The utilisation of used and other fats by fungi
Abstract
English: In 1997, Jeffery and co-workers discovered that when Mucor circinelloides t.
circinelloides CBS 108.16 was cultivated on 30g/1 sunflower oil and 10g/1 sodium
acetate, an improved utilisation of the oil, doubling of the biomass production and
enhancement of the intracellular polyunsaturated y-linolenic acid (GLA) content
occurred as compared to when this fungus was cultivated on only 40g/1 sunflower oil
as sole carbon source. Consequently, the aim of this study became to further
explore this phenomenon (hypothesis) in selected members of the zygomycotan
fungi as well as yeasts when cultivated on various fat and oil substrates in the
presence and absence of acetate. The ultimate aim was to identify those taxa that
can be further explored for the transformation of edible and tall oils to high value
lipids in the presence and absence of acetate. In this study, similar trends were
observed in Mucor circinelloides f circinelloides CBS 108.16 as that found by Jeffery
et al when cultivated on sunflower oil in the presence and absence of acetate. A
similar pattern was also found when this fungus was grown on used cooking oil and
tall oil. The enhancing effect of acetate was not generally observed in the other
fungi and on some other fats and oils tested. Most fungi, including the yeasts, could
grow on fats and oils provided in the presence or absence of acetate. Exceptions to
the rule were MorfierelIa alpina MUFS Mo058 and Lipomyces starkeyi CBS 1807 T
that were unable to grow. Schizosaccharomyces pombe var. pombe CBS 0356 T
could also not grow on linseed oil. The presence of acetate had in many cases a
stimulatory effect on growth. In some cases, the addition of acetate had an
inhibitory effect on growth. With a few exceptions, most mucoralean fungi, when
cultivated on various fats and oils, became oleaginous (i.e. contain ≥ 20% lipids) in
the presence or absence of acetate. However, when these fungi were cultivated on
linseed ail in the presence or absence of acetate they were unable to accumulate
more than 20% lipids according to biomass. Less yeasts became oleaginous when
cultivated on various fat and oil substrates when compared to the mucoralean fungi
tested. The non-oleaginous yeasts i.e. Kluyveromyces, Saccharomyces,
Schizosaccharomyces, Schwanniomyces and Yarrowia became oleaginous when
cultivated on various fats and oils in the presence of acetate. In most mucoralean
fungi and yeasts, the presence of acetate had an effect on cellular lipid content.
The enhancing effect of acetate addition on cellular lipid content was experienced
especially on GongronelIa, Mucor circinelloides t. circinelloides CBS 108.16 and
Thamnostylum when cultivated on various fats and oils. On the other hand, the
addition of acetate had a negative effect on cellular lipid accumulation in some
mucoralean fungi and yeasts. In general, both the mucoralean fungi and yeasts
utilised different fats and oils [(i.e. containing saturated fatty acids (FAs) and
polyunsaturated fatty acids (PUFAs)] as carbon sources in the presence or absence
of acetate. MortierelIa and Lipomyces could not utilise any of these fats and oils.
The presence of acetate had a positive effect on fat and oil utilisation by most
mucaralean fungi and some yeasts. In most cases, a pH increase was observed
probably due to acetic acid utilisation during cultivation. In the presence or absence
of acetate, most mucoralean fungi and yeasts showed a high preference towards the
utilisation of PUFAs present in the residual oil fractions. The addition of acetate had
both a positive and negative effect on the degree of preference towards PUFAs in
the residual lipids. In most cases (in both mucoralean fungi and yeasts) lower
amounts of PUFAs in the cellular lipid fractions in the presence or absence of
acetate were found when compared to the oil substrate fed. This is probably due to
the utilisation of these FAs through β-oxidation for the production of energy. No
general pattern was observed regarding the effect of acetate addition on cellular
PUFA content. Many mucoralean fungi when cultivated on various fats and oils
(except soap skimmings) could produce GLA in the presence or absence of acetate.
All the yeasts in this study could not produce GLA when cultivated on any lipid
substrate in the presence or absence of acetate. This is probably due to the lack of
a ∆6 desaturase enzyme. The addition of acetate improved GLA production in most
mucoralean fungi when cultivated on sunflower oil and used cooking oil. Those
fungi capable of producing GLA in this study should now be explored in the
transformation of edible fats and oils to high value lipids containing GLA. Afrikaans: In 1997 het Jeffery en mede-werkers ontdek dat, wanneer Mucor circinelloides f.
circinelloides CBS 108.16 op 30g/1sonneblomolie en 10g/1natriumasetaat gegroei
word, die olieverbruik verbeter, biomassa produksie verdubbel en die intrasellulêre
y-linoleïensuur (GLS) inhoud verhoog, in vergelyking met wanneer die fungus slegs
op 40g11sonneblomolie as enigste koolstofbron gegroei is. Gevolglik is die doel van
hierdie studie om die verskynsel (hipotese) verder te ondersoek in geselekteerde
lede van die Zygomycota en giste, gegroei op verskeie vet- en oliesubstrate in die
teenwoordigheid en afwesigheid van asetaat. Die uiteindelike doel is om die taksa
te identifiseer wat verder ondersoek kan word vir die transformasie van eetbare en
tallolies na hoëwaarde lipiede in die teenwoordigheid en afwesigheid van asetaat.
