Differential isolation of Pythium species from soil by means of selective media, temperature, and pH

1975 ◽  
Vol 21 (5) ◽  
pp. 606-612 ◽  
Author(s):  
R. D. Lumsden ◽  
W. A. Ayers ◽  
R. L. Dow
Keyword(s):  
Gallic Acid ◽  
Acid Medium ◽  
Inoculum Potential ◽  
Pythium Species ◽  
Optimum Temperature ◽  
Isolation Method ◽  
Frequency Method ◽  
Plate Method ◽  
Selective Media ◽  
Mixed Populations

Pythium aphanidermatum, with an optimum temperature for growth at 35C, grew well and was readily isolated from soil on pimaricin–vancomycin medium (MPVM) when incubated for24 h at 38–40C. The pH of the medium affected recovery; maximum numbers developed above pH 6.0. Other Pythium spp. were recovered on MPVM at 20–25C, but were excluded by incubation at 38–40C. These Pythium spp. included P. ultimum, P. paroecandrum, P. irregulare, P. mamillatum, and an unidentified Pythium sp. These species grew well and were readily isolated from soil on gallic acid medium (GAM) when incubated for 24–48 h at 20C. P. aphanidermatum and P. myriotylum grew from mycelium on GAM, but their oospores did not germinate nor could they be isolated from soil on this medium. P. myriotylum grew well on MPVM, but was only rarely isolated, even from soils with known high potential for disease caused by P. myriotylum. Propagules of Pythium were enumerated by a plate-dilution frequency method or by a smear-plate method in serial dilutions of soil in 0.3% water agar. This differential isolation method is valuable for studies on the ecology, survival, and inoculum potential in soils with mixed populations of P. aphanidermatum and other Pythium spp.

scholarly journals Influence of Isolation Method on Recovery of Pythium Species from Forest Nursery Soils in Oregon and Washington

Plant Disease ◽  
2011 ◽  
Vol 95 (5) ◽  
pp. 547-553 ◽  
Author(s):  
Jerry E. Weiland
Keyword(s):  
Pacific Northwest ◽  
The United States ◽  
Pythium Species ◽  
Forest Nursery ◽  
Isolation Method ◽  
Species Identity ◽  
The Pacific ◽  
Forest Nurseries ◽  
Species Richness And Abundance ◽  
Isolated Species

Pythium species are common damping-off pathogens that can cause stunting, chlorosis, and death of conifer seedlings in the Pacific Northwest (PNW) region of the United States. Despite the prevalence and importance of these pathogens in forest nurseries, relatively little is known about the identity of Pythium species associated with forest nursery soils in Washington and Oregon. A limited number of studies have reported P. aphanidermatum, P. irregulare, P. mamillatum, and P. ultimum as the predominant species in the PNW, but most studies of this genus in forest nurseries have not reported Pythium species identity. In an attempt to identify Pythium species associated with forest nursery soils, field surveys were conducted at three forest nurseries (two in Oregon and one in Washington) in 2008 using three isolation methods. Pythium species were isolated by plating soil onto a semiselective medium or by baiting soil with rhododendron leaf disks and Douglas-fir needle segments. One hundred isolates were randomly selected from each isolation method at each nursery (900 isolates total) and identified on the basis of the internal transcribed spacer (ITS) sequence. Nineteen Pythium species were identified during the survey. Species richness and abundance were strongly influenced by both nursery and isolation method. Of the 300 isolates obtained from each nursery, P. irregulare was the most commonly isolated species from nursery A in Washington (65% incidence). P. ‘vipa’ and P. dissotocum were the most commonly isolated species from nurseries B and C in Oregon, respectively (53 and 47% incidence, respectively).

scholarly journals Mefenoxam Sensitivity, Aggressiveness, and Identification of Pythium Species Causing Root Rot on Floriculture Crops in North Carolina

