Food signal production of Photorhabdus luminescens inducing the recovery of entomopathogenic nematodes Heterorhabditis spp. in liquid culture

1998 ◽  
Vol 50 (3) ◽  
pp. 369-374 ◽  
Author(s):  
O. Strauch ◽  
R.-U. Ehlers
Keyword(s):  
Liquid Culture ◽  
Entomopathogenic Nematodes ◽  
Photorhabdus Luminescens ◽  
Signal Production ◽  
Food Signal

Carbon dioxide triggers recovery from dauer juvenile stage in entomopathogenic nematodes (Heterorhabditis spp.)

Nematology ◽  
2000 ◽  
Vol 2 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Peter Jessen ◽  
Reiner Luttmann ◽  
Ralf-Udo Ehlers ◽  
Olaf Strauch ◽  
Urs Wyss
Keyword(s):  
Carbon Dioxide ◽  
Liquid Culture ◽  
Spontaneous Recovery ◽  
Photorhabdus Luminescens ◽  
Variable Threshold ◽  
Threshold Response ◽  
Third Stage ◽  
Delayed Recovery ◽  
Food Signal ◽  
Bioreactor Process

AbstractHeterorhabditis spp. (Rhabditida: Nematoda) live in a close symbiosis with the bacterium Photorhabdus luminescens. For biocontrol purposes the nematodes are produced in liquid culture pre-incubated with P. luminescens. The bacteria produce a food signal, inducing dauer juveniles (DJ) to initiate development. In rhabditid nematodes the exit from this developmentally arrested third stage DJ is called recovery. Attempts to produce Heterorhabditis spp. in liquid culture have often failed due to low and delayed recovery of the inoculated DJ. The influence of carbon dioxide as a recovery co-factor was investigated. Increasing concentrations of CO2 enhanced DJ recovery in the presence of the bacterial food signal. The effect could not be related to a decline of the pH caused by increasing CO2 concentrations. On the contrary, at lower pH the DJ recovery decreased. In one experiment a considerable spontaneous recovery was observed in the absence of a food signal. This phenomenon and a variable threshold response of the DJ to CO2 lead to the assumption that they are differently pre-disposed to respond to recovery inducing signals. Providing the results can be confirmed in laboratory scale bioreactors, the control of carbon dioxide during nematode liquid culture can help to improve the bioreactor process technology.Heterorhabditis spp. (Rhabditida: Nematoda) leben in enger Symbiose mit dem Bakterium Photorhabdus luminescens. Für die biologische Bekämpfung werden die Nematoden in Flüssigkulturen vermehrt, die vorher mit P. luminescens inkubiert wurden. Die Bakterien produzieren ein Nahrungssignal, das die Dauerlarven (DJ) veranlasst, ihre Entwicklung wieder aufzunehmen. Bei rhabditiden Nematoden wird das Verlassen des entwicklungsphysiologisch gehemmten Dauerlarvenstadiums als “recovery” bezeichnet. Versuche, Heterorhabditis spp. in Flüssigkultur zu produzieren sind oft aufgrund einer niedrigen oder verspäteten “recovery” gescheitert. Der Einfluß von Kohlendioxid als Einflussfaktor auf die “recovery” wurde untersucht. Zunehmende CO2 Konzentrationen förderten die “recovery” bei Anwesenheit des Nahrungssignals. Einem mit zunehmender CO2-Konzentration fallenden pH-Wert konnte die Wirkung nicht zugeschrieben werden. Im Gegenteil, bei niedrigen pH-Werten nahm die “recovery” ab. In einem Experiment wurde eine spontane “recovery” beobachtet, ohne dass ein Nahrungssignal vorhanden war. Dieses Phänomen und die variable Antwort der Dauerlarven auf gleiche CO2-Konzentrationen lassen den Schluss zu, dass die Dauerlarven unterschiedlich prädisponiert sind in ihrer Reaktion auf die “recovery” induzierenden Signale. Vorausgesetzt die Ergebnisse können in LaborBioreaktoren bestätigt werden, ist die Regelung des Kohlendioxidgehalts während der Nematoden-Flüssigkultur eine Hilfe die Prozesstechnik zu optimieren.