In hierdie studie is eenderse tendense waargeneem in Mucor circinelloides f.
circinelloides CBS 108.16 as die gevind deur Jeffery et al wanneer die fungus op
sonneblomolie in die teenwoordigheid en afwesigheid van asetaat gegroei is. In
Soortgelyke patroon is ook gevind wanneer die fungus op gebruikte kookolie en
tallolie gegroei word. Die verhoogde effek van asetaat is nie oor die algemeen
opgemerk in die ander fungi en met sekere getoetsde vette en olies nie.
Uitsonderings op die reël was Mortierella alpina MUFS MoOS8 en Lipomyces
starkeyi CBS 1807 T wat nie kon groei nie. Schizosaccharomyces pombe var.
pombe CBS 0356 T kon ook nie op lynsaadolie groei nie. Die teenwoordigheid van
asetaat het in baie gevalle In stimulerende effek op groei gehad. In sommige
gevalle het die byvoeging van asetaat In inhiberende effek op groei gehad.
Behalwe vir In paar uitsonderings, het die meeste mukoraliese fungi, gegroei op
verskillende vette en olies en oleogeen (d.i. bevat ≥20% lipiede) geraak in die
teenwoordigheid of afwesigheid van asetaat. Wanneer die fungi egter op
lynsaadolie in die teenwoordigheid of afwesigheid van asetaat gegroei is, was hulle
nie instaat om meer as 20% lipiede in hul biomassa te vergader nie. Minder giste
het oleogeen geword wanneer hulle op verskillende vet en oliesubstrate gegroei is.
Die nie-oleogene giste d.i. Kluyveromyces, Saccharomyces, Schizosaccharomyces,
Schwanniomyces en Yarrowia het oleogeen geraak wanneer hulle op verskeie vette
en olies in die teenwoordigheid van asetaat gegroei is. By meeste mukoraliese
fungi en giste het die teenwoordigheid van asetaat In invloed op die sellulêre
lipiedinhoud gehad. Die verhogende effek van asetaat byvoeging op die sellulêre
lipiedinhoud is veralondervind by GongronelIa, Mucor circinelloides f circinelloides
CBS 108.16 en Thamnosfylum wanneer hulle op verskeie vette en olies gegroei is.
Aan die anderkant het die byvoeging van asetaat In negatiewe effek op die sellulêre
lipiedophoping in sommige mukoraliese fungi en giste gehad. Oor die algemeen het
die mukoraliese fungi en giste verskillende vette en olies benut [d.i. met verskillende
versadigde vetsure (VSe) en poli-onversadigde vetsure (POVS)] as koolstofbronne
in die teenwoordigheid of afwesigheid van asetaat. MortierelIa and Lipomyces kon
nie enige van die vette en olies benut nie. Die teenwoordigheid van asetaat het In
positiewe effek op vet en olieverbruik van meeste mukoraliese fungi en sommige
giste gehad. In meeste gevalle is In toename in pH waargeneem, heelwaarskynlik
as gevolg van asynsuurverbruik gedurende groei. In die teenwoordigheid of
afwesigheid van asetaat, het meeste mukoraliese fungi en giste In voorkeur getoon
vir die verbruik van POVS teenwoordig in die residuele oliefraksies. Die byvoeging
van asetaat het beide In positiewe en negatiewe effek op die graad van voorkeur vir
POVS in die residuele lipiede gehad. In die meeste gevalle (by beide mukoraliese
fungi en giste) is laer hoeveelhede POVS in die sellulêre lipiedfraksies gevind as in
die olie van die getoetsde substraat. Dis heelwaarskynlik as gevolg van die gebruik
van die VSe deur β-oksidasie vir die produksie van energie. Geen algemene
patroon is opgemerk aangaande die effek van asetaat byvoeging op sellulêre POVS
inhoud nie. Meeste mukoraliese fungi, wanneer hulle op verskillende vette en olies
gegroei is (behalwe seepskimmings) kon GLS produseer in die teenwoordigheid of
afwesigheid van asetaat. AI die giste in die studie kon nie GLS produseer wanneer
hulle op enige lipiedsubstraat gegroei is nie. Dis heelwaarskynlik as gevolg van die
afwesigheid van 'n ∆6 desaturase ensiem. Die byvoeging van asetaat verbeter GLS
produksie in meeste mukoraliese fungi wanneer hulle gegroei word op
sonneblomolie en gebruikte kookolie. Die fungi wat GLS kon produseer in hierdie
studie, behoort nou ondersoek te word vir die transformasie van eetbare vette en
olies na hoë waarde GLS-bevattende olies.