Multicellular behaviour and production of a wide variety of toxic substances support usage of Bacillus subtilis as a powerful biocontrol agent.

Abstract

Intensive cultivation of plants in the monoculture field system in order to feed the continuously growing human population creates a need for their protection from the variety of natural competitors such as: bacteria, fungi, insects as well as other plants. The increase in the use of chemical substances in the 20th century has brought many effective solutions for the agriculture. However, it was extremely difficult to obtain a substance, which would be directed solely against a specific plant pathogen and would not be harmful for the environment. In the late 1900's scientists began trying to use natural antagonisms between resident soil organism to protect plants. This phenomenon was named biocontrol. Biological control of plants by microorganisms is a very promising alternative to an extended use of pesticides, which are often expensive and accumulate in plants or soil, having adverse effects on humans. Nonpathogenic soil bacteria living in association with roots of higher plants enhance their adaptive potential and, moreover, they can be beneficial for their growth. Here, we present the current status of the use of Bacillus subtilis in biocontrol. This prevalent inhabitant of soil is widely recognized as a powerful biocontrol agent. Naturally present in the immediate vicinity of plant roots, B. subtilis is able to maintain stable contact with higher plants and promote their growth. In addition, due to its broad host range, its ability to form endospores and produce different biologically active compounds with a broad spectrum of activity, B. subtilis as well as other Bacilli are potentially useful as biocontrol agents.

Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation

“…Bacillus subtilis, and other members of the genus Bacillus, have long been used as BCAs in agriculture (Nagorska et al, 2007;Ongena and Jacques, 2008). For example, several B. subtilis strains have been successfully employed in pest and disease management programmes (Wulff et al, 2002;Bais et al, 2004;Stein, 2005;Lemessa and Zeller, 2007;Nagorska et al, 2007;Ji et al, 2008;Ongena and Jacques, 2008;Chen et al, 2009a,b). In this work, we isolated wild strains of B. subtilis that demonstrated strong biocontrol activities towards a number of fungal pathogens and a soil-borne bacterial pathogen R. solanacearum in both in vitro assays and experiments performed under greenhouse conditions.…”

“…We therefore expanded our focus to include the production of antimicrobial agents. Bacillus species produce a variety of antimicrobial agents that were proposed to be important in plant biocontrol since these molecules could inhibit growth of certain pathogenic soil microorganisms (Bais et al, 2004;Stein, 2005;Nagorska et al, 2007). To test antimicrobial activities in our wild isolates, we performed in vitro plate assays for the antagonistic activities of the 20 wild strains (from CYBS-1 to CYBS-20) towards nine different plant pathogens (Table 2).…”

“…Bacillus subtilis cells are capable of forming dormant spores that are resistant to extreme conditions and thus can be easily formulated and stored (Piggot and Hilbert, 2004). Bacillus subtilis also produces a variety of biologically active compounds with a broad spectrum of activities towards phytopathogens and that are able to induce host systemic resistance (Bais et al, 2004;Stein, 2005;Butcher et al, 2007;Nagorska et al, 2007;Ongena et al, 2007;Ongena and Jacques, 2008). Various strains of B. subtilis have also been shown to be capable of forming multicellular structures or biofilms (Branda et al, 2001;Hamon and Lazazzera, 2001;Bais et al, 2004).…”

The bacterial lipopeptide iturins induce Verticillium dahliae cell death by affecting fungal signalling pathways and mediate plant defence responses involved in pathogen‐associated molecular pattern‐triggered immunity

“…Members of the Bacillus genus have long been used as BCAs to control plant diseases (Fravel, 2005;Nagorska et al, 2007;Ongena and Jacques, 2008). These bacteria produce a variety of antimicrobial cyclic lipopeptides (LPs), including iturins, fengycins and surfactins (Phae et al, 1990).…”

Endophytic colonisation of Bacillus subtilis in the roots of Robinia pseudoacacia L.

“…Bacillus subtilis is a widespread Gram-positive bacterium, which is non-toxic and harmless to humans, animals and the environment. Many studies have shown that B. subtilis has a close relationship with plants, with the ability to promote plant growth Manjula & Podile 2005;Singh et al 2008;Swain & Ray 2009) and protect plants from pests (Nagó rska et al 2007;Abeysinghe 2009). As growth-promoting endophytic bacteria, some strains of B. subtilis have a synergistic effect on Rhizobiummediated nodulation and nitrogen fixation (Yoshida et al 2006;Rinu & Pandey 2009).…”