In vivo production of entomopathogenic nematodes suppressed by asymptomatic bacterial contaminants

Nematology ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 917-925
Author(s):  
Akanksha Upadhyay ◽  
Sharad Mohan
Keyword(s):  
Biological Control ◽  
Entomopathogenic Nematodes ◽  
Photorhabdus Luminescens ◽  
Ochrobactrum Anthropi ◽  
Progeny Production ◽  
Bacterial Contaminants ◽  
Significant Difference ◽  
Biological Control Of Insects

Summary Entomopathogenic nematodes (EPN) are excellent biological control agents possessing recycling ability as one of their major attributes. We report the presence of asymptomatic bacteria that can lead to disrupted or low progeny production in Heterorhabditis indica. In a one-to-one in vitro competitive bioassay with contaminants associated with H. indica cuticle, there was a significant suppression in the growth of Sphingomonas koreensis when stressed with the nematode symbiont Photorhabdus luminescens; however, P. luminescens was suppressed when sandwiched between Ochrobactrum anthropi. Bacillus bombysepticus associated with laboratory-reared Galleria when stressed by P. luminescens was significantly suppressed, but not so in the reverse assay. Both O. anthropi and B. bombysepticus were found to be insecticidal to Galleria larvae when fed orally. Tripartite interactive studies on the growth and multiplication of H. indica-P. luminescens symbionts in Galleria larvae, predisposed to S. koreensis, revealed no significant difference initially in the hermaphrodite formation, but subsequently there was a significant decline in the formation of amphimictic females and the final production of infective juveniles. In in vitro studies, none of the contaminants supported the growth and development of axenic H. indica. Adequate precautions should be taken to maintain proper hygiene to eliminate such contaminants while culturing the Galleria and EPN for use in the biological control of insects.

Survival of insect pathogenic and human clinical isolates ofPhotorhabdus luminescensin previously sterile soil

1999 ◽  
Vol 45 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Bruce H Bleakley ◽  
Xiang Chen
Keyword(s):  
Entomopathogenic Nematodes ◽  
Soil Amendments ◽  
Plate Count ◽  
Limited Attention ◽  
Photorhabdus Luminescens ◽  
Bacterial Strains ◽  
Sterile Soil ◽  
Clinical Specimens ◽  
Casamino Acids ◽  
Over Time

Most characterized strains of the bacterium Photorhabdus luminescens are symbionts of entomopathogenic nematodes, whereas other strains have been isolated from human clinical specimens. The ability of P. luminescens strains to survive and grow in soil has received limited attention, with some studies indicating these bacteria have little or no ability to persist in soil. Survival and (or) growth of P. luminescens strains in previously sterilized soil, and examination of different soil amendments on their numbers in soil, have not been previously reported. Entomopathogenic P. luminescens (ATCC 29999) and a human clinical isolate (ATCC 43949) were introduced into a soil that had been sterilized by autoclaving, with or without different soil amendments, and bacterial numbers were estimated over time by viable plate count. In the previously sterilized soil receiving no exogenous amendments, numbers fell drastically over a week's time, followed by an increase in numbers by day 30. Treatments involving the addition of calcium carbonate and gelatin or casamino acids to soil usually resulted in higher bacterial numbers. For some sampling dates and soil treatments, there were statistically significant differences between the numbers of the two bacterial strains recovered from soil. The two strains of P. luminescens used in this study were able to survive and grow after being inoculated into previously sterilized soil.Key words: Photorhabdus luminescens, survival, soil.

scholarly journals Genome sequences of Photorhabdus luminescens strains isolated from entomopathogenic nematodes from southern India

Genomics Data ◽  
2015 ◽  
Vol 6 ◽  
pp. 46-47 ◽  
Author(s):  
Nagesh Mandadi ◽  
Christopher Hendrickson ◽  
Savithri Handanahal ◽  
Thippeswamy Rajappa ◽  
Nikhita Pai ◽  
...  
Keyword(s):  
Entomopathogenic Nematodes ◽  
Southern India ◽  
Photorhabdus Luminescens ◽  
Genome Sequences

Diversity of entomopathogenic nematodes and their symbiotic bacteria in south African plantations and indigenous forests

Nematology ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 355-371 ◽  
Author(s):  
Birhan A. Abate ◽  
Bernard Slippers ◽  
Michael J. Wingfield ◽  
Antoinette P. Malan ◽  
Brett P. Hurley
Keyword(s):  
South Africa ◽  
South African ◽  
Dna Sequences ◽  
Entomopathogenic Nematodes ◽  
Nematode Species ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Time Analysis ◽  
Forestry Plantations ◽  
First Time

