, while the converse was true of high concentrations. Addition of fungicides also led to qualitative changes in the free amino acid content of soils. Increases were seen in certain metal ions including K. Na, Mn and Zn in fungicide treated soils. A compound exhibiting auxin activity was extracted and characterised as 3-Indole-pyruvic acid. However the exact origin of this compound is unknown. It seems likely that it was an extraction artefact since IPyA is highly unstable under the extraction conditions which were employed. The potential for soil auxin activity existed however and was increased two-fold by the addition of the fungicide Captan to the soil. Finally the possible effects of these changes on soil fertility are discussed, particularly in relation to the increased growth response phenomenon, associated with the partial sterilization of soil

Bacteria in amber coal and clay in relation to lithopanspermia

A Study was undertaken to determine if amber, coal and clay samples contain bacteria. ill relation to the possibility that rocks ejected from Earth might contain microorganisms capable of colonizing other planets. A technique for isolating bacteria from rocks was developed which excluded the possibility that any of the rock isolates resulted from contamination. Two species of Bacillus were found in the amber sample, and a species of the same genus Was found in coal bacilli were also commonly found in clay. It is Concluded that species of the spore-forming genus Bacillus Could therefore be ejected from Earth in these geological Substrates and possibly be transferred elsewhere

Bactericidal activity of biosynthesized silver nanoparticles against human pathogenic bacteria

Green synthesis is an attractive and eco-friendly approach to generate potent antibacterial silver nanoparticles (Ag-NPs). Such particles have long been used to fight bacteria and represent a promising tool to overcome the emergence of antibiotic-resistant bacteria. In this study, green synthesis of Ag-NPs was attempted using plant extracts of Aloe vera, Portulaca oleracea and Cynodon dactylon. The identity and size of Ag-NPs was characterized by ultraviolet–visible spectrophotometer and scanning electron microscopy. Monodispersed Ag-NPs were produced with a range of different sizes based on the plant extract used. The bactericidal activity of Ag-NPs against a number of human pathogenic bacteria was determined using the disc diffusion method. The results showed that Gram positive bacteria were more susceptible than Gram negative ones to these antibacterial agents. The minimum inhibitory concentration was determined using the 96-well plate method. Finally, the mechanism by which Ag-NPs affect bacteria was investigated by SEM analysis. Bacteria treated with Ag-NPs were seen to undergo shrinkage and to lose their viability. This study provides evidence for a cheap and effective method for synthesizing potent bactericidal Ag-NPs and demonstrates their effectiveness against human pathogenic bacteria

Cause of Cambrian Explosion - Terrestrial or Cosmic?

We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism fossil evidence contained within meteorites as well as the detection in the upper atmosphere of apparent incoming life-bearing particles from space. In our view the totality of the multifactorial data and critical analyses assembled by Fred Hoyle, Chandra Wickramasinghe and their many colleagues since the 1960s leads to a very plausible conclusion - life may have been seeded here on Earth by life-bearing comets as soon as conditions on Earth allowed it to flourish (about or just before 4.1 Billion years ago); and living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth so being one important driver of further terrestrial evolution which has resulted in considerable genetic diversity and which has led to the emergence of mankind

Author Correction: Drivers of seedling establishment success in dryland restoration efforts

1 Pág. Correción errata.In the version of this Article originally published, the surname of author Tina Parkhurst was incorrectly written as Schroeder. This has now been corrected.Peer reviewe

The effects of fungicides on the microbiology and biochemistry of soils

A study was made of the effects of a wide range of modern fungicides on the microbiology and biochemistry of soils. The addition of fungicides to laboratory incubated soils led to marked changes in the soil microbial equilibrium. Initially fungal potential was decreased, but soon recovered to exceed that of the control at the end of 28 days. Bacterial numbers on the other hand increased dramatically following treatment. Similar changes were seen in field soils which had been treated with fungicides. The response of the cellulolytic fungal flora to field treatment with fungicides was also studied. Changes in the pattern of recolonization occurred, with species such as T. koningii, and P. nigricans becoming dominant. Cellulolytic fungi were largely insensitive to the addition of fungicides to their growth medium. Marked changes in the mineralization of nitrogen followed fungicide treatment. In the field all the fungicides used inhibited nitrification to a greater or lesser extent while levels of the ammonium ion were increased. Similar changes were seen in laboratory incubated soils. Here treatment with high concentrations of fungicides led to nitrification-inhibition while an increase in nitrate production often followed treatment with low concentrations. The amounts of ammonium-N in these soils increased dramatically following treatment. Towards the end of the incubation period (28 days) low concentrations of fungicides led to increases in the total free amino-acid-N content in soil, while the converse was true of high concentrations. Addition of fungicides also led to qualitative changes in the free amino acid content of soils. Increases were seen in certain metal ions including K. Na, Mn and Zn in fungicide treated soils. A compound exhibiting auxin activity was extracted and characterised as 3-Indole-pyruvic acid. However the exact origin of this compound is unknown. It seems likely that it was an extraction artefact since IPyA is highly unstable under the extraction conditions which were employed. The potential for soil auxin activity existed however and was increased two-fold by the addition of the fungicide Captan to the soil. Finally the possible effects of these changes on soil fertility are discussed, particularly in relation to the increased growth response phenomenon, associated with the partial sterilization of soil