Efficient production of second generation ethanol and xylitol by yeasts from Amazonian beetles (Coleoptera) and their galleries

Abstract

Beetles of the Passalidae family live and feed on decaying wood and their guts are richly colonized by yeasts. The goal of this research was to prospect xylolytic yeasts with potential for the production of second-generation bioethanol. Therefore, 83 specimens of beetles belonging to the Passalidae and the Scarabaeidae families were collected in the Amazonian rainforest in Itacoatiara -AM, Brazil. Morphological differences of the beetles were identified and 25 chosen specimens were dissected. Yeasts from galleries inhabited by beetles and from insect guts were isolated. Isolates were previously selected through tolerance tests for temperature, ethanol and xylose assimilation capacity. Those isolates were then submitted to a panel of conditions related to ethanol production. The ethanol production reached 24.70 g.L -1 and the xylitol production reached 21.66 g.L -1. One of the isolates with a promising profile was identified as Spathaspora roraimanensis and six as Spathaspora passalidarum. Three isolates showed to be more promising and, curiously, all came from the gut of the species Popilius marginatus (Percheron, 1835). In plate testing, however, the isolates obtained from galleries showed a greater capacity to assimilate xylose. As reported in this field of study, no isolate tolerated all conditions tested. Wild isolates with this profile may be used for testing larger-scale ethanol production, genetic engineering, or evolutionary techniques.

Spathaspora brunopereirae sp. nov. and Spathaspora domphillipsii sp. nov., two d-xylose-fermenting ascosporogenous yeasts from Amazonian Forest biomes

“…Between 2019 and 2021, approximately 4253–10343 km 2 of Brazilian Amazonian forest have been affected by fire, leading to a severe reduction in biodiversity [13]. Yeast biodiversity from Brazilian Amazonian biomes is only beginning to be explored, and most of the work done in the region was focused on the search of new non-conventional yeasts for bioethanol production [3, 7, 14]. In these studies four new Spathaspora species were described, Sp.…”

“…Sp. passalidarum was later isolated from rotting wood and passalid beetles in Amazonian forest sites in Brazil [2, 3], and from rotten wood obtained from Boatianman Nature Reserve in Central China [4]. Sp.…”

Yeasts from tropical forests: Biodiversity, ecological interactions, and as sources of bioinnovation

“…This yeast was also isolated from rotting wood in the Boatianman Nature Reserve in Central China, characterized by a typical warm‐temperate natural landscape and typical climate features of the transition zone (Ren et al, 2014). However, most isolates of this species were obtained in the Brazilian Amazonian rainforest biome (Cadete et al, 2012; Souza et al 2017). This species occurs in the Amazonian rainforest in rotting wood or passalid beetles associated with this substrate.…”

Exploring Natural Fermented Foods as a Source for New Efficient Thermotolerant Yeasts for the Production of Second-Generation Bioethanol

“…It has been said that one of the reasons for the low levels of ethanol from this sugar is that elevated temperatures and low oxygen availability considerably reduce the rate of conversion of xylose to ethanol, as they decrease the concentrations of ATP required for the functioning of xylose transporters in xylose-fermenting yeasts [28]. Yeasts that ferment xylose have been isolated from different habitats such as decaying wood, tree exudates, wood-boring insects, soil, rotten fruits, and flowers [29][30][31][32]. However, to the best of our knowledge, this is the first report describing the isolation of potential xylose fermenting yeasts from natural sourdoughs.…”