Effect of pretreatment of rubber material on its biodegradability by various rubber degrading bacteria

Abstract

The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six recently isolated and characterized rubber degrading bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas. All strains were able to use natural rubber (NR) as well as NR latex gloves as sole carbon source. Extraction of NR latex gloves by organic solvents resulted in an enhancement of growth for three of the selected strains. On the other hand, growth of Gordonia sp. (strain Kb2 and Kd2), Mycobacterium fortuitum NF4 and Micromonospora aurantiaca W2b on synthetic cis-1,4-polyisoprene did only occur after removal of the antioxidants, that are usually added during manufacture to prevent aging of the materials. Detailed degradation studies performed with Gordonia sp. Kb2 revealed an enhanced mineralization of pretreated NR latex gloves and mineralization of purified natural rubber (NR), indicating the actual mineralization of cis-1,4-polyisoprene rubber constituent even after removal of non-rubber constituent that may act as co-metabolic substrate and support microbial growth. Further analysis by scanning electron microscopy (SEM) clearly demonstrated the enhanced colonization efficiency of these bacteria towards pretreated NR latex gloves. Colonization was additionally visualized by staining of overgrown NR latex gloves with Schiff's reagent, and the purple color produced in the area of degradation was an evidence for the accumulation of aldehydes containing oligomers. Further enhancement of latex gloves degradation could be achieved after successive replacement of mineral salts medium during cultivation. Thereby, a rapid disintegration of untreated NR latex gloves material was accomplished by Gordonia sp. strain VH2.

Natural rubber degradation by laccase and manganese peroxidase enzymes of Penicillium chrysogenum

“…Degradation was also confirmed by SEM studies. Berekaa et al (2000) conducted similar work and tested the biodegrading ability of different bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas. All strains were able to use NR as well as NR latex gloves as sole carbon source.…”

“…In a tightly stopper bottle, 10 ml of fuchsin reagent was added to a sample and kept for incubation for 10-30 min at room temperature. After 10-30 min, excess amount of the reagent was discarded and 10 ml of the sulphite solution was added in order to suppress non-specific reaction of untreated sample (Berekaa et al 2000).…”

Enzymatic studies on Natural rubber biodegradation by Bacillus pumilus

“…There was a change in the organic car-bon content along with the average molecular weight of the treated rubber samples indicated rubber hydrocarbon utilization and its degradation. Berekaa et al, (2000) conducted similar work and tested the biodegrading ability of different bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas sp. All strains were able to use natural rubber (NR) as well as NR latex gloves as sole carbon source.…”

Degradation of non-vulcanized natural rubber renewable resource for fine chemicals used in polymer synthesis

“…Members of the second group show weaker growth in submerged culture but grow and form clear zones on NR latex overlay agar plates. These bacteria belong to Streptomycetes and related genera [46,47] . From the several microorganisms isolated and tested Actinomycetes showed the ability to degrade NR and to use it as carbon source [48] .…”

“…Numerous publications, as for example [21,[25][26][27][28][29][30][31][32][33][34][35][41][42][43][44][45][46][47][48][49][50][51][52][53][54] , are devoted to oxidative methods of degradation natural rubber. The widely used approach is degradation through the epoxidation reaction of isoprene units of the rubber polymer chain.…”