Cyanide Production by Rhizobacteria and Potential for Suppression of Weed Seedling Growth

Abstract

Rhizobacteria strains were characterized for ability to synthesize hydrogen cyanide and for effects on seedling root growth of various plants. Approximately 32% of bacteria from a collection of over 2000 isolates were cyanogenic, evolving HCN from trace concentrations to > 30 nmoles/mg cellular protein. Cyanogenesis was predominantly associated with pseudomonads and was enhanced when glycine was provided in the culture medium. Concentrations of HCN produced by rhizobacteria were similar to exogenous concentrations inhibiting seedling growth in bioassays, suggesting that cyanogenesis by rhizobacteria in the rhizosphere can adversely affect plant growth. Growth inhibition of lettuce and barnyardgrass by volatile metabolites of the cyanogenic rhizobacteria confirmed that HCN was the major inhibitory compound produced. Our results suggest that HCN produced in the rhizospheres of seedlings by selected rhizobacteria is a potential and environmentally compatible mechanism for biological control of weeds.

Growth promotion of wheat seedlings by Exiguobacterium acetylicum 1P (MTCC 8707) a cold tolerant bacterial strain from the Uttarakhand Himalayas

“…HCN production by rhizospheric bacteria has been variably viewed, while it is considered benefi cial from the biocontrol point of view, it is considered detrimental due to its interference with the cytochrome P 450 system, of certain plants [35]. In this study, seed bacterization did not have a detrimental effect on plant growth and development.…”

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

“…Contrary to the role of HCN as abiocontrol agent, several researchers concluded that HCN is hardly a universal biocontrol agent and even caused phytotoxic effects in most in vitro experiments (Alström and Burns, 1989;Pal et al, 2000;Kremer and Souissi, 2001;Rudrappa et al, 2008;Blom et al, 2011). In a recent study by Rijavec and Lapanje (2016) have shown that there is no correlation between the amount of HCN produced by a particular strain and its ability to inhibit the growth of phytopathogenic bacteria or fungi.…”

Isolation and characterization of mutants of Pseudomonas maltophila PM-4 altered in chitinolytic activity and antagonistic activity against root rot pathogens of clusterbean (Cyamopsis tetragonoloba)

“…Chitinases are produced by a number of microorganisms such as Bacillus, Pseudomonas, Serratia, Stenotrophomonas, Streptomyces and Vibrio; and is one of the mechanism that has been implicated in biocontrol of fungal diseases 6 . Other probable mechanism includes production of antibiotics viz: 2-4-diacetylphloroglucinol, pyrrolnitrin, siderophores, HCN and induced systemic resistance (ISR) 7,8,9,10,11 . Bacterial strains with altered chitinolytic activity have been produced by mutagenesis in Serratia plymuthica or by introduction of chitinase gene into heterologous strains 12,13 .…”