Use of Silage Bacteria as Enterosorbents to Reduce Aflatoxin Contamination

Abstract Text:

The aim was to determine the effects of bacteria strain, viability and pH on the aflatoxin B₁ (AFB₁)- binding capacity of silage bacteria. In Experiment 1, each of 10 silage bacteria strains (Table 1) was screened for their AFB₁-binding capacity by growing them on de Man-Rogosa-Sharpe broth to a population of 10⁹ cfu/ml in quadruplicate. The suspension was centrifuged at 2500 x g for 10 min and the pellet was suspended in a 1.5-ml solution (5 µg/ml) of AFB₁ in phosphate buffered saline (PBS) for 24 h at 20^oC. Bacterial (bacteria suspended in PBS) and AFB₁ Controls were also incubated. Supernatant samples after centrifuging were used to quantify the presence of unbound aflatoxin by High-Pressure Liquid Chromatography. Data were analyzed as a completely randomized design. Each bacterium bound more than 18% of AFB₁, and the greatest responses occurred with L. plantarum R2014 (32.95%), L. buchneri R1102 (30.30%) and P. acidilactici EQ01 (25.38%). In Experiment 2, the latter 3 strains were tested to determine how pH and bacterial viability influence their ability to bind AFB₁. Bacterial cells (10⁹ cfu/ml) were incubated in either 4 ml of PBS (viable cells) or 2M HCL (dead cells) and centrifuged as described above. Pellets were incubated in quadruplicate in AFB₁ solution as above at pH 6, 2.5 and 8 to simulate the pH in the rumen, abomasum and intestine of dairy cows, and AFB₁ binding was quantified. Data were analyzed as a completely randomized design with a 3 x 2 x 3 factorial treatment arrangement. Dead cells of L. plantarum R2014 (32.62% vs. 24.78%) and L. buchneri R1102 (45.05% vs. 17.77%) bound more AFB₁ than viable cells, whereas a contrasting response was detected for P. acidilactici EQ01 (2.44% vs. 21.92%, respectively). The pH of 2.5 increased AFB₁ binding compared with pH 6 and 8 (P<0.05). All bacterial strains showed AFB₁-binding ability but the efficacy was dependent on the bacteria strain, viability and pH. More work is required to test the ability of the bacteria to bind AFB₁in animal feeds.

Table 1.  Bacterial strains tested for AFB₁binding capacity

Bacteria	Strain
Lactobacillus plantarum	R2014
	EQ12
	PT5B
Lactobacillus buchneri	R1102
Pediococcus acidilactici	R2142
	EQ01
Pediococcus pentosaceus	EQ44
	IA38
Propionibacterium jensenii	SE253
Propionibacterium acidipropionici	EQ42

Keywords: aflatoxin, silage bacteria, enterosorbents