Yeast diversity of Ghanaian cocoa bean heap fermentations

Abstract

The fermentation of the Theobroma cacao beans, involving yeasts, lactic acid bacteria, and acetic acid bacteria, has a major influence on the quality of the resulting cocoa. An assessment of the microbial community of cocoa bean heap fermentations in Ghana resulted in 91 yeast isolates. These were grouped by PCR-fingerprinting with the primer M13. Representative isolates were identified using the D1/D2 region of the large subunit rRNA gene, internal transcribed spacer sequences and partial actin gene sequences leading to the detection of 15 species. Properties of importance for cocoa bean fermentation, namely sucrose, glucose, and citrate assimilation capacity, pH-, ethanol-, and heat-tolerance, were examined for selected isolates. Pichia kudriavzevii (Issatchenkia orientalis), Saccharomyces cerevisiae, and Hanseniaspora opuntiae formed the major components of the yeast community. Hanseniaspora opuntiae was identified conclusively for the first time from cocoa fermentations. Among the less frequently encountered species, Candida carpophila, Candida orthopsilosis, Kodamaea ohmeri, Meyerozyma (Pichia) caribbica, Pichia manshurica, Saccharomycodes ludwigii, and Yamadazyma (Pichia) mexicana were not yet documented from this substrate. Hanseniaspora opuntiae was preferably growing during the earlier phase of fermentation, reflecting its tolerance to low pH and its citrate-negative phenotype, while no specific temporal distribution was recognized for P. kudriavzevii and S. cerevisiae.

Kinetic Analysis of Strains of Lactic Acid Bacteria and Acetic Acid Bacteria in Cocoa Pulp Simulation Media toward Development of a Starter Culture for Cocoa Bean Fermentation

“…They are responsible for liquefying the pulp through depectinization, which reduces pulp viscosity, and for fermentative production of ethanol from carbohydrates under anaerobic (due to tight packing of the beans), acidic (presence of citric acid in the pulp), and carbohydrate-rich (sucrose, glucose, and fructose in the pulp) conditions. Recent studies on Ghanaian cocoa bean heap fermentations show that Hanseniaspora opuntiae is the predominant yeast during the initial phase of fermentation (7,10,18,19). Also, Pichia kudriavzevii, Pichia membranifaciens, and Saccharomyces cerevisiae have been reported to play a role in the fermentation of cocoa beans (1,7,10,27).…”

“…Recent studies on Ghanaian cocoa bean heap fermentations show that Hanseniaspora opuntiae is the predominant yeast during the initial phase of fermentation (7,10,18,19). Also, Pichia kudriavzevii, Pichia membranifaciens, and Saccharomyces cerevisiae have been reported to play a role in the fermentation of cocoa beans (1,7,10,27). As the pulp drains away, air penetrates into the fermenting mass, which creates ideal conditions for the growth of bacteria.…”

“…Information on the functioning of yeasts during cocoa bean fermentation is widely available (1,7,10,19,28). Fewer studies focus on the functioning of LAB and AAB in addition to species diversity and identification (1,4,5,18,28).…”

The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

“…Acetate then diffuses into the beans (2)(3)(4), where it initiates a cascade of chemical and biochemical reactions leading to precursor molecules for cocoa flavor (2,5,6). Potential substrates for AAB are lactate and ethanol, which are individually produced by lactic acid bacteria (LAB; mainly Lactobacillus fermentum) and yeasts (diverse yeasts such as Saccharomyces cerevisiae, Hanseniaspora opuntiae, and Candida krusei), respectively, during the fermentation process (6)(7)(8)(9)(10)(11)(12). Hereby, the degradation of lactate by AAB is desired, since the remaining lactate may provide an off flavor in the final cocoa product (11,13,14).…”

Preliminary Analysis of Sugar Supplementation on Alcoholic Fermentation by <i>Meyerozyma guilliermondii</i>

“…Kluyveromyces marxianus [19], [20], Pichia kudriavzevii [21], [22], Dekkera bruxellensis [23], Zygosaccharomyces bailii [24]. Meyerozyma guilliermondii, a telemorph of Candida guilliermondii or wine yeast is one of such promising non Saccharomyces yeasts obtained from environmental samples with unique biotechnological applications and biological control potential [25], [26], [27], [28]. This yeast specie is known for its ease of consumption of xylose, naturally converting it to xylitol [29], [30].…”