Hello, my name is Hanseniaspora uvarum (aka Kloeckera apiculata)

Eureka, we are finally back to spoilage yeasts. Today, I would like to introduce another spoilage yeast called Hanseniaspora uvarum (anamorph Kloeckera apiculata). A very acid-tolerant yeast that can be found close to everywhere and is involved in various natural fermentations such as wine and even certain beer styles. Lets have a closer look at K. apiculata and some fermentations associated with this yeast.

Where do I work?

K. apiculata is present in early grape juice, cacao, coffee fermentation, malting barley, cider fermentation, spoiled figs, tomatoes, canned black cherries, can be isolated from fresh strawberries, black currants, wine grapes and various other fruits, fruit juices and fruit syrups [Pitt and Hocking, 2009, Kurtzman et al, 2011]. Furthermore, K. apiculata could be isolated from soil, fruit flies, caterpillars and even sea water (Florida USA) [Kurtzman et al, 2011]. In summary, K. apiculata is very abundant in nature. Lets have a look at some fermentations in more detail.

A study to investigate the microflora associated with wet Coffea arabica fermentation (pulped coffee is left to ferment under water) in Tanzania identified K. apiculata [Masoud et al, 2004]. The general idea is that K. apiculata, together with other yeasts, are involved in the degradation of the pulp of the coffee beans by secreting pectinases (pectin is a polysaccharide in plants found to give structural integrity). Making it possible to get the coffee bean without any pulp remainders. Another study investigating the microflora of wet fermenting Coffea arabica in Mexico could not identify K. apiculata [Avallone et al, 2001]. Same results performed on dry fermentation (pulped coffee is left to ferment exposed to air) of Coffea arabica in Brazil where the authors could not find any K. apiculata [Silva et al, 2008]. I don’t believe that K. apiculata is not present in Mexico and Brazil. I think it might be another example of the techniques used to identify yeasts may make a difference. Some techniques (especially molecular techniques such as PCR) can be more sensitive than agar plates. Furthermore, molecular techniques can pick up non-viable yeasts (as the DNA is still present) whereas one would miss these yeasts on agar plates as the yeasts are not viable (not growing) anymore.

Moving on to Irish Cider where K. apiculata is the predominant yeast in the first fermentation phase before Saccharomyces cerevisiae takes over [Morrissey et al, 2004]. In this case, the authors could identify the apples as the source for K. apiculata. Interesting to notice is the fact that the maturation phase is dominated by Brettanomyces/Dekkera (you are welcome, fellow Brett hunters).

What about beer?

Compared to some previous featured spoilage yeasts, Kloeckera apiculata can be found in beer. Very similar to the previous mentioned natural fermentations, K. apiculata is involved in a natural beer fermentation: The Belgian Lambics. After leaving the wort cool in a coolship and inoculation/mixing in tanks, the Lambic fermentation starts within a couple of days [Fig 1]. Beginning with an increase of Enterobacteriaceae and K. apiculata within the first days [van Oevelen et al, 1977]. Right before Saccharomyces sp. take over. What K. apiculata exactly contributes to the flavor composition of Lambics (and Geuze) is not really well understood. One study shows a minor impact on fatty acids and ester production where K. apiculata can increase C8, C10 and C12 fatty acids during fermentation [Spaepen M et al, 1978].

Fig 1: Microflora evolution in Lambic fermentation taken from van Oevelen et al, 1977

Although it is commonly accepted that K. apiculata is involved in Lambic fermentations, very recent studies to investigate the microflora at Cantillon as well as an American Coolship Ale facility (Allagsh?) don’t mention K. apiculata in their result section [Bokulich et al, 2012, Spitaels F et al, 2014]. Beside all these results, one can further pose the question how K. apiculata can even get into the wort in the first place? Maybe from the wine barrels?

What is so special about me?

K. apiculata is one of the dominant yeasts in several early natural fermentation stages. Beside that, the yeast seems to have some interesting enzymes such as beta-D-glucosidase and beta-D-Xylosidase which are key enzymes to release aromatic compounds in winemaking [Kurtzman et al, 2011].

