Counts Of Actinomycetes Research Articles

Decomposition of wheat and barley straw treated with urea-sulfuric acid

Wheat straw treated with 0.5 or 1.0 ml/g urea-sulfuric acid (1:1 acid in water v/v) and incubated in Protneuf or Woodburn silt loam soils in the laboratory decomposed faster than nontreated straw the first 4–6 weeks but at 12 weeks the nontreated straw had decomposed 25%–45% more. In a field experiment, urea-sulfuric acid treated straw, removed at 40-day intervals over 160 days, decomposed faster than nontreated straw. The differences were attributed to salt buildup in the laboratory samples, where electrical conductivities up to 17.6 dS/m were observed. In the field, leaching removed the excess salts. Nitrification produced up to 1875 mg NO 3 − N/kg Portneuf silt loam soil in the laboratory, indicating that nitrifying bacteria were not suppressed by the salt. Total plate counts with no straw were 1.8 × 106 microorganisms/g and with urea-sulfuric acid treated straw were 15.7 × 106/g soil after 14 days incubation. The respective actinomycete counts were 0.3 × 106 and 6.7 × 106/g for the no straw and straw-treated soils, respectively. The urea-sulfuric acid treatments suppressed straw decomposition in the laboratory and accelerated straw decomposition in the field.

Distribution of microorganisms, total biomass, and enzyme activities in different particles of brown soil

A soil sample from the Ap horizon of an arable brown soil was fractionated by wet sieving, and seven size fractions of organic and mineral soil particles were separated. The organic fractions formed only 2.2% of the soil dry mass, but contained 41.5 and 29.12% of the total soil content of carbon and nitrogen, respectively, and thus represented an important reservoir of readily utilizable nutrients. Organic particles also accumulated most of the soil enzyme activities, determined asβ-glucosidase,β-acetylglucosaminidase, and proteinase activity. The highest counts of bacteria, actinomycetes, and fungi per gram of the soil fractions were obtained with the organic particles, but for the most part microorganisms accumulated in the silt-clay fraction. All soil fractions except the coarsest organic particles contained higher counts of oligotrophic bacteria than copiotrophic ones. Microbial counts, ATP contents, and enzyme activities decreased significantly with decrease in size of the organic soil particles, and increased with decrease in size of the mineral soil particles. Thus, the coarse organic particles >5 mm and the silt-clay fraction <0.05 mm represent the sites with the highest concentrations of microorganisms, ATP contents, and enzyme activities in the arable brown soil under test.

Ecology of the Streptomycetes Flora in the Desert Soil of Kuwait

Summary The distribution of the streptomycetes flora in four plant communities in the desert of Kuwait was investigated. The results show that the counts of actinomycetes vary considerably with the community. Maximal counts of 1156 × 10 4 /g soil were found in the rhizosphere of Rhanterium epapposum . The saline habitat, represented by Salicornia herbaceae and Nitraria retosa communities, was very poor in total viable bacteria and actinomycetes. From Rhanterium, Cyperus , and Salicornia communities, 256 actinomyctes isolates were obtained; they were identified as Streptomyces (254), Streptoverticillium (one isolate) and Nocardia (one isolate). The Streptomyces isolates belonged to seven color series. The dominant one was the Grey series (72%), while the Green series was rarely recorded. The Red series was more frequent (14%) than the Yellow, Blue and Violet series. Species identification of the 254 Streptomyces isolates indicated the presence of 65 Streptomyces species in the desert of Kuwait. S. olivaceus was comparatively frequent (12.2%), followed by S. albogriseolus (8.7%), S. resistomycificus (5.5%), S. lydicus (4.7%), S. echinatus and S. plicatus (each 4.3%) and S. fumanus (3.9%). Other species represented 0.4–3.1%. Each community was characterized by the presence of particular species that were found in no other community. In the roots of the different plants investigated particular Streptomyces species were found. This was also observed with different non-rhizosphere soils of different communities. Some unidentifiable Streptomyces species were characterized by wedged spore surfaces distinct from smooth and warty surfaces, while other species showed peculiar morphological characteristics when growing on glycerol asparagine agar.

