Résumé
To characterize microbial communities present in natural rubber coagula from Hevea brasiliensis latex during maturation and identify microbial taxa (bacteria and fungi) having an impact on dry natural rubber properties.
Microbial community dynamics in natural rubber coagula maturated under controlled conditions were compared and related with the evolution of dry natural rubber properties. The pyrosequencing of 16S (119,837 effective reads) and 18S (131,879 effective reads) rRNA gene regions was performed on 21 samples covering different maturation times and two aeration conditions. Results showed a relatively high bacterial richness (Chao1 estimates of 200-1000) associated with significant bacterial dynamics. Lactic acid bacteria were dominant in the first days of maturation. Then, in aerobic conditions, development of Actinobacteria represented by the family Microbacteriaceae was associated to alkalinization of the samples and a higher sensitivity of natural rubber to thermo-oxidation as evaluated by its plasticity retention index (PRI). In anaerobiosis, the reduced development of bacteria, mostly lactic acid bacteria present, was associated with improved natural rubber properties (higher initial plasticity P
and PRI).
The involvement of microorganisms in the evolution of dry natural rubber properties during the maturation of natural rubber coagula was confirmed. The importance of the structure and dynamics of microbial communities is specifically highlighted.
Natural rubber is a key elastomer for the tire industry and for a variety of other applications. The majority of raw natural rubber is obtained by natural coagulation of Hevea brasiliensis latex under the activity of microorganisms. An improved understanding of the microbial communities involved in the maturation of natural rubber coagula may lead to an improvement in the production process of raw natural rubber to provide a better consistency in natural rubber quality. This article is protected by copyright. All rights reserved.