A commensal symbiotic interrelationship for the growth of Symbiobacterium toebii with its partner bacterium, Geobacillus toebii

Abstract

BackgroundSymbiobacterium toebii is a commensal symbiotic thermophile that absolutely requires its partner bacterium Geobacillus toebii for growth. Despite development of an independent cultivation method using cell-free extracts, the growth of Symbiobacterium remains unknown due to our poor understanding of the symbiotic relationship with its partner bacterium. Here, we investigated the interrelationship between these two bacteria for growth of S. toebii using different cell-free extracts of G. toebii.ResultsSymbiobacterium toebii growth-supporting factors were constitutively produced through almost all growth phases and under different oxygen tensions in G. toebii, indicating that the factor may be essential components for growth of G. toebii as well as S. toebii. The growing conditions of G. toebii under different oxygen tension dramatically affected to the initial growth of S. toebii and the retarded lag phase was completely shortened by reducing agent, L-cysteine indicating an evidence of commensal interaction of microaerobic and anaerobic bacterium S. toebii with a facultative aerobic bacterium G. toebii. In addition, the growth curve of S. toebii showed a dependency on the protein concentration of cell-free extracts of G. toebii, demonstrating that the G. toebii-derived factors have nutrient-like characters but not quorum-sensing characters.ConclusionsNot only the consistent existence of the factor in G. toebii during all growth stages and under different oxygen tensions but also the concentration dependency of the factor for proliferation and optimal growth of S. toebii, suggests that an important biosynthetic machinery lacks in S. toebii during evolution. The commensal symbiotic bacterium, S. toebii uptakes certain ubiquitous and essential compound for its growth from environment or neighboring bacteria that shares the equivalent compounds. Moreover, G. toebii grown under aerobic condition shortened the lag phase of S. toebii under anaerobic and microaerobic conditions, suggests a possible commensal interaction that G. toebii scavengers ROS/RNS species and helps the initial growth of S. toebii.

Microbial siderophores and their potential applications: a review

“…It was reported that bacteria isolated from the chambers created by Lewis and Epstein can only grow on a petri plate when they were growing close to the other bacteria isolated from the same environment (Stewart 2012). In an interesting report, Sung and coworkers identified several anaerobic thermophiles in the family Clostridiaceae only when these bacteria were grown in the presence of the extract from Geobacillus toebii (Kim et al 2008(Kim et al , 2011. Toward this direction, Kaeberlein et al (2002) showed that in the course of coculture of microorganisms, one type of microorganism produces siderophore which acts as a growth factor that promotes the growth of other unculturable microorganisms (Kaeberlein et al 2002;Lewis et al 2010).…”

Concepts and Methods to Access Novel Antibiotics from Actinomycetes

“…A different approach to simulate authentic circumstances in the environment comprises co-cultivation of different species derived from the same environment, demonstrating significant influence on the production of secondary metabolites [ 45 , 46 , 47 ]. The main co-cultivation systems can be categorised by the type of technology used in microfluidic systems, petri dish co-culture systems, co-cultures on solid supports, co-culture systems using bioreactors and transwell systems for co-cultivation, allowing asymmetric levels of separation between various numbers of populations [ 39 ].…”

Growing Unculturable Bacteria

“…A number of subsequent efforts to culture other bacteria also revealed plentiful examples of coculture-dependent isolates. The group of Kamagata observed increased growth of the previously uncultured isolate Catellibacterium nectariphilum from a sewage treatment plant in the presence of spent medium from another bacterium (81), while Sung and coworkers identified a number of anaerobic thermophiles in the family Clostridiaceae that were dependent on cell extract from Geobacillus toebii (40,41). In these latter cases, the growth-promoting factors have yet to be identified.…”