Biological studies of some tussock-grassland soils

Abstract

SummaryA quantitativ~ and qualitative study of the bacteria of three tussock-grassland soils ·has been made to determine the relative influence of vegetation and soil tyPe on ~he flora.Greatest numbers of bacteria tend to occur in the topsoil rather than in the subsoil and in the spring rather than the summer or autumn.Of the five mam taxonomic groups recognised, one (the Achromobacteriaceae) is considered to be chiefly derived from the leaf flora while the distribution of the aerogenic fermenters (Enterobacteriaceae and Aeromonas) is considered to be related to the relative organic content and the extent of the rooting systems in the three soils. The predominant flora consists chiefly of pseudomonads and is very similar in all three soils.Generally, the flora consists of strongly oxidative and proteolytic strains, psychrophilic or mesophilic rather than thermophilic, requiring readily available 80urces of energy but not requiring growth factors and capable of using ammonium as a sole source of nitrogen. There is a positive correlation between the saccharolytic and proteolytic activities of the strains and denitrification.Generally, it is considered that the activity of the flora is controlled primarily by the condition of the plant cover and particularly by root activity. Neither moisture nor temperature appear to be serious limiting factors. INTRODUCTIONThe present study of three areas of tussock grassland (previously described, Thornton 1958) was intended, firstly, to describe the nature of the microfauna and microflora of the soils and, secondly, to determine the relative influence of vegetation and soil type on the fauna and flora.

Numerical Taxonomy of Phylloplane Bacteria Isolated from Lolium perenne

“…Pigmentation may confer resistance to ultraviolet radiation in sunlight (Mathews & Sistrom, 1960) or desiccation (Grinstead & Lacey, 1973). By contrast the soil flora generally includes large populations of Gram-positive, non-chromogenic bacteria classified as Arthrobacter, Bacillus and Streptomyces (Stout, 1960;Goodfellow, 1969;Jensen, 1971 ;Holm & Jensen, 1972;Lowe & Gray, 1972) though Gram-negative bacteria are common in some grassland soils (Stout, 1961) and in the rhizosphere (Rovira & Brisbane, 1967 Little is known of the significance of this bacterial flora to the plant or to other indigenous leaf surface micro-organisms. However, the numerical classification of the bacterial flora of Lolium perenne leaves has made it possible to select strains objectively for interaction studies.…”

“…or as pink chromogens (clusters I and 7). Although it is difficult to compare numerical phenetic classifications with those based on only a few subjectively chosen characters, it should be noted that Stout (1960) recorded large numbers of Pseudomonas spp., Xanthomonas spp. and pink chromogens (flavobacteria) from Lolium leaves.…”

First record of protozoan parasites, Tetrahymena rostrata and Callimastix equi from the edible oyster in Sundarbans region of West Bengal, India

“…It may also infect accidentally injured worms. From the point of view of food, it depends on the turnover of microbial life and the frequent incidence of dead worms, rotifers, nematodes, tardigrades or even dead ciliates, as much as the incidence of living enchytraeids which in nature are probably only occasionally parasitized (Stout 1958). The ciliates are attracted by histolysis and by peptone.…”

Long-term effects of paraquat-diquat and additional weed control treatments on some physical,biological,and respiratory properties of a soil previously under grass

“…Duplicate plates were inoculated using two media, glucose-tryptone-yeast (GTY) extract agar (Stout 1958) and the fluorescent pseudomonad medium of Sands & Rovira (1970). Glucose-tryptone broths (Stout 1958) were also inoculated from each dilution.…”

“…Duplicate plates were inoculated using two media, glucose-tryptone-yeast (GTY) extract agar (Stout 1958) and the fluorescent pseudomonad medium of Sands & Rovira (1970). Glucose-tryptone broths (Stout 1958) were also inoculated from each dilution. Two series of plates were prepared with the glucose-tryptone-yeast extract agar; one was inoculated directly and the second, to estimate the spore count, was inoculated after pasteurisation of the dilutions for 10 min at 80°c.…”