Cyanogenesis in Bovine Rumen Fluid and Pure Cultures of Rumen Bacteria

Majak, W.; Cheng, K.-J.

doi:10.2527/jas1984.593784x

Cited by 27 publications

(33 citation statements)

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“…These differences cannot be attributed to solubilized forage enzymes because substrate incubations clearly indicated the absence of p-glucosidase activity in fresh orchardgrass and alfalfa, in agreement with previous tests on these forages (Majak and Cheng 1984). It appears that rumen microorganisms can distinguish the two monosaccharides on the basis of their aglycone moieties.…”

supporting

confidence: 91%

“…In a previous study, rates were determined for the in vivo disappearance of HCN from the rumen and we indicated that its rate of absorption from the rumen could follow first order kinetics (Majak and Cheng 1984 Recently, the rates of hydrolysis for three cyanogenic glycosides were determined with a B-glucosidase preparation from the hamster caecum (Frakes et al 1986 …”

mentioning

confidence: 99%

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Hydrolysis of the Cyanogenic Glycosides Amygdalin, Prunasin and Linamarin by Ruminal Microorganisms

Majak¹,

Cheng²

1987

Can. J. Anim. Sci.

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confidence: 91%

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confidence: 99%

Hydrolysis of the Cyanogenic Glycosides Amygdalin, Prunasin and Linamarin by Ruminal Microorganisms

Majak¹,

Cheng²

1987

Can. J. Anim. Sci.

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“…The high cyanogenic activity of mixed populations of ruminal bacteria (19,20) suggests that this is not an isolated case and that other enzymes with activity towards these cyanogenic compounds are present in the rumen. Preliminary qualitative studies indicate that CdxA is also capable of releasing free cyanide from both prunasin and amygdalin (data not shown).…”

mentioning

confidence: 98%

“…In the 1980s Majak and Cheng (19,20) demonstrated that many ruminal bacteria, including P. ruminicola, have the ability to release free cyanide from the glycosides amygdalin (laetrile), prunasin, and linamarin. ␤-Glucosidases play a key role in the initial step of hydrolyzing these compounds into glucose units and the cyanogenic aglycone (8,22).…”

mentioning

confidence: 99%

Cloning, sequencing, and characterization of a membrane-associated Prevotella ruminicola B(1)4 beta-glucosidase with cellodextrinase and cyanoglycosidase activities

Wulff-Strobel

Wilson

1995

J Bacteriol

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Prevotella ruminicola B 1 4 is a gram-negative, anaerobic gastrointestinal bacterium. A 2.4-kbp chromosomal fragment from P. ruminicola encoding an 87-kDa aryl-glucosidase (CdxA) with cellodextrinase activity was cloned into Escherichia coli DH5␣ and sequenced. CdxA activity was found predominantly in the membrane fraction of both P. ruminicola and E. coli, but P. ruminicola localized the protein extracellularly while E. coli did not. The hydrolase had the highest activity on cellodextrins (3.43 to 4.13 mol of glucose released min ؊1 mg of protein ؊1) and p-nitrophenyl-␤-D-glucoside (3.54 mol min ؊1 mg of protein ؊1). Significant activity (70% of p-nitrophenyl-␤-D-glucoside activity) was also detected on arbutin and prunasin. Less activity was obtained with cellobiose, amygdalin, or gentiobiose. CdxA attacks cellodextrins from the nonreducing end, releasing glucose units, and appears to be an exo-1,4-␤-glucosidase (EC 3.2.1.74) which also is able to attack ␤-1,6 linkages. Comparison of the deduced amino acid sequence with other glycosyl-hydrolases suggests that this enzyme belongs to family 3 (B. Henrissat, Biochem. J. 280:309-316, 1991). On the basis of this sequence alignment, the catalytic residues are believed to be Asp-275 and Glu-265. This is the first report of a cloned ruminal bacterial enzyme which can cleave cyanogenic plant compounds and which may therefore contribute to cyanide toxicity in ruminants.Ruminant animals such as cattle and sheep have evolved to utilize the extensive fermentative abilities of their reticuloruminal microflora. This symbiotic relationship gives the ruminant animal access to a variety of herbaceous foodstuffs such as cellulose and hemicellulose which are nutritionally unavailable to monogastric animals. In addition to cellobiose, cellodextrins are a major product of cellulose hydrolysis in the rumen. Ruminal bacteria that can utilize cellodextrins are common. Prevotella ruminicola B 1 4 possesses extracellular cellodextrinase activity (27) and can utilize water-soluble cellodextrins (up to seven glucose units in length) as carbon and energy sources. In this paper, we report the cloning, sequencing, and partial characterization of an 87-kDa membrane-associated exo-␤-glucosidase.Although normally beneficial, the expanded digestive repertoire of the ruminant animal can also be a detriment. A significant number of range forages such as serviceberry (Amelanchier alnifolia), bird's foot trefoil (Lotus corniculatus), chokeberry (Prunus virginiana), various sorghum species, white clover (Trifolium repens), and arrowgrass (Triglochin spp.) contain cyanogenic glycosides which are hydrolyzed during ruminal fermentation. These glycosides constitute a prominent class of toxic plant compounds (7, 9, 31) which presumably are synthesized to discourage grazing. For a review of the plant biosynthetic routes that produce these glycosides, see the work of Vennesland et al. (31).The P. ruminicola B 1 4 ␤-glucosidase catalyzes the first step in cyanide release from cyanogenic plant glycosides. Sin...

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“…This deciduous shrub is utilized by both domestic and wild ruminants but large intakes can be fatal owing to the natural occurrence of the cyanogenic glycoside, prunasin (Quinton 1985;Majak et al 1980b). The glycoside is rapidly hydrolyzed by microbial enzymes of the rumen (Majak and Cheng 1984) with the resultant release of hydrogen cyanide (HCN) which can be lethal at 2 mg kg-t body weight (Coop and Blakley 1950 (Majak et al 1981).…”

mentioning

confidence: 99%

THE CYANIDE POTENTIAL IN TWO VARIETIES OF Amelanchier alnifolia

Brooke¹,

McDiarmid²,

Majak³

1988

Can. J. Plant Sci.

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The cyanide potential of Saskatoon foliage was re-examined to further elucidate its toxicity to ruminants. Average prunasin concentrations in newly initiated leaves of Amelanchier alnfolia var. cusickii were threefold greater than in A. alnifulia vat . alnifolia. This was determined with an extraction procedure that simplified sample preparation for cyanide determination. lmproved conditions are also described for determining cyanide colorimetrically and for detecting prunasin by liquid chromatography.

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Cyanogenesis in Bovine Rumen Fluid and Pure Cultures of Rumen Bacteria

Cited by 27 publications

References 0 publications

Hydrolysis of the Cyanogenic Glycosides Amygdalin, Prunasin and Linamarin by Ruminal Microorganisms

Hydrolysis of the Cyanogenic Glycosides Amygdalin, Prunasin and Linamarin by Ruminal Microorganisms

Cloning, sequencing, and characterization of a membrane-associated Prevotella ruminicola B(1)4 beta-glucosidase with cellodextrinase and cyanoglycosidase activities

THE CYANIDE POTENTIAL IN TWO VARIETIES OF Amelanchier alnifolia

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