Isolation and identification of termite gut symbiotic bacteria with lignocellulose-degrading potential, and their effects on the nutritive value for ruminants of some by-products

Abstract

The termite gut contains different kinds of lignin and lignocellulose degrading microbes. This study was conducted to isolate and identify termite gut symbiotic bacteria with lignocellulose-degrading potential, and evaluate their effects on the chemical composition and in vitro digestibility of wheat straw and date leaves. Termite gut contents were extracted and cultured in 9 different culture media containing lignin and lignocellulosic materials that had been prepared from water-extracted sawdust and wheat straw. Three superior bacteria capable of growing on all media, and with higher lignin peroxidase activity, were selected and subjected to molecular identification.Following this, wheat straw and date leaves were incubated with the isolated bacteria in liquid medium for 6 weeks. 16S rRNA sequence analysis showed that these isolates possessed 97, 99 and 97% similarity with Bacillus licheniformis, Ochrobactrum intermedium and Microbacterium paludicola, respectively. The highest (P<0.05) dry matter (DM) loss in wheat straw and date leaves was observed following treatment with B. licheniformis. In the case of wheat straw, the organic matter (OM) and neutral detergent fibre (NDF), and for date leaves OM, NDF and acid detergent lignin (ADL) contents were not influenced by the treatments (P>0.05). The greatest and lowest (P<0.05) ADF content of wheat straw was observed as a result of treatment with B. licheniformis and O. intermedium, respectively. However, bacterial treatments decreased (P<0.05) ADF content of date leaves when compared to the control. Acid detergent lignin content of wheat straw was decreased (P<0.05) by bacterial treatments in comparisons to the control. For wheat straw, the highest and lowest (P<0.05) value of crude protein (CP) was observed in the case of M. paludicola and O. intermedium treatments, respectively. For date leaves, the CP content of the control treatment was 3 highest (P<0.05) among treatments. For wheat straw, bacterial treatments enhanced (P<0.05) DM, OM and ADF digestibility when compared to the control. However, highest and lowest (P<0.05) CP digestibility was observed using O. intermedium and M. paludicola, respectively. For date leaves, treatment with B. licheniformis significantly increased (P<0.05) digestibility of DM, OM and NDF when compared to the others.However, CP and ADF digestibility was not different (P>0.05) between experimental groups. Overall, the results of this study showed that the isolated bacteria partially changed the chemical composition of wheat straw and date leaves while, they improved digestibility of nutrients. These bacteria are suitable candidates for increasing nutritive value of by-products for ruminants.

Isolation and identification of cellulolytic bacteria from gastrointestinal tract of Arabian horse and investigation of their effect on the nutritional value of wheat straw

“…Many species of fungi which are effective lignin degraders have been used to assess their ability to improve the nutritive value of fodder for ruminant nutrition (Yamakawa et al 1992;Howard et al 2003). Consistent with our results, Azizi-Shotorkhoft et al (2016) reported that processing WS using bacterial isolates from the termite gut over 6 weeks resulted in a higher disappeared DM compared to treatment without bacterial inoculation. Borji (2003) observed an increase in disappeared DM when processing WS by three bacterial isolates from the termite gut as well as its compatibility with our results.…”

“…Similar to the study by Azizi‐Shotorkhoft et al . (), the CP content of WS increased when treated with Ochrobactrum intermedium, in our study, the CP content of WS increased when treated with bacterial isolates. Kerr and Kerr () reported a significant increase in CP content of peanut hulls treated with Arthrobacter for 10 days.…”

“…Consistent with our results, Azizi‐Shotorkhoft et al . () reported that processing WS using bacterial isolates from the termite gut over 6 weeks resulted in a higher disappeared DM compared to treatment without bacterial inoculation. Borji () observed an increase in disappeared DM when processing WS by three bacterial isolates from the termite gut as well as its compatibility with our results.…”

“…Azizi-Shotorkhoft et al (2016) reported that bacterial treatments enhanced DM and OM digestibility of WS compared to control treatment. In the experiments of these researchers, the highest and lowest CP digestibilities were observed for WS treated with isolates O. intermedium and Microbacterium paludicola respectively.…”

Rumen fermentation of lignocellulosic biomass from wheat straw and date leaf inoculated with bacteria isolated from termite gut

“…Information on the use of these processed by-products in ruminants is scarce, with few data available on the effects of processing on nutritive value, rumen fermentation, and overall animal. In our previous work, incubation of lignocellulosic biomass from wheat straw (LBWS) and date (Phoenix dactylifera) leaf (LBDL) for 6 weeks with lignocellulose-degrading bacteria isolated from termite gut partially changed their chemical composition, while increased nutrients digestibility (Azizi-Shotorkhoft et al, 2016). We hypothesized that decreasing the processing period from 6 to 3 weeks may have a similar outcome on nutrients digestibility, thus resulting in a more feasible process of ruminant nutrition.…”