QUANTIFICATION OF MOULD CONTAMINATION IN SULPHURED AND UNSULPHURED MALT

The use of different techniques for assesment of mould contamination in barley and malt is illustrated by reference to an examination of the effect of sulphuring of malt. Reductions in levels of mould contamination were detected in sulphured malts, compared with corresponding unsulphured controls, using direct and dilution plating techniques. Viable counts of wild yeasts, bacteria and thermophilic actinomycetes were also lower in sulphured malts.

Distribution of Enteric Viruses and Microorganisms in Long-Term Sewage-Treated Soil

To determine whether long-term sewage treatment can take place without a pollution risk for soil and groundwater, samples from sewage irrigation fields in West Berlin which have been in use since about 1890 were analyzed for enteric viruses and microorganisms. Enteric viruses were detected in only seven samples from a total number of eighty seven taken from different soil depths. With only one exception, no viruses were found below 60 cm. No viruses were detected in groundwater samples. Long-term sewage irrigation did not result in significant changes in the colony courts of aerobic soil bacteria, but the counts of anaerobic bacteria and actinomycetes were slightly elevated and those of microscopic fungi slightly decreased. Potentially pathogenic bacteria were not detected in soil below 90 cm.

Influence of foliar application of pesticides on leaf extracts and phylloplane microflora of corn.

The effect of foliar application of captan, dithane, carbaryl and atrataf on the quantity of total carbohydrates, total amino acids and total nitrogen leached from corn leaves and on the phylloplane counts of fungi, bacteria and actinomycetes was studied. Leaf extracts were analyzed for amino acids, carbohydrates and nitrogen and were correlated with microbial counts. Generally the microbial counts were less than the control in treated samples and a significant change in Gram-negative bacteria in all treatments was recorded. All treated leaf extracts showed less total amino acids and total nitrogen though they were rich in carbohydrates as compared with the control.

Rhizosphere micro-organisms in relation to the apple replant problem

One of the factors giving rise to soil sickness in apple orchards is the rhizosphere microflora. The composition of the microbial coenosis in the rhizosphere changes with increasing age of the apple trees. An increase in the counts of micromycetes and actinomycetes and a decrease in bacterial counts was found in agreement with the decreasing pH of the rhizosphere soil. The presence of fluorescent pseudomonads in the rhizosphere of old apple trees was rare, but the planting of apple seedling into sick soil induced their proliferation. The relative proportion of individual genera of micromycetes changed according to the tree age; fungi of the genus Mucor were more often found in the rhizosphere of younger trees than in that of older ones while fungi of the genus Penicillium had an opposite trend. Biological tests showed that Penicillium fungi form the majority of the phytotoxic microflora. The amount of phytotoxic micromycetes was higher in ‘sick’ soil as compared with control soil in which apple trees had not been grown for at least 15 years. Higher numbers of phytotoxic micromycetes were isolated also from the rhizosphere of apple seedlings grown in ‘sick’ soil as compared with those growing in control soil. An increase in the amount of phytotoxic micromycetes in apple tree rhizosphere could be induced by mere addition of 5% (w/w) ‘sick’ soil to the soil in which apple trees were grown for the first time. By adding sterilized ‘sick’ soil, the amount of phytotoxic micromycetes in the apple seedling rhizosphere was not affected. Increased numbers of phytotoxic micromycetes affected negatively the growth of apple trees and the morphology of apple tree roots. This demonstrated the possibility of transfer of a factor participating in the etiology of soil sickness in apple orchards.

Studies on humic acids decomposing streptomycetes: I. Types prevailing in Egyptian soils