Plant Disease ◽  
2015 ◽  
Vol 99 (11) ◽  
pp. 1550-1558 ◽  
Author(s):  
E. C. Lookabaugh ◽  
K. L. Ivors ◽  
B. B. Shew
Keyword(s):  
North Carolina ◽  
Host Species ◽  
Root Rot ◽  
Internal Transcribed Spacer ◽  
Ornamental Plants ◽  
Pythium Species ◽  
Selective Media ◽  
Microtiter Plates ◽  
Pythium Root Rot

Herbaceous ornamental plants exhibiting symptoms of Pythium root rot were collected from 26 greenhouses in 21 counties in North Carolina (NC) from 2010 to 2012. Plant symptoms ranged from mild stunting to severe wilting, root rot, and death. Roots were plated on selective media, and 356 isolates of Pythium were recovered from 34 host species. Selected isolates were identified by sequencing of the internal transcribed spacer (ITS) rDNA gene region. Seventeen Pythium species were identified, with P. aphanidermatum, P. irregulare, and P. myriotylum comprising 75% of the 320 isolates sequenced. Twelve of the 26 greenhouses had more than one species present. Mefenoxam sensitivity was tested in vitro by growing isolates in wells of microtiter plates containing clarified V8 agar amended with 100 µg a.i./ml mefenoxam. Colonization was scored after 24 to 48 h using a scale of 0 (no growth) to 5 (entire well colonized). Fifty-two percent of the isolates were resistant to mefenoxam (mean score ≥4). All 32 isolates of P. myriotylum were sensitive, whereas sensitivity varied among isolates of P. aphanidermatum and P. irregulare. Resistant and sensitive isolates of the same species were found within the same greenhouses. The aggressiveness of P. aphanidermatum and P. irregulare isolates was evaluated on poinsettia, Gerbera daisy, and petunia. P. aphanidermatum was more aggressive than P. irregulare on poinsettia and petunia; symptoms were mild and no differences in aggressiveness were observed on Gerbera daisy. Sensitivity to mefenoxam was not related to aggressiveness.

scholarly journals Studies in the mechanism of enzyme action. I.—Rôle of the reaction of the medium in fixing the optimum temperature of a ferment

1921 ◽  
Vol 92 (642) ◽  
pp. 1-6 ◽  
Keyword(s):  
Enzyme Activity ◽  
Temperature Effect ◽  
Acid Medium ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Optimum Temperature ◽  
Hydrogen Ion Concentration ◽  
Enzyme Action

Previously, it has been shown for the enzyme maltase —enzyme requiring an acid medium in which to act to best advantage—that increase in the acidity or hydrogen ion concentration of the medium in which the enzyme acts, beyond the optimum acidity, leads to a fall of optimum temperature. The mechanism of his temperature of this temperature effect appears clearly to be due to a certain disablement of the enzyme activity, estimated at the optimum temperature point; which decrease of activity is itself a function of the degree of acidity of the medium in excess of that necessary to produce optimum activation. Being in this way a disablement effect, the question arises whether, by adding to the quantity of enzyme in action, the lowering of optimum temperature which takes place can be controlled. To answer that question, the experiments described in the present paper were undertaken. For the investigation, the enzyme used is the maltase of Aspergillus oryzœ , the same preparation being employed as studied by us in two previous communications, a specially active specimen of takadiastase, purified by repeated solution in water and reprecipitation by alcohol.

scholarly journals AN IMPROVED METHOD FOR ISOLATION OF THIELAVIOPSIS PARADOXA FROM STEM BLEEDING AFFECTED COCONUT PALMS

CORD ◽  
1991 ◽  
Vol 7 (01) ◽  
pp. 34 ◽  
Author(s):  
Anil Kumar ◽  
K.K.N. Nambiar
Keyword(s):  
Plant Pathogens ◽  
Improved Method ◽  
Isolation Method ◽  
Selective Media ◽  
Important Disease ◽  
Basic Necessity

