Fig 1.
Schematic of enrichment experiment strategy.
Eight microbial consortia enriched for microorganisms able to utilize lignin (i.e., base-extracted or Kraft) as carbon source. Four of the consortia had back yard soil and other four had MG soil as the as the original source of microorganisms. The enrichment experiments were conducted in aerobic conditions at 30°C and 37°C. Every two weeks, an aliquot of the growth medium containing microorganisms was transferred to fresh culture medium. The consortia were enriched over six cycles (passages), totaling 12-weeks. Samples were taken for each passage, DNA was extracted and the ribosomal gene 16S rDNA was amplified and sequenced.
Table 1.
Diversity indexes for the original substrate (i.e., MG and BY compost soils) and at the sixth passage of enriched bacterial consortia, for base-extracted and Kraft lignin utilization cultivated at 30°C and 37°C.
Fig 2.
Family level taxonomic profile of bacteria at present in consortia obtained from MG soil over successive passages in enrichment experiment.
M9 medium containing either base-extracted lignin, BE Lig, (panels A and B) or Kraft lignin (panels C and D) was initially inoculated with MG soil (MG) as the source of microorganisms. Experiments were performed at two temperatures. 30°C (panels A and C) and 37°C (panels B and D). Every 2 weeks an aliquot was transferred to fresh growth medium for enrichment in successive passages (0, 1, 2, 3, 4, 5 and 6). Bacterial families are depicted by different colors. For the families classified as Other and Unknown, we were unable to obtain the taxonomic affiliation at the family level, so the closest previous hierarchical level is provided.
Fig 3.
Family level taxonomic profile of bacteria at present in consortia obtained from backyard (BY) soil over successive passages in enrichment experiment.
M9 medium containing either base-extracted lignin, BE Lig, (panels A and B) or Kraft lignin (panels C and D) was initially inoculated with backyard (BY) as the source of microorganisms. Experiments were performed at two temperatures. 30°C (panels A and C) and 37°C (panels B and D). Every 2 weeks an aliquot was transferred to fresh growth medium for enrichment in successive passages (0, 1, 2, 3, 4, 5 and 6). Bacterial families are depicted by different colors. For the families classified as Other and Unknown, we were unable to obtain the taxonomic affiliation at the family level, so the closest previous hierarchical level is provided.
Fig 4.
Venn diagram of bacterial genera present at the 6th passage of enrichment in consortia obtained using either base-extracted (BE-Lig) or Kraft lignin (Kraft) as carbon source at cultivation temperatures of 30°C and 37°C.
Shown in parenthesis is the number of genera for each growth condition with relative abundance above 1%. (A) Bacterial consortia derived from MG compost. (B) Bacterial consortia derived from backyard (BY) compost.
Fig 5.
Bray-Curtis analysis of dissimilarity in the non-metric multidimensional scaling matrix (NMDS) to consortia composition at genus level in relation to the variables type of lignin used as carbon source and temperature.
MG- and backyard (BY) compost derived consortia were analyzed. P0 refers to the original compost; “P1” to “P6” refer to the six passages (selection cycles); The stress number is given at the top. * Stress <0.05 excellent, <0.1 great, <0.2 good and<0.3 bad.