The study comprises the enumeration and identification of humic acids decomposing actinomycetes in soils of Egypt. Counts of total actinomycetes (0.5 – 4.0 × 10 6 /g) were not correlated with either soil texture of the organic matter content and the C/N ratio of the soil. Humic acids decomposers represented 2.0 – 25.5% of total actinomycetes counts. Lower densities (17 to 25 × 10 3 /g) were encountered in sand, but clay soils harboured somewhat higher population (18–27 × 10 4 /g). A total of 201 representative isolates of humic acids decomposers were obtained from different soils. All of these isolates were found to belong to the genus Streptomyces , and most of them are characterized by grey mycelium. Twenty-eight different species of true humic acids decomposing Streptomyces were recognized. Huminsäure-zersetzende Aktinomyzeten ägyptischer Böden wurden zahlenmäßig erfaßt und identifiziert. Die Gesamtzahl der Aktinomyzeten (0,5 – 4,0 × 10 6 /g) stand weder mit der Bodentextur noch mit dem Gehalt an organischer Substanz und dem C: N-Verhältnis des Bodens in Beziehung. 2,0 – 25,5% der Aktinomyzeten waren Huminsäurezersetzer. Niedrigere Dichten wurden in Sand ermittelt (17–25 × 10 3 /g), höhere in Lehmböden (18–27 × 10 4 /g). Insgesamt wurden 201 repräsentative Isolate von Huminsäurezersetzern aus den verschiedenen Böden gewonnen. Sie gehören sämtlich der Gattung Streptomyces an. Für die meisten ist graues Myzel charakteristisch. Es wurden 28 verschiedene Spezies an echten Huminsäure-zersetzenden Streptomyzeten festgestellt.

Effect of foliar application of antibiotics and gibberellic acid on the rhizosphre microflora of pea, infected with Verticillium dahliae.

A study was made of the effects of foliar spray of bacitracin, chloramphenicol and gibberellic acid on the rhizosphere microflora of pea seedlings (Pisum sativum L.) infected with Verticillium dahliae. The antibiotics increased fungus and actinomycete counts and reduced the bacterial populations in the rhizosphere. Gibberellic acid at 10 ppm concentration reduced all three groups of microorganisms while at 100 ppm fungi and actinomycetes increased slightly. Invariably the rhizosphere effect was as follows: bacteria leads to fungi leads to actinomycetes. Foliar sprays also affected percentage occurrence of particular genera of fungi in the rhizosphere; for example, Trichoderma spp. were stimulated by all the treatments, the maximum being with 10 ppm gibberellic acid, even though the total fungus count was reduced. The disease severity was markedly reduced by foliar sprays.

Effect of some pesticides on certain micro-organisms, contributing to soil fertility

A pot experiment was run for studying the effect of Temik (insecticide and nematocide), Orthocide (fungicide), and Treflan (herbicide) on certain desirable soil micro-organisms. Total counts of bacteria, actinomycetes or fungi were mostly lower in the treated than in the untreated soil. Aerobic cellulose-decomposers were either stimulated or depressed. Despite the temporarily slight stimulation, observed in some instances at the initial periods, the effect of the pesticides on counts of Azotobacter, N-fixing clostridia, and ammonifiers was afterwards depressed. The period of retardation or stimulation differed according to type of pesticide and type of micro-organisms under study. However, the autotrophic nitrifying bacteria, especially ammonium-oxidizers, seemed to be more sensitive and their counts in treated soil were sharply depressed.

The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. I. Rhizosphere Bacteria, Actinomycetes and Fungi

An investigation was made of the microflora associated with unsuberized roots of Eucalyptus marginata and Eucalyptus calophylla raised in different soils. The studies were made for 'conducive' lateritic soil (in which E. marginata is susceptible to infection by Phytophthora cinnamomi but E. Calophylla is resistant); and in 'suppressive' loam soil in which both eucalypt species are unaffected by the pathogen. Lateritic soil in some cases contained natural infection of P. cinnamomi. Rhizospheres of both species contained larger microflora populations (expressed as numbers per g of root) than in the soils. In general, the population of rhizosphere microflora was greater for E. Marginata than E. calophylla seedlings in the uninfected lateritic soil. Qualitative differences were also recorded in populations of bacteria, actinomycetes and fungi, and in particular, fluorescent pseudomonads were more numerous in the rhizosphere of E. marginata seedlings. Eucalypt seedlings raised in loam soil harboured greater microbial populations than in lateritic soil. This could in part be attributed to the higher nutrient and organic matter status of the loam. E. marginata had a greater total rhizosphere population, but actinomycetes were more numerous in the rhizosphere of E. calophylla. Qualitative differences in populations of bacteria, actinomycetes and fungi were also noted. In naturally infected lateritic soil the microflora populations were invariably lower than for the other soils. When the counts of bacteria and actinomycetes were expressed as numbers per mm2 of root surface, E. calophylla had a significantly higher number of propagules per unit area than E. marginata. The loam soil was an exception; there E. marginata had three times as many bacteria per unit area of the root surface as E. calophylla. It is suggested that the microflora population differences recorded for the two eucalypts in lateritic soil may contribute to the differential susceptibility of species to infection by P. cinnamomi; and that the higher populations of microflora in the loam soil contribute to the suppression of P. Cinnamomi in that soil.

