Pythium Species and Isolate Diversity Influence Inhibition by the Biological Control Agent Streptomyces lydicus

Disease control of soilborne pathogens by biological control agents (BCAs) is often inconsistent under field conditions. This inconsistency may be partly influenced by pathogen diversity if there is a differential response among pathogen species and isolates to selected BCAs. The responses of 148 Pythium isolates obtained from soil at three forest nurseries and representative of 16 Pythium spp. were evaluated in the presence of Streptomyces lydicus strain WYEC108 in an in vitro assay. Percent growth inhibition, inhibition zone distance, mortality, and growth rate were recorded for each isolate, and data were analyzed for effects of species and isolate. Responses of three Pythium spp. (Pythium irregulare, P. sylvaticum, and P. ultimum) were further analyzed for a location (nursery) effect. Although S. lydicus inhibited all Pythium isolates, differences in percent growth inhibition, inhibition zone distance, and mortality were observed among Pythium spp. and isolates. Small but significant location effects were also noted. Growth rate also varied among Pythium spp. and isolates and was found to strongly bias percent growth inhibition and, to a lesser degree, inhibition zone distance; depending on which measure was used, slower-growing isolates appeared less sensitive (growth inhibition) or more sensitive (inhibition zone) to S. lydicus than faster-growing isolates. Results illustrate the importance of using multiple, representative pathogen isolates in preliminary BCA inhibition assays as well as accounting for the effect of pathogen growth rate on pathogen inhibition by BCAs. Future studies should take pathogen diversity into account when evaluating biological control efficacy.

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A laboratory investigation of Paulinia acuminata (DeGeer) (Orthoptera: Acrididae) as a biological control agent for Salvinia molesta

Bulletin of Entomological Research ◽

10.1017/s0007485300017946 ◽

1979 ◽

Vol 69 (1) ◽

pp. 111-114 ◽

Cited By ~ 5

Author(s):

I. F. Chisholm

Keyword(s):

Biological Control ◽

Growth Rate ◽

Plant Tissue ◽

Feeding Rate ◽

Consumption Rate ◽

Biological Control Agent ◽

Control Agent ◽

Salvinia Molesta ◽

Population Densities ◽

Lake Kariba

AbstractThe feeding rate of nymphs of Paulinia acuminata (Deg.) on Salvinia molesta was studied in the laboratory using single nymphs on different numbers of Salvinia leaves. Each successive instar ate more plant tissue, but at population densities likely to occur in nature it was unlikely that consumption rate could match the natural Salvinia growth rate. The controlling effect of Paulinia on Salvinia in Lake Kariba, Rhodesia, may therefore be negligible.

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Effect of Bactericine as a Treatment for the Control of Listeria monocytogenes in Refrigerated Meat Products

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.781-784.1322 ◽

2013 ◽

Vol 781-784 ◽

pp. 1322-1327

Author(s):

Li Juan Yu ◽

Li Liu ◽

Hong Xing Zhang ◽

Yuan Hong Xie ◽

Hui Liu ◽

...

Keyword(s):

Biological Control ◽

Listeria Monocytogenes ◽

Antimicrobial Agent ◽

Growth Inhibition ◽

Biological Control Agent ◽

Meat Products ◽

Bactericidal Effect ◽

Inhibitory Effect ◽

Control Agent ◽

Control Samples

The aim of this research was to investigate the inhibitory effect of bacteriocin for use as a biological control agent against Listeria monocytogenes in refrigerated meat products. And this bacteriocin was evaluated for their effectiveness as a preservative on pork. The bacteriocin-treated pork was compared with a control pork sample regarding the number of listeria colony count. After 10 days of storage at 4 °C, the population of Listeria monocytogenes was increased from 5.7×105 to 3.7×108 CFU/mL in control samples. In test samples, the population of Listeria monocytogenes underwent a slight increased from 5.7×103 to 6.0×105 CFU/mL. During 10 days of storage, the percentage of growth inhibition ranged from 82.6% to 99.8%, bacteriocin showed their inhibitory effect on Listeria monocytogenes. These results indicated that the studied bacteriocin exhibited bactericidal effect against Listeria monocytogenes strain at refrigerated temperatures, and bacteriocin could be used as antimicrobial agent to preserve the shelf life of refrigerated meat products.

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Growth Inhibition of Dalmatian Toadflax, Linaria dalmatica (L.) Miller, in Response to Herbivory by the Biological Control Agent Mecinus janthinus Germar

Journal of Entomological Science ◽

10.18474/0749-8004-46.3.232 ◽

2011 ◽

Vol 46 (3) ◽

pp. 232-246 ◽

Cited By ~ 9

Author(s):

Marjolein Schat ◽

Sharlene E. Sing ◽

Robert K. D. Peterson ◽

Fabian D. Menalled ◽

David K. Weaver

Keyword(s):

Biological Control ◽

Growth Inhibition ◽

Biological Control Agent ◽

Control Agent ◽

Linaria Dalmatica ◽

Mecinus Janthinus ◽

Dalmatian Toadflax

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Use of Randomly Amplified Polymorphic DNA as a Means of Developing Genus- and Strain-Specific Streptomyces DNA Probes

