Identification of Microbial Populations Associated with Sorghum Fermentation
MBAA TQ doi:10.1094/TQ-47-1-0224-01 |
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E. D. Deenanath (1), S. E. Iyuke (1), and D. Lindsay
(2). 1. School of Chemical and Metallurgical Engineering, University of
the Witwatersrand, Johannesburg, South Africa. 2. Fonterra Research
Centre (FRC), Fitzherbert Science Centres, Palmerston North, New
Zealand.
Abstract
This study reports on the isolation and identification of microbiological
populations that are unique to the University of the Witwatersrand
microbrewery plant during sorghum fermentation. For the fermentation
procedure, the hydrolysate was propagated with either Saccharomyces
cerevisiae strain NRRL Y2084 or Issatchenkia orientalis.
Microbiological procedures such as plate counts and PCR were performed at
the postmashing and postfermentation stages to detect the dominant
microorganisms during sorghum processing when inoculated with starter
cultures. Microbial isolates were characterized by sequencing and
phylogenetic analysis. At the postmashing stage, no microbial contaminants
were found to be associated with the process. At the postfermentation
stage, plate counts showed microbial counts between 5.00 and 8.00 log
CFU/mL. The characterization of microbes isolated at the postfermentation
stage was based on PCR amplification of the 16S and internal transcribed
spacer (ITS) regions. Sequencing results identified the isolates as
Lactococcus lactis, Lactococcus garvieae, Lactobacillus
casei, Enterococcus faecalis, Saccharomyces cerevisiae
strains NCL117 and T8, Saccharomyces paradoxus, Saccharomyces
pastorianus, Saccharomyces kudriavzevii, Issatchenkia orientalis,
and Candida inconspicua.
Keywords: fermentation, hydrolysate, Issatchenkia orientalis,
microorganisms, Saccharomyces cerevisiae
S�ntesis
Este estudio se trata del aislamiento e identificaci�n de poblaciones
microbiol�gicas que son espec�ficas en la cervecer�a artesanal Wits
durante la fermentaci�n de sorgo. En este procedimiento fermentativo se
propag� el hidrolizato bien sea con Saccharomyces cerevisiae (cepa
NRRL Y2084) o Issatchenkia orientalis. Procedimientos
microbiol�gicos tales como contajes en platos Petri y PCR fueron
realizados en las etapas pos-maceraci�n y pos-fermentaci�n para detectar
los microorganismos dominantes durante el procesamiento del sorgo al ser
inoculadas con culturas de arranque. Los microbios aislados fueron
caracterizados mediante an�lisis secuencial y filogen�tico. No se
consiguieron contaminantes microbiol�gicos asociados con el proceso en la
fase posmaceraci�n. En la etapa de pos-fermentaci�n los contajes fueron de
5.00 a 8.00 log UFC/mL. La caracterizaci�n de los microbios aislados en la
etapa de pos-fermentaci�n estivo fundamentada en la amplificaci�n PCR de
las regiones 16S y las regiones espaciadores transcritos internos (ITS).
Los resultados del secuenciamiento identific� los microbios aislados como
Lactococcus lactis, Lactococcus garvieae, Lactobacillus
casei, Enterococcus faecalis, Saccharomyces cerevisiae (cepa
NCL117 y T8), Saccharomyces paradoxus, Saccharomyces
pastorianus, Saccharomyces kudriavezvii, Issatchenkia
orientalis, y Candida inconspicua.
Palabras
claves: fermentaci�n, hidrolizato, Issatchenkia orientalis,
microorganismos, Saccharomyces cerevisiae