Microbial changes in clover rhizosphere after foliar and soil application of cobalt.

Application of cobalt(II) nitrate to the leaves of red clover (Trifolium pratense L.) resulted in a pronounced increase of dry weight and the number of root nodules. Counts of bacteria in the rhizosphere, content of ammonia and production of carbon dioxide in rhizosphere soil were also higher, whereas the content of nitrates decreased. Differences in the counts of bacteria, actinomycetes, Azotobacter, anaerobic bacteria and cellulose decomposing bacteria in the rhizosphere of control and treated plants were not directly related to the way of application of cobalt. Genera Penicillium, Fusarium and Trichoderma predominated among fungi. The relative occurrence of penicillia was higher after the application of cobalt, the incidence of fusaria was lower. The effects of foliar and soil application of cobalt on rhizosphere microflora were not identical.

Airborne Actinomycetes in the Atmosphere of Kuwait

Summary The distribution of actinomycetes in the atmosphere of Kuwait was studied during 6 months, from January to June, 1973. Total viable counts of actinomycetes were higher in the atmosphere of the crowded commercial locality (Mubarakiya) than in the quieter residential one (Suliabikhat). Maximum counts were obtained during February in the two localities. Lower counts during the hot dry season (May and June) may be attributed to high temperature and low relative humidity in this season. The genus Streptomyces was dominant in the atmosphere and in the soil of the two studied localities. The genus Nocardia was found to be of higher incidence in the soil than in the atmosphere. Micropolyspora sp. were more frequent in the atmosphere and in the soil of the crowded locality than in the quieter residential one. Classification of the genus Streptomyces to sections and series was tried. The Rectus (R) and the Spira (S) sections were dominant in the atmosphere of the two localities, while in their soil the Spira (S) section was highly dominant. The gray series was found to be the dominant one in all the sections recorded. The blue series among the (S) section was recorded only in the soil of the two localities.

Methods for Examining the Microflora of Mouldy Hay

A comparison of four methods of estimating the microflora of mouldy hay showed that more micro‐organisms were removed by washing samples than by blowing in a small wind tunnel. By contrast, actinomycete spores were estimated more efficiently from air using an Anderson Sampler than by plating diluted washings because fewer bacteria were blown than washed off the hay. Estimates of fungal spores were larger from counts in haemocytometer cells than by dilution plating but counts of actinomycetes and bacteria were higher by dilution plating. Fungi grew equally well from air or water suspensions and with the Cascade Impactor and Anderson Sampler their numbers were estimated with less variation than for the numbers of ‘actinomycetes and bacteria’even on improved media and after correcting for viability, clumping and interference between colonies.

Preservation of High-Moisture Corn: A Microbiological Evaluation

Ammonia, ammonium isobutyrate, isobutyric acid, and propionic-acetic acid at concentrations of .5%, 1.75%, 1.5%, and 1.2%, respectively, were applied to comparable 52.8m3 lots of freshly harvested yellow dent corn having a moisture content of 27%. Treated corn was stored in partially open wooden bins. Harvestore® and barrell storage of untreated corn were included as controls. Temperature and microbiological changes were evaluated throughout 6 mo of storage. As the corn came from the field, log counts of 6.3, 5.8, 5.3, and 3.0 per g were determined for bacteria, molds, yeasts, and actinomycetes, respectively. All chemicals immediately reduced bacterial and actinomycete counts and eliminated molds and yeasts. All treatments after approximately 30 days’ storage had secondary fungal growth. Scopulariopsis brevicaulis predominated on ammonia-treated corn; Mucorales, and species of Monascus, Peniaillium, Fusarium, and Aspergillus flavus, as well as A. fumigatus, were in ammonium isobutyrate-treated corn. A. flavus was the predominant mold infecting isobutyric acid and propionic-acetic acid treated corn late in storage.

