title: Identification of the most abundant lactobacillus species in the crop of 1- and 5-week-old broiler chickens.
abstract: Bacteria from crops of 1- and 5-week-old broiler chickens fed with two brands (diets A and B) of wheat-based diets were isolated on Lactobacillus-selective medium and identified (n = 300) based on partial 16S rRNA gene sequence. The most abundant Lactobacillus species were L. reuteri (33%), L. crispatus (18.7%), and L. salivarius (13.3%). Regardless of farm and feed, L. reuteri was the most abundant species (P < 0.005) in the crops of the younger chickens. However, the amount of L. reuteri was significantly reduced in the crops of the 5-week-old chickens regardless of the feed (P = 0.016). The diversity of L. reuteri isolates was studied by fatty acid analysis, and the 94 L. reuteri isolates could be arranged into several clusters. The nisin sensitivities of the L. reuteri isolates were determined because nisin is a candidate coccidiostat. Sensitive isolates were found more frequently in younger chickens (77%) than in 5-week-old chickens (23%), whereas chickens fed with commercial feed B had a higher proportion of nisin-resistant isolates (73%) than did chickens fed with feed A (45%). Nisin-resistant strains are potential candidates for adjunct cultures for maintaining L. reuteri in its natural niche in the crop and are potential targets for genetic engineering with nisin-selectable food-grade vectors. The diversity of the L. reuteri population suggested that one should consider including several strains representing different clusters and nisin resistance phenotypes in candidate probiotic feed supplements for chickens.
authors.affiliation: Department of Applied Chemistry and Microbiology, Viikinkaari 9, FI-00014 University of Helsinki, Finland. per.saris@helsinki.fi.
authors.forename: Hanan T
authors.initials: HT
authors.lastname: Abbas Hilmi
authors.forename: Anu
authors.initials: A
authors.lastname: Surakka
authors.forename: Juha
authors.initials: J
authors.lastname: Apajalahti
authors.forename: Per E J
authors.initials: PE
authors.lastname: Saris
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D044822:Biodiversity; D002645:Chickens / Q000382:microbiology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D041981:Gastrointestinal Tract / Q000382:microbiology*; D007778:Lactobacillus / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D009561:Nisin / Q000494:pharmacology; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014908:Triticum / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S; D009561:Nisin