For a study, it was determined that Bifidobacteria were a common type of bacteria found in the adult human gut microbiota and were thought to be advantageous to the host’s health. Following ingestion of a mix of short-chain galactooligosaccharides, long-chain fructooligosaccharides, and acidic oligosaccharides from pectin hydrolysate (GFP), the dynamics and functional activity of bifidobacteria from the digestive tract of four people were studied. The percentage of overall bifidobacteria was not considerably changed, but there were significant species-specific changes in all individuals throughout time, indicating a dynamic bifidobacterial population. A clone library-based microarray containing the genomes of several bifidobacteria was used to expose the bifidobacterial transcriptome within the fecal population, providing insight into their functional activities. Total RNA from the fecal microbial community was hybridized to the microarray, and 310 clones were chosen for sequencing, revealing genes from a variety of functional groups with high metabolic activity. While GFP ingestion had no effect on the overall change in gene expression, it did have a significant effect on 82 genes. The majority of the predicted genes were involved in plant-derived carbohydrate metabolism, housekeeping tasks including DNA replication and transcription, and membrane transport of a variety of substrates like sugars and metals, as well as amino acid metabolism. Other genes involved in transport, nucleotide metabolism, amino acid metabolism, environmental data processing, cellular functions, and signaling were discovered. General metabolism, glycan metabolism, energy metabolism, lipid metabolism, and cell surface metabolism all had a reduced number of genes implicated. The findings back with the theory that bifidobacteria primarily rely on indigestible polysaccharides for energy and cellular component production.