Properties and attempted culture of Pasteuria penetrans, a bacterial parasite of root‐knot nematode (Meloidogyne javanica)

Abstract

When they were subjected to a range of physical and chemical treatments, spores of Pasteuria penetrans showed properties similar to those of other endospore‐forming bacteria. The spores did not take up some stains, were resistant to desiccation and sonication and showed extrusion of spore contents (‘spore popping’) on prolonged exposure to 0.1% KMnO4 in 0.3 n HNO3. Calcium and dipicolinic acid (DPA) were present at concentrations of 0.28% and 0.96% of the spore dry weight respectively, giving a Ca: DPA molar ratio of 1.2. The infectivity of P. penetrans spores was reduced to a low level after heating at 100°C for 5 min, but spore attachment was not markedly affected by heating at 100°C for 15 min. Evidence for the presence of catalase in P. penetrans spores was equivocal because the low levels of catalase activity observed in spore suspensions may have been due to contamination from catalase‐positive nematode tissue. When P. penetrans spores were exposed to a range of substances known to act as germinants for spores of Bacillus spp., germination or loss of refractility was not observed by phase microscopy. In vitro culture of P. penetrans was attempted by inoculating either spores or vegetative mycelial bodies onto a diverse range of simple and complex media and incubating them in aerobic, reduced oxygen, anaerobic and increased CO2 environments. Signs of spore germination or growth of vegetative stages were never observed.

Phylogenetic position of the North American isolate of Pasteuria that parasitizes the soybean cyst nematode, Heterodera glycines, as inferred from 16S rDNA sequence analysis.

“…in vitro have not been successful (Bishop & Ellar, 1991 ;Williams et al, 1989). As a result, the taxonomy of the genus Pasteuria has been marked by a series of errors and confusion (Sayre & Starr, 1989), as it relies mainly on morphological, developmental and pathological characteristics including the size and shape of the sporangium and endospore, ultrastructure, life cycle and host range (Davies et al, 1990 ;Giblin-Davis et al, 1990 ;Metchnikoff, 1888 ;Noel & Stanger, 1994 ; N. Atibalentja and others 1989 ; Sayre et al, 1991a, b ;Sturhan et al, 1994).…”

Exploiting Genomics to Understand the Interactions Between Root-Knot Nematodes and Pasteuria penetrans

“…Although this production method is good enough to produce sufficient spores for the use of small scale growers, large growers will require levels of mass production that would be better suited to an in vitro culturing method. Attempts to grow Pasteuria in vitro (Williams et al 1989;Bishop and Ellar 1991) have produced very limited success. Bishop and Ellar (1991) produced two media, one of which would sustain vegetative growth and another led to the production of endospores, but because at no point did the bacteria grow exponentially they were never able to produce enough for commercial application.…”

Pasteuria penetrans and Its Parasitic Interaction with Plant Parasitic Nematodes

“…The vegetative stage is very fragile and prone to lysis. Of the published attempts to culture P. penetrans in vitro (Williams et al 1989;Bishop and Ellar 1991) the best that has been achieved has simply been to create conditions suitable for the ball mycelia extracted from a female nematode to go through an apparently pre-programmed and limited number of divisions and differentiate into sporangia and produce spores. There is no reliable report to date of any sustained vegetative growth or triggering of germination.…”