Stem bleeding of coconut caused by Thielaviopsis paradoxa (de Seynes) Von Hohnel is an important disease affecting coconut in many countries (Menon and Pandalai, 1958; Ohler, 1966, Nambiar and Sastry, 1988). lsolation of the pathogen from diseased tissues on different agar based media has given inconsistent results (Anon., 1976; Anon., 1986), None of the selective media reported for certain related fungi viz., T. basicola (Berk and Br.) Ferr. (David, 1978;Tsao and Bricker, 1966) and Ceratocystis wagnerii Goheen and Cobb (Hicks et al., 1980) proved useful for the isolation of T. paradoxa Since, standardization of an isolation method is a basic necessity for any study on plant pathogens, an attempt was made to improve upon existing methods.

scholarly journals ISOLASI DAN IDENTIFIKASI BAKTERI ASAM LAKTAT DARI MAKANAN TRADISIONAL SUKU REJANG DI PROVINSI BENGKULU: “LEMEA”

Alotrop ◽  
2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Moga Kurnia ◽  
Hermansyah Amir ◽  
Dewi Handayani
Keyword(s):  
Lactic Acid ◽  
Teacher Training ◽  
Lactic Acid Bacteria ◽  
Plate Method ◽  
Titration Method ◽  
Training And Education ◽  
Selective Media ◽  
Gram Staining ◽  
Home Industries ◽  
De Man

This study aims to specify the genus of lactic acid bacteria (LAB) in "lemea" and measure the activity of LAB isolates in producing lactic acid. The sample "lemea" came from one of the home industries in Daspetah Village, Ujan Mas District, Kepahiang Regency which was fermented for 7 days. The research was conducted from February to May 2019, at the Learning Laboratory of Biology and Chemistry, Faculty of Teacher Training and Education, University of Bengkulu. Isolation of LAB from "lemea" using selective media De Man, Rogosa and Sharpe (MRS) supplemented with 0.5% CaCO3 using the pour plate method. The steps of this study include, sampling "lemea", isolation of LAB, identification of macroscopic and microscopic bacteria (Gram staining) and determining% of lactic acid levels using the titration method to measure the activity of LAB isolates. The results identification of BAL isolates in "lemea" obtained two LAB isolates with codes of LK1 and LK2 isolates that had cocci, Gram positive and did not have spores. The measurements results of LAB activity in producing lactic acid, for LK1 isolates, obtained lactic acid levels of 1.92% while LK2 isolates were 1.56% of the local mass. According to the results identification,LK1 and LK2 isolates are the genus Leuconostoc and the highest activity in producing lactic acid in LK isolates.

Distribution of Phytophthora and Pythium species in soils in the Continental United States

1970 ◽  
Vol 48 (2) ◽  
pp. 377-384 ◽  
Author(s):  
Floyd F. Hendrix, Jr. ◽  
W. A. Campbell
Keyword(s):  
United States ◽  
Phytophthora Cinnamomi ◽  
The United States ◽  
Soil Samples ◽  
Pythium Species ◽  
Selective Media ◽  
Trapping Method ◽  
Heterothallic Species

The Pythium flora of 2132 soil samples from all sections of the United States was determined using an apple trapping method and two selective media. Isolates of the P. irregulare – P. debaryanum complex were obtained from 90% of the samples, and made up 55% of the 10 566 isolates examined. Isolates referable to the P. dissotocum – P. perniciosum complex, P. spinosum, P. splendens, P. ultimum, P. vexans, and heterothallic forms including P. sylvaticum, P. heterothallicum, and P. intermedium were obtained from 5 to 15% of the samples. Pythium afertile, P. aphanidermatum, P. dissotocum – P. perniciosum, P. irregulare – P. debaryanum, P. spinosum, P. torulosum, P. ultimum, and the heterothallic species were found in soil samples from 60% or more of the sections of the country sampled. The following species were isolated infrequently: P. acanthicum – P. oligandrum complex, P. catenulatum, P. helicoides – P. oedochilum complex, P. mamillatum, P. middletoni, P. myriotylum, P. paroecandrum, P. periplocum, P. prolatum, P. pulchrum, P. rostratum, P. vexans, Phytophthora cinnamomi, and P. parasitica.

