Titolo della Ricerca
"Aflatossine: Impatto nel settore zootecnico ed agro-alimentare"

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Responsabile del progetto Dr. Giuseppe Maglione - gm@iabbam.na.cnr.it

Italian version

Title
"Aflatoxins removal ability of lactic acid bacteria strains isolated from dry fermented
meat products".


INTRODUCTION

The aflatoxins are very toxic worldwide contaminants, particularly to the liver. They are secondary metabolites produced by Aspergillus flavus (Fig. 1) and parasiticus.

Figure 1. Colture of Aspergillus Flavus (from Occupational Safety and Health Administration [OSHA])

 

Their toxicity and carcinogenic effects are well known but the mechanisms have not been elucidated yet. Four aflatoxins commonly occur in pre- and post-harvest contamination of food and feed and these are: AFB1, AFB2, AFG1 and AFG2. The ingestion of aflatoxin B1-contaminated animal feed, by dairy cattle, can result in the presence of aflatoxin M1 (Figure 2), a metabolite of aflatoxin B1, in milk. This metabolite has been found associated to the casein in cheese where it achieves a concentration 5 fold greater than in milk. This is an issue of considerable importance to public health, given the frequent consumption of milk and dairy products by infants.

Figure 2   Structures of Aflatoxins B1, M1, B2, G1 and G2


Aflatoxin B1                                     Aflatoxin M1         


Aflatoxin B2                                 Aflatoxin G1


Aflatoxin G2

Many strategies are under investigation to eliminate or inactivate the aflatoxin contaminants from animal feed and human food chain. Aflatoxin may be degraded by physical (heat, ionizing radiation), chemical (oxidizing, hydrolytic agents) or biological methods. Many investigators are taking into account the role that many organisms, including lactic bacteria, play in removing these compounds.

RESULTS

One hundred microbial clones from naturally occurring microflora of some traditional meat products were isolated on MRS plates. The meat product samples had been manufactured in different areas in Campania region, Italy. Three of them, named LS strain because their high bichemical correlation with Lactobacillus sakei, were selected for this study. We observed that the amount of toxins, in the media, were significantly reduced in presence of these bacteria after 12 hours of incubation at 30° C.(Table 1)

Table 1  Removal of Aflatoxins by the LS strains from artificially (5 µg/ml) contaminated media after 12 hours of incubation at 30 °C.

Bacterial strain

 

% Recovery Aflatoxin

 

 

AfG1

AfB1

AfG2

AfB2

LS1

50

80

40

67

LS2

87

87

65

75

LS3

57

57

45

47

We also noted the changing of the growth parameters by adding 5 mg/ml of aflatoxins solution in MRS media (Fig. 3).

                                                     A                                                                             B
  
Figure 3. Growth curve of LS strains without aflatoxins (A) and in presence of 5µg/ml of toxins added (B).

CONCLUSIONS

Our preliminary data, strongly support the concept that in the broad panel of strategies, detoxification by using bacteria can be considered a useful and more appropriate method to remove or inactivate these contaminants from food.