Isolation and characterization of bacteria and yeasts from contaminated soil

Plant growth promoting (PGP) bacteria and yeasts play an important role in bioremediation processes. Thirty bacterial and ten yeast isolates were obtained from PAH and PCB contaminated soil with an aim of determining the presence of PGP mechanisms (production of ammonia, indoleacetic acid, siderophores and solubilization of inorganic phosphate). As a result, three bacterial (Serratia liquefaciens, Micrococcus sp. and Serratia sp.) and two yeast isolates (Candida utilis and Candida tropicalis) were recognized as PGP strains. Among them, Serratia sp. showed the highest indole production (25.5 ?g/ml). Analyses of metal tolerance (Cu+2, Cr+6 and Ni+2) revealed that Serratia liquefaciens, Micrococcus sp., Serratia sp. and Candida tropicalis were capable to tolerate significant concentration of metals. As a result of this study several bacterial and yeast strains were attributed as potential plant growth promoters which can be applied in future remediation activities and environmental quality improvements.

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Influence of fluorescent Pseudomonas on the growth of Mimosa scabrella seedlings

Pesquisa Florestal Brasileira ◽

10.4336/2021.pfb.41e201902078 ◽

2021 ◽

Vol 41 ◽

Author(s):

Daniceli Barcellos ◽

Vanessa Gisele Dambros ◽

Yanka Rocha Kondo ◽

Andressa Vasconcelos Flôres ◽

Jussara Cristina Stinghen ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promoting Rhizobacteria ◽

Luria Bertani ◽

Nodule Formation ◽

Growth Promoters ◽

Fluorescent Pseudomonas ◽

Plant Growth Promoters ◽

Plant Growth Promoting ◽

South Of Brazil ◽

Potential Use

Bracantiga (Mimosa scabrella Benth) is a native leguminous specie from the south of Brazil, with great potential for commercial use. It can be used to recover degraded areas due to their fast growth, high adaptability and root nodule formation capacity. One alternative to reduce fertilization costs of seedlings production, are the plant growth promoting rhizobacteria. The fluorescent group of Pseudomonas is common at several plant rhizosphere. The objective of this work was to assess the growth stimulus of fluorescent Pseudomonas isolates at bracatinga seedlings. The seeds were inoculated with three bacterial isolates (CBSAL14, CBSAL18 and CBSAL05), genetically identified as Pseudomonas sp. They were previously grown in 50 mL of Luria Bertani medium for 48 h and then the seeds were submerged for 30 min in the suspensions. Subsequently, they were sown in tubes containing sterilized commercial substrate and kept in greenhouse for five months. From 61 days after sowing, seedling height and stem diameter were measured monthly. The CBSAL14 and CBSAL18 isolates promoted promoted increase in growth of seedlings height of inoculated individuals compared to control, suggesting their potential use as plant growth promoters.

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

Frontiers in Microbiology ◽

10.3389/fmicb.2021.738058 ◽

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.

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