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Isolation and characterization of yeasts associated with plants growing in heavy-metal- and arsenic-contaminated soils.

Authors
  • Ramos-Garza, Juan1, 2
  • Bustamante-Brito, Rafael1
  • Ángeles de Paz, Gabriela3
  • Medina-Canales, Ma Gabriela3
  • Vásquez-Murrieta, María Soledad4
  • Wang, En Tao2
  • Rodríguez-Tovar, Aída Verónica1
  • 1 a Laboratorio de Micología General y Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas (ENCB), Instituto Politécnico Nacional (IPN), Prolongación de Carpio y Plan de Ayala s/n, 11340 Mexico City, Mexico.
  • 2 b Laboratorio de Ecología Microbiana, Departamento de Microbiología, ENCB, IPN, 11340 Mexico City, Mexico.
  • 3 c Laboratorio de Nematología Agrícola, Departamento de Parasitología, ENCB, IPN, 11340 Mexico City, Mexico.
  • 4 d Laboratorio de Microbiología Industrial, Departamento de Microbiología, ENCB, IPN, 11340 Mexico City, Mexico.
Type
Published Article
Journal
Canadian Journal of Microbiology
Publisher
Canadian Science Publishing
Publication Date
April 2016
Volume
62
Issue
4
Pages
307–319
Identifiers
DOI: 10.1139/cjm-2015-0226
PMID: 26936448
Source
Medline
Keywords
License
Unknown

Abstract

Yeasts were quantified and isolated from the rhizospheres of 5 plant species grown at 2 sites of a Mexican region contaminated with arsenic, lead, and other heavy metals. Yeast abundance was about 10(2) CFU/g of soil and 31 isolates were obtained. On the basis of the phylogenetic analysis of 26S rRNA and internal transcribed spacer fragment, 6 species were identified within the following 5 genera: Cryptococcus (80.64%), Rhodotorula (6.45%), Exophiala (6.45%), Trichosporon (3.22%), and Cystobasidium (3.22%). Cryptococcus spp. was the predominant group. Pectinases (51.6%), proteases (51.6%), and xylanases (41.9%) were the enzymes most common, while poor production of siderophores (16.1%) and indole acetic acid (9.67%) was detected. Isolates of Rhodotorula mucilaginosa and Cystobasidium sloffiae could promote plant growth and seed germination in a bioassay using Brassica juncea. Resistance of isolates by arsenic and heavy metals was as follows: As(3+) ≥ 100 mmol/L, As(5+) ≥ 30 mmol/L, Zn(2+) ≥ 2 mmol/L, Pb(2+) ≥ 1.2 mmol/L, and Cu(2+) ≥ 0.5 mmol/L. Strains of Cryptococcus albidus were able to reduce arsenate (As(5+)) into arsenite (As(3+)), but no isolate was capable of oxidizing As(3+). This is the first study on the abundance and identification of rhizosphere yeasts in a heavy-metal- and arsenic-contaminated soil, and of the reduction of arsenate by the species C. albidus.

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