Summary The occurrence and diversity of entomopathogenic nematodes (EPN) and their symbiotic bacteria was evaluated in commercial forestry plantations (Eucalyptus spp., Pinus spp. and Acacia mearnsii) and indigenous forests in South Africa. EPN were most prevalent in A. mearnsii plantations, accounting for 60.7% of the isolates, while indigenous forests, plantations of Pinus spp. and Eucalyptus spp. accounted for 35.7, 3.6 and 0% of the isolates, respectively. DNA sequences of the internal transcribed spacer (ITS) and D2-D3 28S rDNA regions were used to identify the nematode species. Four Steinernema spp. were identified, including S. citrae, S. sacchari, two undescribed species, as well as Heterorhabditis bacteriophora and H. baujardi. Heterorhabditis baujardi is reported from South Africa for the first time. Analysis of 16S rRNA of the bacteria confirmed the presence of at least three Xenorhabdus species from Steinernema isolates and two subspecies of Photorhabdus luminescens from Heterorhabditis species.

Physico-chemical properties and mode of action of a signal from the symbiotic bacterium Photorhabdus luminescens inducing dauer juvenile recovery in the entomopathogenic nematode Heterorhabditis bacteriophora

Nematology ◽  
2001 ◽  
Vol 3 (8) ◽  
pp. 849-853 ◽  
Author(s):  
Ralf-Udo Ehlers ◽  
Jens Aumann
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Chemical Properties ◽  
Symbiotic Bacterium ◽  
Heterorhabditis Bacteriophora ◽  
Juvenile Stage ◽  
Food Sources ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Physico Chemical

AbstractRecovery in entomopathogenic nematodes is the exit from the dauer juvenile stage. It is a response to environmental queues signalling the presence of food sources (e.g., insect haemolymph). The bacterium Photorhabdus luminescens excretes a signal which also induces recovery of its symbiotic Heterorhabditis bacteriophora dauer juveniles. This bacterial signal is composed of at least two compounds with different polarity. The symbiotic bacteria also secrete an antagonistic signal which inhibits nematode recovery. The recovery-inducing signal compounds have a molecular mass of less than 20 kDa and are negatively charged. The data indicate that at least one compound is smaller than 5 kDa. The bacterial signal triggers by receptor binding, the first step in a recovery-inducing muscarinic signalling pathway.

Effect of agitation speed on the density of bacteria Photorhabdus luminescens and the population dynamics of nematodes Heterorhabditis megidis in liquid culture

2021 ◽  
Vol 95 ◽  
Author(s):  
D. Tumialis ◽  
A. Mazurkiewicz ◽  
I. Skrzecz
Keyword(s):  
Liquid Culture ◽  
Agitation Speed ◽  
Infective Juvenile ◽  
Photorhabdus Luminescens ◽  
Maximum Increase ◽  
Persistent Problem ◽  
Liquid Cultures ◽  
Heterorhabditis Megidis ◽  
Dynamics Of Population ◽  
The Impact

Abstract Liquid culture is the most scalable technology for the industrial production of entomopathogenic nematodes. Variability of the recovery after inoculation into cultures of Photorhabdus luminescens remains a persistent problem in the mass production of Heterorhabditis sp. In order to enhance infective juvenile (IJ) recovery and improve nematode population management, we analysed the correlation between the nematode Heterorhabditis megidis (strain KV – 136) development in liquid cultures, the density of bacteria of P. luminescens and the culture agitation speed. Analyses focused on the impact of different agitation speeds (160 rpm and 200 rpm) on the dynamics of population growth of H. megidis in liquid cultures at constant biotic and abiotic parameters (initial dose of nematodes introduced to the culture 2300 IJs/ml, temperature 25°C, the number of bacterial colonies 0.3 × 107/ml). The performed experiments showed that the agitation speed of 200 rpm favourably affected the density of bacteria of P. luminescens (24.14 × 107/ml). High density of bacteria at this agitation speed resulted in an earlier (on the fifth day of the culture) maximum increase in the number of hermaphroditic individuals (1239.6 H/ml) than in the culture at an agitation speed of 160 rpm.

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