scholarly journals ISOLASI DAN UJI KOMPATIBILITAS BAKTERI HIDROLITIK DARI TANAH TEMPAT PEMROSESAN AKHIR TALANGAGUNG, KABUPATEN MALANG

2020 ◽  
Vol 19 (2) ◽  
Author(s):  
Prilya Dewi Fitriasari ◽  
Nanda Amalia ◽  
Susiyanti Farkhiyah
Keyword(s):  
Proteolytic Activity ◽  
Organic Waste ◽  
Skim Milk ◽  
Enzymatic Activities ◽  
Bacterial Isolates ◽  
Cellulolytic Bacteria ◽  
Bacterial Isolation ◽  
Plate Method ◽  
Selective Media ◽  
Bacterial Selection

Talangagung landfill, Malang Regency has used the controlled landfill method. The landfill process produces methane gas that has been flowed as fuel so that it is estimated that there are bacteria with a variety of enzymatic activities that have worked in degrading waste. The purpose of this study was to isolate bacteria from landfill and determine the ability to produce amylase, protease, lipase, and cellulase and test the compatibility of bacteria. The methods used include bacterial isolation using the pour plate method and purification of bacterial isolates using the streak plate method. Bacterial selection is done on selective media containing starch, tributyrin, cellulose, and skim milk. There were 21 bacterial isolates successfully isolated 13 consisting of bacterial isolates showed proteolytic activity, 10 cellulolytic bacteria, 8 amylolytic, and 15 lipolytic. The isolates that show compatible results are BTA 5.7.14, BTA 5.7.7, BTA 5.7.12, and BTA 5.7.6 therefore they can be used as a potential consortium for organic waste recycle.   

scholarly journals Enumeration of Microflora from Ingredients and Idli Batter

2021 ◽  
Author(s):  
Viswanatha Angadi ◽  
B. Ramachandra ◽  
D.B. Puranik ◽  
R. Prabha
Keyword(s):  
Potato Dextrose Agar ◽  
Local Market ◽  
Fermented Foods ◽  
Black Gram ◽  
Plate Method ◽  
Selective Media ◽  
Idli Batter ◽  
Science College ◽  
Natural Microflora ◽  
Dairy Science

Background: Microorganisms are responsible for characteristic changes in the fermented foods. They result in the sequential changes during fermentation of food, resulting in souring, leavening and changes in flavour, body and texture. The present study was aimed to enumerate the natural microflora present in raw ingredients used as well in fresh and fermented idli batter. Methods: Study was conducted during the period 2019-2020 to develop solid state fermented cultures for whey based idli batter at Department of Dairy Microbiology, Dairy Science College, Bangalore. The raw ingredients used for idli preparation were sourced from local market of Bangalore. Lactic counts such as leuconostoc, enterococci, pediococci and lactobacilli, as well as yeast counts were enumerated using different selective media by pour plate method. Result: The leuconostoc count of rice rava, black gram dhal and fresh idli batter on sucrose agar ranged from 2.0 to 3.78 log10 cfu/g; Lactobacilli count on MRS agar varied from 2.0 to 4.11 log10 cfu/g. Yeast count on potato dextrose agar ranged from 1.6 to 2.3 log10 cfu/g. Lactic counts (includes leuconostoc, lactobacillus, pediococci, enterococci) in fresh idli batter ranged from 3.63 log10 cfu/g to 4.77 log10 cfu/g, whereas in fermented idli batter varied from 2.56 log10 cfu/g to 8.74 log10 cfu/g. The yeast counts in fermented batter ranged from 9.23 to 9.56 log10 cfu/g.

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