Isolation, identification, and activityin vitroof killer yeasts againstColletotrichum gloeosporioidesisolated from tropical fruits

Abstract

A total of 580 yeasts strains, isolated from Ceara State of Brasil, were evaluated for their ability to produce killer toxin. Of these strains, 29 tested positive for the killer phenotype and were further evaluated for their ability to control Colletotrichum gloeosporioides germination in vitro. All yeast strains that expressed the killer phenotype were characterized by sequencing the D1/D2 regions of the large subunit of the rRNA gene. Five yeast strains provided a significant reduction in mycelial growth and conidial germination of C. gloeosporioides in vitro, especially Meyerozyma guilliermondii, which was able to reduce the fungal mycelial growth on solid medium (potato dextrose agar (PDA)) by 60% and block 100% of conidia germination in liquid media (potato dextrose broth (PDB)). Filtering and autoclaving the liquid cultures had no effect on the growth of the pathogen. These results indicate the potential use of antagonist yeasts isolated from tropical fruits in the control of anthracnose caused by C. gloeosporioides in papaya. Further elucidation of main mechanisms involved on anthracnose control by these yeasts could be helpful for the development of biocontrol techniques related to the management of this disease in tropical fruits.

Control of phytopathogenic microorganisms of post-harvest in tomato (Lycopersicon esculentum Mill.) with the use of citrus extract

“…It should be noted that the same ones identi ied have been previously reported by Ureña et al [14], and León and Arosemena [15], as the main problems of post-harvest fruit and vegetables, including tomatoes and mango [16,17].…”

Production and Optimization of Killer Toxin in Debaryomyces hansenii Strains

“…Fungi are one of the major factors encountered in postharvest diseases of numerous vegetables and fruits and are considered to be a cause of high economic losses in all over the world [1][2][3] . Nowadays, synthetic fungicides are used generally in postharvest applications and are the most important agents for reducing fungal-based losses.…”

“…Nowadays, synthetic fungicides are used generally in postharvest applications and are the most important agents for reducing fungal-based losses. Nevertheless, the use of synthetic compounds has been progressively restrained because of consumers' no longer want to see toxic or chemical residues in their foods 3 . Furthermore, the increasing occurrence of phytopathogens that are resistant to chemical agents encourages the necessitate to seek for different alternatives for disease control [4][5][6] .…”

“…It is well known that members of certain groups of microorganisms have the ability to produce and secrete extracellular compounds that display antagonistic behaviors against others 7 . Biological control using antagonists seems to be a particularly promising approach to protect different fruits and vegetables from fungal infections 3,8 . Biological agents help reduce the use of chemical-based compounds and this is one of the most important reasons to consider their use.…”

“…In most cases, due to their low or no toxicity to higher organisms they are safer to use. Moreover, they are more stable and less phytotoxic than chemical agents 3,9,10 . Recently, numerous researchers have reported the use of mechanisms of yeast antagonism for the control of fungal-based postharvest losses [11][12][13] .…”