Importance of Biofilm Formation in Plant Growth Promoting Rhizobacterial Action

2010 ◽  
pp. 81-95 ◽  
Author(s):  
Gamini Seneviratne ◽  
M. L. M. A. W. Weerasekara ◽  
K. A. C. N. Seneviratne ◽  
J. S. Zavahir ◽  
M. L. Kecskés ◽  
...  
Keyword(s):  
Plant Growth ◽  
Biofilm Formation ◽  
Plant Growth Promoting ◽  
Growth Promoting

scholarly journals Bacillus velezensisWall Teichoic Acids Are Required for Biofilm Formation and Root Colonization

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Zhihui Xu ◽  
Huihui Zhang ◽  
Xinli Sun ◽  
Yan Liu ◽  
Wuxia Yan ◽  
...  
Keyword(s):  
Plant Growth ◽  
Biofilm Formation ◽  
Root Colonization ◽  
Molecular Networks ◽  
Model Organisms ◽  
Bacillus Velezensis ◽  
Content Type ◽  
Plant Growth Promoting ◽  
Colonization Process ◽  
Growth Promoting

ABSTRACTRhizosphere colonization by plant growth-promoting rhizobacteria (PGPR) along plant roots facilitates the ability of PGPR to promote plant growth and health. Thus, an understanding of the molecular mechanisms of the root colonization process by plant-beneficialBacillusstrains is essential for the use of these strains in agriculture. Here, we observed that ansfpgene mutant of the plant growth-promoting rhizobacteriumBacillus velezensisSQR9 was unable to form normal biofilm architecture, and differential protein expression was observed by proteomic analysis. A minor wall teichoic acid (WTA) biosynthetic protein, GgaA, was decreased over 4-fold in the Δsfpmutant, and impairment of theggaAgene postponed biofilm formation and decreased cucumber root colonization capabilities. In addition, we provide evidence that the major WTA biosynthetic enzyme GtaB is involved in both biofilm formation and root colonization. The deficiency in biofilm formation of the ΔgtaBmutant may be due to an absence of UDP-glucose, which is necessary for the synthesis of biofilm matrix exopolysaccharides (EPS). These observations provide insights into the root colonization process by a plant-beneficialBacillusstrain, which will help improve its application as a biofertilizer.IMPORTANCEBacillus velezensisis a Gram-positive plant-beneficial bacterium which is widely used in agriculture. Additionally,Bacillusspp. are some of the model organisms used in the study of biofilms, and as such, the molecular networks and regulation systems of biofilm formation are well characterized. However, the molecular processes involved in root colonization by plant-beneficialBacillusstrains remain largely unknown. Here, we showed that WTAs play important roles in the plant root colonization process. The loss of thegtaBgene affects the ability ofB. velezensisSQR9 to sense plant polysaccharides, which are important environmental cues that trigger biofilm formation and colonization in the rhizosphere. This knowledge provides new insights into theBacillusroot colonization process and can help improve our understanding of plant-rhizobacterium interactions.

scholarly journals Functional and Genetic Diversity of Bacteria Associated with the Surfaces of Agronomic Plants

Plants ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 91 ◽  
Author(s):  
Basharat Ali
Keyword(s):  
Genetic Diversity ◽  
Plant Growth ◽  
Bacillus Cereus ◽  
Biofilm Formation ◽  
Host Plants ◽  
Human Pathogens ◽  
Positive Interaction ◽  
Auxin Production ◽  
Plant Growth Promoting ◽  
Growth Promoting

The main objective of this study was to evaluate the genetic diversity and agricultural significance of bacterial communities associated with the surfaces of selected agronomic plants (carrot, cabbage and turnip). The bacterial diversity of fresh agricultural produce was targeted to identify beneficial plant microflora or opportunistic human pathogens that may be associated with the surfaces of plants. Bacterial strains were screened in vitro for auxin production, biofilm formation and antibiotic resistance. 16S rRNA gene sequencing confirmed the presence of several bacterial genera including Citrobacter, Pseudomonas, Pantoea, Bacillus, Kluyvera, Lysinibacillus, Acinetobacter, Enterobacter, Serratia, Staphylococcus, Burkholderia, Exiguobacterium, Stenotrophomonas, Arthrobacter and Klebsiella. To address the biosafety issue, the antibiotic susceptibility pattern of strains was determined against different antibiotics. The majority of the strains were resistant to amoxicillin (25 µg) and nalidixic acid (30 µg). Strains were also screened for plant growth-promoting attributes to evaluate their positive interaction with colonized plants. Maximum auxin production was observed with Stenotrophomonas maltophilia MCt-1 (101 µg mL−1) and Bacillus cereus PCt-1 (97 µg mL−1). Arthrobacter nicotianae Lb-41 and Exiguobacterium mexicanum MCb-4 were strong biofilm producers. In conclusion, surfaces of raw vegetables were inhabited by different bacterial genera. Potential human pathogens such as Bacillus cereus, Bacillus anthracis, Enterobacter cloacae, Enterobacter amnigenus and Klebsiella pneumoniae were also isolated, which makes the biosafety of these vegetable a great concern for the local community. Nevertheless, these microbes also harbor beneficial plant growth-promoting traits that indicated their positive interaction with their host plants. In particular, bacterial auxin production may facilitate the growth of agronomic plants under natural conditions. Moreover, biofilm formation may help bacteria to colonize plant surfaces to show positive interactions with host plants.