Not only are enzymes interesting but flocculation seems to be an interesting research topic as well. As previously discussed, premature flocculation can lead to premature end of a fermentation. Studies showed that K. apiculata is able to pull down a poor flocculent S. cerevisiae strain [Sosa et al, 2008]. The authors mention a possible application such as removing any natural S. cerevisiae yeasts by co-flocculation from the grape must with K. apiculata (before fermentation). Then adding a well-defined S. cerevisiae culture for the main fermentation.

Where can you find me?

In theory and taking all the various sources into consideration where one can find K. apiculata, isolating K. apiculata from various natural sources should be rather easy. Furthermore to notice, K. apiculata is not an important human pathogen although isolates exist [Kurtzman et al, 2011].

Some biochemical stats about me for yeast ranchers

Fig 2: Kloeckera apiculata (sample received from SuiGeneris)

Data summarized from Kurtzman et al (2011).

Systematic name:	Hanseniaspora uvarum (anamorph Kloeckera apiculata)
Synonyms:	There are a lots of accepted synonyms for this yeasts. Just some examples: Hanseniaspora apiculata, Kloeckera brevis
Growth on YM agar:	Cell morphology:	Apiculate, spherical to ovoid, 1.5 -5 µm x 2.5-11.5 µm [Fig 2]
	Clustering:	Occurring as single cells or pairs
	Pseudohyphae:	May be observed
	Pellicle formation:	Not described
Fermentation:	Glucose:	Positive
	Galactose:	Negative
	Sucrose:	Negative
	Maltose:	Negative
	Lactose:	Negative
	Raffinose:	Negative
	Trehalose:	Negative

Since K. apiculata is negative for maltose fermentation and actually only capable of fermenting glucose, it is very unlikely that a single K. apiculata beer fermentation would work (as mainly maltose is present in wort). K. apiculata however should work very well with Cidre and other natural fruit juices where the most dominant sugar is glucose. That’s everything I got for Kloeckera apiculata.

Bibliography

• Avallone S, Guyot B, Brillouet JM, Olguin E, Guiraud JP (2001) Microbiological and Biochemical Study of Coffee Fermentation. Current Microbiology, Vol 42, p 252-256
• Bokulich NA, Bamforth CW, Mills DA (2012) Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale. PLoS ONE, Vol 7(4)
• Kurtzman CP, Fell JW, Boekhout T (2011) The Yeasts, a Taxonomic Study. Volume 1. Fifth edition. Elsevier (Link to sciencedirect)
• Masoud W, Cesar LB, Jespersen L, Jakobsen M (2004) Yeast involved in fermentation of Coffea arabica in East Africa determined by genotyping and by direct denaturating gradient gel electrophoresis. Yeast, Vol 21(7), p 549-56
• Morrissey WF, Davenport B, Querol A, Dobson ADW (2004) The role of indigenous yeasts in traditional Irish cider fermentations. Journal of Applied Microbiology, Vol 97, p647-655
• Pitt JI, Hocking AD (2009) Fungi and Food Spoilage. Springer Science & Business Media
• Silva CF, Batista LR, Abreu LM, Dias ES, Schwan RF (2008) Succession of bacterial and fungal communities during natural coffee (Coffea arabica) fermentation. Food Microbiology, Vol 25, p 951-957
• Spaepen M, van Oevelen D, Verachtert H (1978) Fatty Acid And Esters Produced During The Spontaneous Fermentation Of Lambic And Gueuze. J. Inst. Brew, Vol 84, p 278-282
• Spitaels F, Wieme AD, Janssens M, Aerts M, Daniel H-M, van Landscoot A, de Vuyst L, Vandamme P (2014) The Microbial Diversity of Traditional Spontaneously Fermented Lambic Beer. PLoS ONE, Vol 9(4)
• Sosa OA, de Nadra MCM; Farias ME (2008) Behaviour of Kloeckera apiculata flocculent strain in coculture with Saccharomyces cerevisiae. Food Technology And Biotechnology, Vol 4, p 413-418
• Van Oevelen D, Spaepen M, Timmermans P, Verachtert D (1977) Microbiological Aspects Of Spontaneous Wort Fermentation In The Production Of Lambic And Gueuze. J. Inst. Brew, Vol 83, p 356-360