First report of fission yeast Schizosaccharomyces pombe (Lindner)

The following article is the first description of the yeast species Schiz. pombe and is published in the German brewery weekly Wochenschrift für Brauerei (Volume 10, pages 1298-1300) in 1893.

This NIH library translation (NIH-95-272) from German into English was provided by Ted Crump, translator. Copyright restrictions apply. This translation is for exclusive use of Frans Hochstenbach, and has been edited by Frans Hochstenbach and Norman Hu.

Schizosaccharomyces pombe sp. nov., a New Ferment

(With illustration.)

by P. Lindner

(Report from the [Brewery] Association Laboratory.)

Schizosaccharomyces pombe was isolated from millet beer, sent from East Africa to Germany in the year 1890 with the assistance of Major von Wissman, and further cultivated to a pure culture. According to the report of Dr. Saare (s. Wochenschr. 1890, p. 534), the [0.5 liter sample of] millet beer [which had been in transit between Sansibar and its destination in Germany from March 26 until April 29, 1890] consisted of "a light brown liquid, which had thick grayish-white settlings, covering half the bottle, with mixed-in pieces and remnants from the millet used. The taste was acidulous, similar to that of sour leaven from the distillery, rotten, and not particularly pleasant. [Fresh millet beer, however, was drunk with pleasure by the Germans, who considered it a healthy and refreshing beverage, according to Dr. Saare.] Microscopic examination of the settlings revealed many angular wide-clefted starch granules, many paste flakes, fiber remnants, and millet husk parts, brown-colored mycelium remnants of molds, very numerous wild yeasts of all varieties, some still viable, partly very small cells, partly long tubular cells (the latter often with 3 or more ascospores), and many bacteria, mostly short and very thin bacilli, and less frequently long and thick bacilli. In attempts thus far to isolate the ferment, it has only been possible to obtain a mold in pure form, since many bacteria hindered the pure cultivation."

That is as far as the report goes. Later Herr Ziedler, who at that time was working under my supervision in the Association Laboratory, nevertheless was able to eliminate the bacteria and obtain the yeast in pure form with the use of beerwort made acidic with tartar. Morphologically, this yeast represents a thoroughly peculiar type; it justifiably can be called fission yeast, because, besides by means of spores, they only reproduce by means of fission. Here, there is no budding at all, such as we find in brewer's yeast. The cell form shows somewhat of a correspondence to Oidium lactis [currently classified as Geotrichum candidum, a common mold of milk]; they are cylindrical, rounded on the ends, and highly fluctuating in size.

In exhausted nutrient medium the cells become ever shorter, until they finally reach the length of ordinary brewer's yeast cells. In this condition, mistaking them in a superficial observation would therefore not be impossible. The appearance of a transverse wall precedes the fission of a cell, which at the same time begins to divide from outside to inside. Therewith a constriction begins, which leads to the complete separation of the two segments. At the separation site the membrane, which naturally is still very tender, is very pliable to pressure coming from inside; here, very soon, an apical growth also takes place. The membrane bulges forward very sharply and grows into a tube until the size of the original cell is reached approximately. Initially, the new piece is usually somewhat thinner than the old. Later, however, this difference is balanced out, and at the transition site a ring-shaped indentation is recognizable, the boundary between the old and new membranes.

Under certain conditions, such as with limited [fresh] air access, one can observe growth of many cells into very long tubes in which a number of transverse walls appear [i.e., pseudo-hyphal growth] without, however, an immediate breakdown into an equal number of segments [as is the case with mycelia of Oidium lactis]. When breaking apart, the two segments often still remain connected at one point around which they rotate like a hinge.

Cells may also grow out laterally. Although this occurs for the most part right underneath the transverse wall, the formation of lateral branches also can occur on cells that have no transverse walls at all. Usually, a fission and segmentation of cells is first observed here on the lateral branch, specifically on the apex.

The transverse walls usually have their origin in the middle of the cells, but can also be distributed very irregularly; in exceptional cases, they are also obliquely attached. At the places where lateral branches originate, it can also occur that one transverse wall sits on top of another.

The two endpoints of a cell, for the most part, have a different appearance; one end is rounded off, the other surrounded by a sharply-drawn ring wall, which encloses the newly formed membrane portion that already is raised up in a club shape. Sometimes in a cell preparation we notice cells that almost have the appearance of dumb-bells; these have developed from segmented cells that were bordered on both sides by transverse walls. After separation the bilateral end surfaces simultaneously bulged forward. If the cell was only bordered by one transverse wall, then later only one such spherical swelling forms. The entirety then resembles a [floral] pistil. A not infrequent form of the cell, particularly at the time of spore formation, resembles a 'mezza luna' [i.e., a two-handled crescent-shaped knife].

With regard to the cell content, this for the most part exhibits a homogeneous or fine-granular quality with accumulation of granules in places. In the oidium-like cells there are always only two such granule groups, which are near the poles. Before the appearance of the transverse walls one can observe here and there an accumulation of such granules into a more or less thick, rather strongly refractive layer, in whose middle a clear membrane then suddenly appears.

