Isolation of fungi from dung of wild herbivores for application in bioethanol production

Abstract

Producing biofuels such as ethanol from non-food plant material has the potential to meet transportation fuel requirements in many African countries without impacting directly on food security. The current shortcomings in biomass processing are inefficient fermentation of plant sugars, such as xylose, especially at high temperatures, lack of fermenting microbes that are able to resist inhibitors associated with pre-treated plant material and lack of effective lignocellulolytic enzymes for complete hydrolysis of plant polysaccharides. Due to the presence of residual partially degraded lignocellulose in the gut, the dung of herbivores can be considered as a natural source of pre-treated lignocellulose. A total of 101 fungi were isolated (36 yeast and 65 mould isolates). Six yeast isolates produced ethanol during growth on xylose while three were able to grow at 42 °C. This is a desirable growth temperature as it is closer to that which is used during the cellulose hydrolysis process. From the yeast isolates, six isolates were able to tolerate 2 g/L acetic acid and one tolerated 2 g/L furfural in the growth media. These inhibitors are normally generated during the pre-treatment step. When grown on pre-treated thatch grass, Aspergillus species were dominant in secretion of endo-glucanase, xylanase and mannanase.

A comparative genomics study of 23 Aspergillus species from section Flavi

“…Carbohydrate-Active enZymes (CAZymes) are essential for what carbon sources a species can degrade and utilize. Within section Flavi the CAZymes/carbon utilization is mainly described for A. oryzae 1,2,40 and to a lesser extent for A. flavus [41][42][43][44][45] and A. sojae 46,47 , while only incidental studies have been performed with other species of this group [48][49][50][51][52][53][54] , often describing production or characterization of a certain CAZyme activity or protein, respectively.…”

“…The A. togoensis clade has a reduced set of xylanolytic and xyloglucanolytic genes, but this is not reflected in the growth. In contrast, GH115 (alpha-glucuronidase) genes are expanded in clades A. flavus, A. tamarii, and A. nomius (xylanolytic enzymes or activity have been reported from several species from these clades [49][50][51]53,[58][59][60][61][62] ), GH62 (arabinoxylan arabinofuranohydrolase) was expanded in clade A. leporis, and clades A. leporis and A. avenaceus were the only clades with CE15 (glucuronoyl esterases), which were also found in Aspergillus species outside section Flavi.…”

Isolation and morphological characterization of endophytic fungi isolated from mangrove plants along the Kenyan coastline

“…The phialides appeared to be flask-shaped and covered the surface of the vesicle. Above the phialides, the conidia formed radial chains (Liu et al, 2007;Makhuvele et al, 2017).…”

The Improvement of Bioethanol Production by Pentose-Fermenting Yeasts Isolated from Herbal Preparations, the Gut of Dung Beetles, and Marula Wine

“…All yeast isolates capable of fermenting D-xylose and L-arabinose were identified using DNA sequencing as described by Makhuvele et al [ 17 ]. The ZR Fungal/Bacterial DNA MiniPrep TM Kit (Zymo Research) was used for genomic DNA extraction, according to the instructions of the manufacturer.…”

“…LC Solution Operation analysis was used to process sample data. Known standards of D-xylose, L-arabinose, L-arabitol, and D-xylitol were used to calculate the concentration unknowns [17].…”