Lignocellulolytic enzymes and bacteria associated with the digestive tracts of Stenochironomus (Diptera: Chironomidae) larvae

Abstract

ABSTRACT. We analyzed the digestive activity of the enzymes that digest cellulose and hemicellulose and the bacterial community that is capable of hydrolyzing wood compounds in the digestive tracts of Stenochironomus (Diptera: Chironomidae) larvae, which are miners of decomposing submerged tree and bush branches. Based on quantification of reducing sugars, these larvae have a limited capacity for cellulose degradation but a good capacity for xylan hydrolysis. We isolated 31 types of colonies from two larval morphotypes, of which 19 tested positive for the capacity to hydrolyze at least one of the four substrates that were used as the main carbon source in the culture media. Their woody compound degradation capacity was assessed using colorimetric tests. The bacteria were identified by the analysis of the 16S rRNA gene. None of the bacteria were capable of degrading lignin. The genus Pseudomonas had the greatest species richness; Bacillus spp exhibited the greatest capacity for degrading the different substrates, and Sphingobium was found in both morphotypes. Microorganisms participate in the degradation of wood consumed by Stenochironomus larvae. This is the first report of lignocellulolytic bacteria and enzymes in the digestive tracts of mining chironomids.

Cellulose degrading bacteria isolated from industrial samples and the gut of native insects from Northwest of Argentina

“…Samples were inoculated into different media – DNB and DTSB, and mVL70 – within the 12 h of collection to increase bacterial recovery . Enrichment cultures at pH values around neutrality (pH 7.0 ± 1) were incubated aerobically at 30 °C since aerobic and facultative anaerobic microbes also occur in insect guts . As a result, bacterial growth (OD 600 nm > 0.9) was observed in diluted nutritive media amended with SCB, Avicel, and CMC.…”

French invasive Asian tiger mosquito populations harbor reduced bacterial microbiota and genetic diversity compared to Vietnamese autochthonous relatives

“…They display various catabolic abilities including the production of hydrolases involved in the degradation of oligosaccharides, and in termite hosts they may participate in the degradation of plant compounds (Aylward et al, 2013 ). Moreover, these bacteria have already been identified in other plant-feeding insects including mosquitoes Anopheles maculipenis, Anopheles gambiae, Anopheles stephensis , and Aedes aegypti (Dong et al, 2009 ; Ramírez-Puebla et al, 2010 ; Dinparast Djadid et al, 2011 ; Gayatri Priya et al, 2012 ; Terenius et al, 2012 ; Koroiva et al, 2013 ). From these observations, it could be assumed that Sphingomonadaceae are important in making plant sugar available to the mosquito host, by degrading oligosaccharides in the mosquito gut or acquiring them from the environment.…”

Cellulose: from biocompatible to bioactive material

“…This ecosystem consists of bacteria or protozoa depending on the species which produce enzymes dedicated to break down cellulose. [54][55][56][57] The main glycolytic enzymes involved in the biological conversion of cellulose to glucose are endoglucanases, cellobiohydrolases and b-glucosidases. While endoglucanases randomly hydrolyze 1,4-b bonds along the cellulose chains, cellobiohydrolases split off cellobiosyl units from non-reducing end groups and b-glucosidases cleave glucosyl units from nonreducing end groups.…”

“…54 There are also other enzymes which are dedicated to hydrolyze the other compounds from plant cell walls such as hemicellulase and xylan 1,4-b-xylosidase. 55,57 Some fungi are also able to break down cellulose. Actually, fungi are among the most degradative organisms inducing biodeterioration of paper-based items.…”