The spore formation occurs relatively readily in this yeast, even in hanging wort drops, when the vegetative reproduction has come to a standstill. In one case the first spores were seen after 7 days, and after 9 days they already were represented abundantly. No traces on the gypsum could yet be found, even after 3 days; here the gypsum block is not a suitable foundation for the spore culture. In a 15-week-old gelatin culture approx. 15% of the cells had formed spores in the settlings of the liquefied gelatin. It should be emphasized especially that even in fermenting liquid, whether it be wort or dextrose solution, spore formation already begins in the settlings at the end of the main fermentation. The number of spores alternates between 1-4. The phenomenon is striking that in those vegetations which have taken their origin from wort drops of a single cell, the spore formation often runs its course in cells lying together in groups, which previously could not be distinguished from the other cells that subsequently remained spore-free. The germination of the spore begins with a swelling and with formation of a germ tube of almost the same thickness. The spore membrane is not burst in the germination, but rather makes a transition into the new membrane at the site in question. As soon as the germ tube has reached approximately the length of an ordinary vegetative cell, it divides by means of a transverse wall and breaks up into two halves. The mother cell [ascus] membrane is for the most part burst apart; in other cases, however, the spores pass through an opening before they swell. In the 'mezza luna'-like cells the spores usually are so distributed that the middle segment remains free of spores. The spores are usually very lustrous.

The left side of the drawing shows vegetations from wort, some of which are in various stages of development. The oidium-like cells hanging loosely in a chain originated from an already exhausted culture.

[Hand drawn illustration of fission yeast]

Explanation of the figure: The right side shows us a large number of spore-bearing cells, some of which are in the stage of spore germination. The groups linked by arrows belong together. The more advanced development stage is directly recognizable. The cells are in part taken from gelatin cultures. The thread-like mature cells creeping toward the left grew in a wort drop that was embedded between the glass slide, cover slip and vaseline ring.

Sown in wort, the fission yeast produced a rather vigorous fermentation; the 'kräusen' [i.e., dense foam on top of the beer wort after fermentation] are rather compact and almost free of hop resin precipitations. An evenly thick yeast layer lies on the bottom, as with a bottom yeast. Dextrose and raw sugar solutions are likewise fermented. I will publish the results of the fermentation experiments at a later opportunity.

No skin formations were observed either in the wort or in the liquid gelatin. [In contrast, Oidium lactis forms a heavily wrinkled skin on milk.]

In an inoculation smear on wort gelatin, the fission yeast forms a compact coating, which is somewhat finely sprinkled over the surface; it has a similar quality in a so-called giant colony. Fig. 10 from Plate II in No. 27 of the current year of the Wochenschrift gives a picture of it, albeit not with the desirable clarity. In the growth on gelatin the stronger longitudinal growth of the cells is an almost general phenomenon. The liquefaction of the nutrient gelatins occurs in the course of 5-6 weeks. The declining cells gradually take on a pathologic appearance and also die earlier than cells which, for example, dried previously on the glass with the gelatin. In one case the cells of the latter type proved still viable after 9 months, judging from the microscopic appearance, while the culture below the liquefied, but rather thickened gelatin had already died.

I chose the name Schizosaccharomyces on the one hand to give a meaningful expression to the essential difference that exists from a morphologic standpoint in relation to the genus Saccharomyces, and, on the other hand, to take into account the common characteristics such as spore formation and fermentation capacity.

The addition of the word Pombe was analogous to Saccharomyces kefyr, for example [kefir is fermented cow's milk]. Although certainly other wild yeasts, including a Torula species, were found in the millet beer (no detailed study of the species involved here has occurred), nevertheless our organism is the characteristic component of this vegetation.

If we compare the budding process of ordinary brewer's yeast with the peculiar mode of reproduction of our organism, we find in part some close relationships. Thus, for example, in the latter the new germ tube often breaks away through a transv!!!#!####&&&&&&#######!!!!!!!!###&&&&(((((**((&&(&#&###!!!!!!!###&&((((******,*,*((*((&&#####!!!!!#&((((**,**,,.,,,,,*,*(((&&&##!!!!!!!!!!#&&((((**,,,,,,..,...,,.,,,**(&&&###!!!!!!!##&&(*((((*,,,,,.1.1.1......,,**(((&&&##!!!!!!!!!&&(*(*****,,,...1111.111..1331...,**(((&##!!!!!!#&(((*,,**,,,.1.13311313311333331....,,,*(####!!!!!&&(*(*,,,,,.....13337555555753557733311.,(&#####!!!!##&(**,,,,,..1.11153579755599997555575111.1,(&#####!!!!!!#(****,...1.113135795799799799975779757533.*(&&&##!!!!!!#&(((**..11113335579<9<<<<><@<><999<779997311**(&####!!!!!!##&(**,...1..13555<<9><<<>@B@>@B@>B>>@<9>>99551,*(&&&#!!!!!!#&&***,,,.13357777979>@@>@BGGGIEIGIEB@><>>9<9731,,*(&&##!!!!!#&***,,....11557<<9><>@@EIGLRRRRRNPIGE@>>>@@<<751.,,((&#!#!!!!!##&**,,.,...1359<<>>EB@@GNNPRW\jg`^YURIEB@@B@>><7753.,((&&##!!!!##&(*,*,.1.1157<>>@@BEGPYc`^egjvxsnccYPLGB@@@><<975113,*&&&###!!!#&&(**.,,1333799>@BGGGNWcqxsx}xsnl`WNGEBB@@><775311.,*(&###!!!!!!!#&(*,,,.113379>@BGBGIUel`UIEBEB@>>99953111.*(&&&#!!!!!!!!!!!!###(*,,,,.5557<<>@@GILWqscRLIGBBB>><95351.,,**&(&##!!!!!!!!!!!!!!!##&(,,,.11377<9<>@EGLYxv`RLIEB@><99975311.,,*((&&##!!!####!#!!#!!!!####&&*,...337599<9<@EI`zŻŻjWIIGE@>>>9957511.,,**(((&!!!!##!##&&&##&######!!!##!#&(*,11135579<9<>@EL\zåeRIE@>@><9797533.,,,,*,(&&