Studies in Actinomycetes in Egyptian Soils I. The Distribution of Actinomycetes

The distribution of actinomycetes in Egyptian soils was investigated, using four media. There was no significant difference between the counts obtained on different media in each particular soil. The effect of the soil ecological and geographical situation tends to influence the distribution of actinomycetes more significantly than the soil texture, as evidenced in most cases by significantly higher numbers of actinomycetes in Upper than in Lower Egypt soils. The soil organic matter, clay, and nitrogen content seemed to have positive correlation with the counts of actinomycetes, while CaCO3 and total soluble salts indicated a negative correlation. Die Verteilung der Aktinomyzeten in ägyptischen Böden wurde auf vier Nährmedien ermittelt. Die zahlenmäßigen Unterschiede auf unterschiedlichen Medien waren statistisch nicht gesichert. Die Zahl der Aktinomyzeten wird mehr durch die okologischen und geographischen Faktoren als durch die Bodentextur beeinflußt. In den oberagyptischen Böden sind im allgemeinen mehr Aktinomyzeten als in den unterägyptischen. Korrelationen zwischen Aktinomyzetenzahl und Gehalt an organischerSubstanz, Tonmineralien und Stickstoff sind positiv, CaC03-und Gesamtsalzgehalt hingegen negativ.

An investigation into the possible changes in the microbial population of soils stored at ?15�C

The effect of storing soils at −15°C on their microbial populations has been investigated. The counts of actinomycetes, bacteria, and fungi in soils stored frozen for various periods of time and thawed differ from those obtained from unfrozen soils. The differences are sometimes negligible, but extreme changes do occur. Counts of actinomycetes, and to some extent (though less consistently) those of bacteria, tend to fall with time of storage, while fungal counts increase in at least two out of four experiments. The most extreme differences are not associated with any specific period of storage.

Selective isolation of aerobic Actinomycetes.

The composition of an arginine-glycerol-salt medium (AGS), suitable for the selective isolation of aerobic actinomycetes, was given. When soil samples were treated with calcium carbonate and plated on the AGS medium, higher total and relative plate counts of actinomycetes were obtained than when other media and methods were used.

Selective Isolation of Aerobic Actinomycetes

The composition of an arginine-glycerol-salt medium (AGS), suitable for the selective isolation of aerobic actinomycetes, was given. When soil samples were treated with calcium carbonate and plated on the AGS medium, higher total and relative plate counts of actinomycetes were obtained than when other media and methods were used.

Studies on the occurrence and activity of fungi in a wheat-field soil

The occurrence and activity of fungi in a wheat-field soil has been investigated by plating techniques and by direct isolation. Over 210 fungi have been isolated. A high proportion of the fungi obtained by hyphal isolation are species which were rare or absent from dilution plates. In contrast to dilution methods, where the most abundant fungi isolated were species of Penicillium, Rhizopus, Mucor, Cladosporium and Fusarium, many fungi obtained from hyphae remain sterile in culture. Rhizoctonia solani, Ophiobolus graminis, Rhizoctonia spp. and several Basidiomycetes were obtained by hyphal isolation. Little difference in fungal count has been found between samples collected at 1 and 3 in., but significantly fewer fungal units were obtained from a subsurface horizon at 6 in. deep. Throughout the year fungi showed a well-marked periodicity, with highest numbers of viable units in the soil during the wet winter period. Both viable spores and viable hyphae were present in low numbers during the dry summer period; some fungi, however, survived the summer as hyphae. Bacterial and Actinomycete counts also showed a similar seasonal periodicity. Cultivation and incorporation of wheat residues with the soil greatly increased fungal numbers and activity, particularly in the neighbourhood of the residues. Bacterial numbers likewise increased greatly after cultivation, but Actinomycetes showed comparatively little change in number. The occurrence and activity of specific fungi are discussed. The data indicate that many species have very short periods of activity in the soil, but are always present.