scholarly journals An Osmoregulatory Mechanism Operating through OmpR and LrhA Controls the Motile-Sessile Switch in the Plant Growth-Promoting BacteriumPantoea alhagi

2019 ◽  
Vol 85 (10) ◽  
Author(s):  
Shuyu Li ◽  
Hong Liang ◽  
Zhiyan Wei ◽  
Haonan Bai ◽  
Mengyun Li ◽  
...  
Keyword(s):  
Plant Growth ◽  
Osmotic Stress ◽  
Biofilm Formation ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Osmoregulatory Mechanism

ABSTRACTAdaptation to osmotic stress is crucial for bacterial growth and survival in changing environments. Although a large number of osmotic stress response genes have been identified in various bacterial species, how osmotic changes affect bacterial motility, biofilm formation, and colonization of host niches remains largely unknown. In this study, we report that the LrhA regulator is an osmoregulated transcription factor that directly binds to the promoters of theflhDC,eps, andopgGHoperons and differentially regulates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production, synthesis of osmoregulated periplasmic glucans (OPGs), biofilm formation, and root colonization of the plant growth-promoting bacteriumPantoea alhagiLTYR-11Z. Further, we observed that the LrhA-regulated OPGs control RcsCD-RcsB activation in a concentration-dependent manner, and a high concentration of OPGs induced by increased medium osmolarity is maintained to achieve the high level of activation of the Rcs phosphorelay, which results in enhanced EPS synthesis and decreased motility inP. alhagi. Moreover, we showed that the osmosensing regulator OmpR directly binds to the promoter oflrhAand promotes its expression, whilelrhAexpression is feedback inhibited by the activated Rcs phosphorelay system. Overall, our data support a model wherebyP. alhagisenses environmental osmolarity changes through the EnvZ-OmpR two-component system and LrhA to regulate the synthesis of OPGs, EPS production, and flagellum-dependent motility, thereby employing a hierarchical signaling cascade to control the transition between a motile lifestyle and a biofilm lifestyle.IMPORTANCEMany motile bacterial populations form surface-attached biofilms in response to specific environmental cues, including osmotic stress in a range of natural and host-related systems. However, cross talk between bacterial osmosensing, swimming, and biofilm formation regulatory networks is not fully understood. Here, we report that the pleiotropic regulator LrhA inPantoea alhagiis involved in the regulation of flagellar motility, biofilm formation, and host colonization and responds to osmotic upshift. We further show that this sensing relies on the EnvZ-OmpR two-component system that was known to detect changes in external osmotic stress. The EnvZ-OmpR-LrhA osmosensing signal transduction cascade is proposed to increase bacterial fitness under hyperosmotic conditions inside the host. Our work proposes a novel regulatory mechanism that links osmosensing and motile-sessile lifestyle transitions, which may provide new approaches to prevent or promote the formation of biofilms and host colonization inP. alhagiand other bacteria possessing a similar osmoregulatory mechanism.

scholarly journals Prospecting Endophytic Bacteria Endowed With Plant Growth Promoting Potential Isolated From Camellia sinensis

2021 ◽  
Vol 12 ◽  
Author(s):  
Shabiha Nudrat Hazarika ◽  
Kangkon Saikia ◽  
Atlanta Borah ◽  
Debajit Thakur
Keyword(s):  
Plant Growth ◽  
Biofilm Formation ◽  
Endophytic Bacteria ◽  
Growth Promotion ◽  
Growth Promoters ◽  
Plant Growth Promoters ◽  
Plant Growth Promoting ◽  
Promote Plant Growth ◽  
Growth Promoting

