Isolation, characterization and comparison of bacteria from swine faeces and manure storage pits

Abstract

Storage of swine manure is associated with the microbiological production of a variety of odorous chemicals including ammonia, organic acids and alcohols, and sulphides. Although largely the product of microbiological activity, little is known about the microorganisms present in swine manure. In order to gain a better understanding of the types and activities of the microorganisms present, representative strains of microorganisms were isolated from faeces and stored manure slurry, identified, and physiologically characterized. For swine manure slurry samples, total anaerobe colony counts were greatest when a non-selective, habitat simulating medium containing clarified swine manure slurry was used whereas the highest counts for faecal anaerobes were obtained on rumen fluid containing medium. Faecal and slurry samples were also plated onto the appropriate medium containing the antibiotics tetracycline, erythromycin and tylosin (10 μg ml-1, individually) and the proportional counts of organisms capable of growing in the presence of these antibiotics determined. Randomly selected isolates from the highest dilutions were identified by 16 s rDNA sequence analysis, and selected physiological characteristics were determined. The results of these examinations indicate that the predominant culturable microorganisms from these environments are obligately anaerobic, low mol percentage G + C Gram positive bacteria (Firmicutes) who are members of Clostridial, Eubacterial, and Lactobacillus/Streptococcus phylogenetic groups. Isolates similar to Sporomusa and Flexibacter/Cytophaga/Bacteroides (CFB or Bacteroidetes) groups were also obtained. Although similar overall, faecal and slurry samples differed in bacterial composition. Manure slurry samples were dominated by organisms similar to Clostridium coccoides and Enterococcus species whereas the distribution of species present in faeces appeared much broader. Whereas most of the pure cultures could be assigned to known phylogenetic groupings, few could be identified as known species. Examination of some growth and physiological characteristics of faecal and slurry isolates showed these to be primarily carbohydrate fermenters, although some were able to ferment lactate and amino acids. When the ability of manure and faecal isolates to ferment protein, peptides and amino acids was examined, a relatively small percentage of these were able to do so and most of these fermented carbohydrates in addition to the amino acid sources provided. The predominant amino acid fermenters were most closely related to C. coccoides and C. botulinum, but representatives of the Bacteroides, Staphylococcus, Enterococcus and other phylogenetic groups were also found. The results reported here are compared with those obtained from clone libraries prepared from the same environmental samples.