Isolation and Characterization of Bacteria from Free Ranging Sheep and Goats Tolerant to Toxic Compound(s) in Acacia Angustissima leaves
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Date
2014-01
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Addis Ababa Universty
Abstract
The study was conducted at the ILRI-Debre Zeit Research Station to screen the various
extracts of Acacia anglls/issillla for evidence of toxicity using mixed and pure cultures of
bacteria, and to isolate bacteria capable of tolerating or detoxifYing the toxic principle. Gas
production was llsed as an index of fermentation to screen the amino acid, non-basic,
chloroform and ethanol extracts from A. anglls/issillla leaves for toxicity to mixed and pure
rumen microbes. RlIlllinococclls a/blls 7, R. jlavefaciens FD-l, R. a/blls 1Il0Z a, Prevo/ella
rlllllinico/a D31D, Se/enolllonas rlllllinantiulII D, Blltyrivibrio jlbriso/vens, and StreptococCllS
bovis JB 1 were used as pure cultures. Alfalfa and elephant grass were used as substrates. The
extracts were used at 0, 5, 10,20,30 and 50 % ofthe substrates. The samples were incubated at
39°C for 120 h. Gas production, ammonia released and volatile fatty acid were estimated. The
result showed that ethanol, chloroform and non-basic extracts but not the amino acid were toxic
to the mixed rumen microbes. All the three extracts inhibited the growth of all pure cultures
except Se/enolllonas rlIl11inantlllll.
Extracts containing tannin were more inhibitOlY to rumen bacteria suggesting that tannin
was one of the problem compound in A. anglls/issillla. Experiments were subsequently set to
isolate tannin tolerant or degrading bacteria. Tannin was extracted from A. angllstissillla and
Calliandra ca/othyrslls leaves. Four straight rods and three spherical bacteria were isolated
using roll tubes emiclled with tannic acid inoculated with rumen fluid from sheep and goats.
The isolates were characterized by morphology, products of fermentation and restriction
fragment length polymorphism (RFLP). Morphological, fermentative and RFLP
characterization indicate that the cocci isolates were Streptococclls while the rods were closely related to recently isolated tannin tolerant bacteria (ES 14.2) which had been shown to cluster
with Klebsiella