Acid tolerant bacterium Bacillus amyloliquefaciens MBNC retains biocontrol efficiency against fungal phytopathogens in low pH

2022 ◽  
Vol 204 (2) ◽  
Author(s):  
Naimisha Chowdhury ◽  
Dibya Jyoti Hazarika ◽  
Gunajit Goswami ◽  
Unmona Sarmah ◽  
Shrutirupa Borah ◽  
...  
2021 ◽  
Author(s):  
Naimisha Chowdhury ◽  
Dibya Jyoti Hazarika ◽  
Gunajit Goswami ◽  
Unmona Sarmah ◽  
Shrutirupa Borah ◽  
...  

Abstract Soil pH conditions have important consequences for microbial community structure, their dynamics, ecosystem processes, and interactions with plants. Low soil pH affects the growth and functional activity of bacterial biocontrol agents which may experience a paradigm shift in their ability to act antagonistically against fungal phytopathogens. In this study, the antifungal activity of an acid tolerant soil bacterium Bacillus amyloliquefaciens MBNC was evaluated under low pH and compared to its activity in neutral pH conditions. Bacterial supernatant from three-day old culture grown in low pH conditions were more effective against fungal pathogens. B. amyloliquefaciens MBNC harboured genes involved in the synthesis of secondary metabolites of which surfactin homologues, with varying chain length (C11 – C15) were identified through High-Resolution Mass Spectroscopy. The pH of the medium influenced the production of these metabolites. Surfactin C15 was exclusive to the extract of pH 4.5; production of iturinA and surfactin C11 was detected only in pH 7.0 while, surfactin C12, C13 and C14 were detected in extracts of both the pH conditions. The secretion of phytohormones viz. Indole Acetic Acid (IAA) and Gibberellic Acid (GA) by B. amyloliquefaciens MBNC were detected in higher amount in neutral condition compared to acidic condition. Although, secretion of metabolites and phytohormones in B. amyloliquefaciens MBNC was influenced by the pH condition of the medium, the isolate retained its antagonistic efficiency against several fungal phyto-pathogens under acidic condition.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gabriella Boisen ◽  
Julia R. Davies ◽  
Jessica Neilands

Abstract Background In caries, low pH drives selection and enrichment of acidogenic and aciduric bacteria in oral biofilms, and development of acid tolerance in early colonizers is thought to play a key role in this shift. Since previous studies have focussed on planktonic cells, the effect of biofilm growth as well as the role of a salivary pellicle on this process is largely unknown. We explored acid tolerance and acid tolerance response (ATR) induction in biofilm cells of both clinical and laboratory strains of three oral streptococcal species (Streptococcus gordonii, Streptococcus oralis and Streptococcus mutans) as well as two oral species of Actinomyces (A. naeslundii and A. odontolyticus) and examined the role of salivary proteins in acid tolerance development. Methods Biofilms were formed on surfaces in Ibidi® mini flow cells with or without a coating of salivary proteins and acid tolerance assessed by exposing them to a challenge known to kill non-acid tolerant cells (pH 3.5 for 30 min) followed by staining with LIVE/DEAD BacLight and confocal scanning laser microscopy. The ability to induce an ATR was assessed by exposing the biofilms to an adaptation pH (pH 5.5) for 2 hours prior to the low pH challenge. Results Biofilm formation significantly increased acid tolerance in all the clinical streptococcal strains (P < 0.05) whereas the laboratory strains varied in their response. In biofilms, S. oralis was much more acid tolerant than S. gordonii or S. mutans. A. naeslundii showed a significant increase in acid tolerance in biofilms compared to planktonic cells (P < 0.001) which was not seen for A. odontolyticus. All strains except S. oralis induced an ATR after pre-exposure to pH 5.5 (P < 0.05). The presence of a salivary pellicle enhanced both acid tolerance development and ATR induction in S. gordonii biofilms (P < 0.05) but did not affect the other bacteria to the same extent. Conclusions These findings suggest that factors such as surface contact, the presence of a salivary pellicle and sensing of environmental pH can contribute to the development of high levels of acid tolerance amongst early colonizers in oral biofilms which may be important in the initiation of caries.


2004 ◽  
Vol 50 (6) ◽  
pp. 109-114 ◽  
Author(s):  
D.V. Savant ◽  
D.R. Ranade

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.


2018 ◽  
Vol 7 (18) ◽  
Author(s):  
Matthew J. Meier ◽  
Annette Dodge ◽  
Lee A. Beaudette

Bacillus amyloliquefaciens NRRL 942 is a Gram-positive bacterium with several potential industrial uses. We have sequenced the whole genome of this organism to assist in understanding the biological mechanisms that might modulate human health or environmental risk in the event of its release into the environment.


2011 ◽  
Vol 78 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Doug Bertel ◽  
John Peck ◽  
Thomas J. Quick ◽  
John M. Senko

ABSTRACTThe mineralogical transformations of Fe phases induced by an acid-tolerant, Fe(III)- and sulfate-reducing bacterium,Desulfosporosinussp. strain GBSRB4.2 were evaluated under geochemical conditions associated with acid mine drainage-impacted systems (i.e., low pH and high Fe concentrations). X-ray powder diffractometry coupled with magnetic analysis by first-order reversal curve diagrams were used to evaluate mineral phases produced by GBSRB4.2 in media containing different ratios of Fe(II) and Fe(III). In medium containing Fe predominately in the +II oxidation state, ferrimagnetic, single-domain greigite (Fe3S4) was formed, but the addition of Fe(III) inhibited greigite formation. In media that contained abundant Fe(III) [as schwertmannite; Fe8O8(OH)6SO4·nH2O], the activities of strain GBSRB4.2 enhanced the transformation of schwertmannite to goethite (α-FeOOH), due to the increased pH and Fe(II) concentrations that resulted from the activities of GBSRB4.2.


2019 ◽  
Vol 203 ◽  
pp. 117-124 ◽  
Author(s):  
Lei Liu ◽  
Jing Liu ◽  
Xiaoting Liu ◽  
Chengwei Dai ◽  
Zexin Zhang ◽  
...  

Biotecnia ◽  
2018 ◽  
Vol 20 (2) ◽  
pp. 59-64
Author(s):  
José Luis García Hernández ◽  
María Cristina Ruíz Alvarado ◽  
Pablo Preciado Rangel ◽  
Alejandra Nieto-Garibay ◽  
Bernardo Murillo-Amador ◽  
...  

Capsicum annuum var. aviculare is one of the most extremely hot chilies, measuring between 50,000 and 100,000 Scoville Units. In the present work we studied the growth and development of chiltepin (Mazocahui), under field conditions, inoculated with previously selected and cultivated native strains of Bacillus amyloliquefaciens and Azospirillum halopraeferens. The seed was inoculated by the vacuum technique, and later at 34, 120, 180 and 210 days after germination. A drip irrigation system with a salinity (TDS) = 0.8 ppt was used. The results show that germination is significantly favored by the promoter effect caused by the beneficial bacteria. These inoculants increased some parameters of growth and development. We found significant differences regarding the control for the total weight and length of root and stem of the plants, as well as the total content of proteins, and in some parts of the plant analyzed as stem and leaf. Both bacteria increased fruit yield in the Mazocahui genotype. Our findings suggest that the application of strains of Bacillus amyloliquefaciens and Azospirillum halopraeferens, influence the increase in yield of Capsicum annuum var. aviculare, under field conditions. In addition, the data show the usefulness of the inoculation of chiltepin seed for agricultural producers in semi-arid areas where salinity is a problem.


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