Endophytes are well-acknowledged inoculants to promote plant growth, and extensive research has been done in different plants. However, there is a lacuna about the endophytes associated with tea clones and their benefit to promote plant growth. The present study focuses on isolating and characterizing the beneficial endophytic bacteria (EnB) prevalent in commercially important tea clones cultivated in North Eastern India as plant growth promoters. Diversity of culturable EnB microbiome, in vitro traits for plant growth promotion (PGP), and applicability of potent isolates as bioinoculant for in vivo PGP abilities have been assessed in the present study. A total of 106 EnB identified as members of phyla Proteobacteria, Firmicutes, and Actinobacteria were related to 22 different genera and six major clusters. Regarding PGP traits, the percentage of isolates positive for the production of indole acetic acid, phosphate solubilization, nitrogen fixation siderophore, ammonia, and 1-aminocyclopropane-1-carboxylic acid deaminase production were 86.8, 28.3, 78.3, 30.2, 95.3, and 87.7, respectively. In total, 34.0, 52.8, and 17.0% of EnB showed notable production of hydrolytic enzymes like cellulase, protease, and amylase, respectively. Additionally, based on the bonitur score, the top two isolates K96 identified as Stenotrophomonas sp. and M45 identified as Pseudomonas sp. were evaluated for biofilm formation, motility, and in vivo plant growth promoting activity. Results suggested strong biofilm formation and motility in K96 and M45 which may attribute to the colonization of the strains in the plants. Further in vivo plant growth promotion experiment suggested sturdy efficacy of the K96 and M45 as plant growth promoters in nursery condition in commercial tea clones Tocklai vegetative (TV) TV22 and TV26. Thus, this study emphasizes the opportunity of commercialization of the selected isolates for sustainable development of tea and other crops.

Aplikasi Bacillus subtilis pada beberapa Bahan Organik terhadap Pertumbuhan dan Produksi Tanaman Cabai Rawit (Capsicum frutescens L.)

2020 ◽  
Vol 21 (1) ◽  
pp. 14-19
Author(s):  
Praptiningsih Gamawati Adinurani ◽  
Sri Rahayu ◽  
Nurul Fima Zahroh
Keyword(s):  
Bacillus Subtilis ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Capsicum Frutescens ◽  
Plant Growth Promoting ◽  
Growth Promoting

Mikroba Bacillus subtilis merupakan agen pengendali hayati mempunyai kelebihan sebagai Plant Growth Promoting Rhizobacteria (PGPR) yaitu dapat berfungsi sebagai biofertilizer, biostimulan, biodekomposer dan bioprotektan. Tujuan penelitian mengetahui potensi B. subtilis dalam merombak bahan organik sebagai usaha meningkatkan ketersediaan bahan organik tanah yang semakin menurun. Penelitian menggunakan Rancangan Petak Terbagi dengan berbagai  bahan organik sebagai petak utama (B0 = tanpa bahan organik, B1 = kotoran ayam,  B2 = kotoran kambing, B3 = kotoran sapi) dan aplikasi B.subtilis sebagai anak petak (A0 = 0 cc/L, A1 = 5cc/L, A2 = 10 cc/L, Pengamatan meliputi variabel tinggi tanaman, indeks luas daun, jumlah buah per tanaman, berat buah per tanaman, dan bahan organik tanah. Data pengamatan  dianalisis ragam  menggunakan  Statistical Product and Service Solutions (SPSS) versi 25 dan dilanjutkan dengan uji Duncan untuk mengetahui signifikansi perbedaan antar perlakuan. Hasil penelitian menunjukkan tidak terdapat interaksi antara bahan organik kotoran ternak dan konsentrasi B. subtilis terhadap semua variabel pengamatan. Potensi B. subtilis sangat baik dalam mendekomposisi bahan organik yang ditunjukkan dengan peningkatan bahan organik, dan hasil terbaik pada kotoran  sapi (B3) dan konsentrasi B. subtilis 15 mL/L masing-masing sebesar 46.47 % dan 34.76 %. Variabel pertumbuhan tidak berbeda nyata kecuali tinggi tanaman dengan pertambahan tinggi paling banyak pada pemberian kotoran kambing sebesar 170.69 %.

Isolation and identification of plant growth-promoting bacteria associated with tall fescue

2009 ◽  
pp. 211-216 ◽  
Author(s):  
J. Monk ◽  
E. Gerard ◽  
S. Young ◽  
K. Widdup ◽  
M. O'Callaghan
Keyword(s):  
New Zealand ◽  
Plant Growth ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Plant Growth Promoting Bacteria ◽  
Beneficial Bacteria ◽  
Isolation And Identification ◽  
Naturally Occurring ◽  
Plant Growth Promoting ◽  
Growth Promoting

Tall fescue (Festuca arundinacea) is a useful alternative to ryegrass in New Zealand pasture but it is slow to establish. Naturally occurring beneficial bacteria in the rhizosphere can improve plant growth and health through a variety of direct and indirect mechanisms. Keywords: rhizosphere, endorhiza, auxin, siderophore, P-solubilisation

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