| dc.description.abstract | The need for probiotics as an alternative to antibiotics (Antibiotic Growth
Promoters/AGPs) to stimulate growth in chickens is increasingly pressing,
especially following the ban on the use of AGPs due to their potential resistance to
pathogenic microbes. One type of microorganism that can be used and has potential
as a probiotic is yeast. Yeast is known to have advantages over bacteria and can
benefit chicken health. Research on the use of yeast as a probiotic agent in chickens
is still minimal, so further exploration of local isolates with potential probiotic
agents is needed. The purpose of this study was to evaluate the characteristics of
probiotic yeast isolated from the chicken digestive tract and its ability to help
maintain chicken health.
Yeast was isolated from the digestive tract and faeces of free-range chickens.
A total of 16 yeast isolates were obtained with varying morphology and cell size.
Hemolysis testing was performed on the 16 yeast isolates using blood agar. Thirteen
isolates were ?-hemolytic (non-pathogenic), one isolate was a-hemolytic, and two
isolates did not grow on blood agar. Furthermore, eight isolates out of 13 isolates
showed good resistance to bile salt stress, and of the eight isolates, six isolates were
able to survive acidic pH stress. The autoaggregation test showed that all selected
isolates could aggregate well at 4 hours of incubation, while the coaggregation test
with Salmonella Typhimurium showed that there was one isolate that could not
aggregate, as well as one isolate with a good aggregation percentage, namely isolate
UBB1, with a coaggregation percentage of 54%. Of the six isolates that could
aggregate, continued with antibacterial tests and proteolytic and amylolytic tests,
the results were only one isolate (UBB1) that showed antibacterial activity with an
inhibition index of 2,09 against Salmonella Typhimurium ATCC14028. Molecular
identification carried out on isolate UBB1 confirmed it as Pichia kudriavzevii with
a bootstrap value of 100. Therefore, P. kudriavzevii UBB1 is considered potential
and promising. This confirms that local yeast can be developed as a probiotic and
can be used to support poultry health and productivity. | |