Applied and Environmental Microbiology ◽

10.1128/aem.66.6.2555-2564.2000 ◽

2000 ◽

Vol 66 (6) ◽

pp. 2555-2564 ◽

Cited By ~ 22

Author(s):

Mark A. Roberts ◽

Don L. Crawford

Keyword(s):

Biological Control ◽

Biological Control Agent ◽

Control Agent ◽

Ribosomal Gene ◽

Dna Polymorphisms ◽

Small Scale ◽

Specific Probe ◽

Randomly Amplified Polymorphic Dna ◽

Streptomyces Lydicus ◽

Soil Dna

ABSTRACT We have analyzed 20 randomly amplified polymorphic DNA (RAPD) primers against 36 Streptomyces strains, including 17 taxonomically undefined strains, 25 nonstreptomycete actinomycetes, and 12 outgroups consisting of gram-positive and -negative species. Most of the primers were useful in identifying unique DNA polymorphisms of all strains tested. We have used RAPD techniques to develop a genus-specific probe, one not necessarily targeting the ribosomal gene, for Streptomyces, and a strain-specific probe for the biological control agent Streptomyces lydicus WYEC108. In the course of these investigations, small-scale DNA isolations were also developed for efficiently isolating actinomycete DNA. Various modifications of isolation procedures for soil DNA were compared, and the reliability and specificity of the RAPD methodology were tested by specifically detecting the S. lydicus WYEC108 in DNA isolated from soil.

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Uji Antagonisme Bacillus cereus terhadap Rhizoctonia solani dan Sclerotium rolfsii

Buletin Tanaman Tembakau Serat & Minyak Industri ◽

10.21082/bultas.v7n1.2015.1-8 ◽

2016 ◽

Vol 7 (1) ◽

pp. 1

Author(s):

Nurul Hidayah ◽

Titiek Yulianti

Keyword(s):

Biological Control ◽

Growth Rate ◽

Rhizoctonia Solani ◽

Biological Control Agent ◽

Sclerotium Rolfsii ◽

Control Agent ◽

Dual Culture ◽

Bacillus Sp ◽

Unfavorable Condition

Jamur Rhizoctonia solani dan Sclerotium rolfsii merupakan kelompok jamur steril (tidak menghasilkan spora) tetapi dapat menghasilkan sklerosia sebagai sumber inokulum primer, dan struktur istirahat jamur yang dapat bertahan selama beberapa tahun di dalam tanah saat kondisi lingkungan kurang menguntungkan. Penggunaan fungisida, fumigasi, dan solarisasi tanah telah digunakan untuk mengendalikan kedua jamur tersebut, namun hasil yang diperoleh masih beragam. Pengendalian hayati dengan menggunakan bakteri Bacillus sp. yang merupakan salah satu kelompok agens hayati patogen diketahui memberikan hasil yang baik pada beberapa tanaman. Penelitian yang bertujuan menguji potensi B. cereus dalam menghambat pertumbuhan jamur R. solani dan S. rolfsii secara in vitro dilaksanakan di Laboratorium Fitopatologi Balittas dengan menggunakan metode dual culture pada media potato dextrose agar (PDA). Miselia jamur R. solani dan S. rolfsii masing-masing berumur 5 hari diambil dengan menggunakan cork borer ukuran 0,5 cm ditanam pada media PDA berhadapan dengan B. cereus dengan jarak 3 cm. Penelitian disusun dalam rancangan acak lengkap dan diulang empat kali. Pengamatan dilakukan terhadap persentase penghambatan pertumbuhan jamur oleh Bacillus sp. dan laju pertumbuhan jamur. Hasil penelitian menunjukkan bahwa Bacillus sp. mampu menghambat pertumbuhan miselia R. solani dan S. rolfsii masing-masing sebesar 68,9% dan 33% pada hari ketiga setelah perlakuan. Keberadaan B. cereus dapat memperlambat laju pertumbuhan R. solani (15,5 mm/24 jam), dibandingkan perlakuan kontrol (tanpa B. cereus) sebesar 19,7 mm/24 jam. Hasil ini menunjukkan bahwa B. cereus dapat menghambat pertumbuhan R. solani dan berpotensi untuk dikembangkan sebagai agens hayati. Rhizoctonia solani and Sclerotium rolfsii (the causal agents of damping off disease on various hosts) are the group of sterile fungi that cannot produce spores. Nevertheless, they produce sclerotia as primary inocula and resting spores when facing unfavorable condition. Several control methods using chemical fungicides and solarization had been conducted, but the results were still inconsistent. In addition, the use of Bacillus sp. as a biological control agent for several plant diseases had provided successful results. Furthermore, the research aimed to evaluate the potency of B. cereus towards R. solani and S. rolfsii in vitro was carried out in the laboratory of phytopathology using dual culture method on PDA medium. Five days of R. solani and S. rolfsii miselia were plugged and inoculated on PDA medium toward B. cereus. The research was arranged by completely randomized design with four replicates. The percentage of fungal inhibition and fungal growth rate were observed. The result showed that B. cereus exhibited mycelial growth inhibition activity of R. solani and S. rolfsii by 68,9% and 33% three days after treatments, respectively. The result also indicated that B. cereus has a potential prospect to be developed as a biological control agent because the bacteria could suspend the growth rate of R. solani.

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