Cellulolytic bacteria from soils in harsh environments.
It is believed that the exposure of organisms to harsh climate conditions may select for differential enzymatic activities, making the surviving organisms a very promising source for bioprospecting. Soil bacteria play an important role in degradation of organic matter, which is mostly due to their ability to decompose cellulose-based materials. This work focuses on the isolation and identification of cellulolytic bacteria from soil found in two environments with stressful climate conditions (Antarctica and the Brazilian semi-arid caatinga). Cellulolytic bacteria were selected using enrichments at high and low temperatures (4 or 60°C) in liquid media (trypic soy broth-TSB and minimum salt medium-MM) supplemented with cellulose (1%). Many of the isolates (119 out of 254-46.9%) displayed the ability to degrade carboxymethyl-cellulose, indicating the presence of endoglucolytic activity, while only a minority of these isolates (23 out of 254-9.1%) showed exoglucolytic activity (degradation of avicel). The obtained isolates revealed a preferential endoglucolytic activity according to the temperature of enrichments. Also, the identification of some isolates by partial sequencing of the 16S rRNA gene indicated that the Bacteroidetes (e.g., Pedobacter, Chryseobacterium and Flavobacterium) were the main phylum of cellulolytic bacteria isolated from soil in Antarctica; the Firmicutes (e.g., Bacillus) were more commonly isolated from samples from the caatinga; and Actinobacteria were found in both types of soil (e.g., Microbacterium and Arthrobacter). In conclusion, this work reports the isolation of bacteria able to degrade cellulose-based material from soil at very low or very high temperatures, a finding that should be further explored in the search for cellulolytic enzymes to be used in the bioenergy industry.
Laboratory of Molecular Biology and Microbial Ecology, NIB, Center of Biotechnological Researches, University of Mogi das Cruzes, Mogi das Cruzes, SP 08780-970, Brazil.
Fábio Lino
FL
Soares
Itamar Soares
IS
Melo
Armando Cavalcante Franco
AC
Dias
Fernando Dini
FD
Andreote
D000864:Antarctic Regions; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism*; D001938:Brazil; D044602:Cellulases / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D016000:Cluster Analysis; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D003889:Desert Climate; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013696:Temperature
D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D002482:Cellulose; D044602:Cellulases