RESUMEN
Biosurfactants, amphiphilic compounds that reduce interfacial tension in oil-aqueous mixtures, are used in the petroleum, pharmaceutical, food, and agriculture industries. Fermentative production of biosurfactants requires expensive sugar or lipid substrates. Lignocellulosic biomass is a relatively cheap and abundant agricultural residue that can be used as an alternative substrate. Currently, several million tonnes of rice and wheat straw are generated globally as agricultural residues, most of which is disposed by open-field burning thereby leading to severe environmental pollution. This study aimed to produce biosurfactants in xylose-rich hydrolysates generated from rice straw. The hydrolysate is also a byproduct of 2G biofuel processes that often goes underutilized. A soil bacterium capable of growing and producing biosurfactants in rice straw hydrolysates, which typically contain growth-inhibitory compounds such as furfural and hydroxymethyl furfural, was isolated. Interestingly, the organism, identified as Serratia nematodiphila, exhibited higher glycolipid formation (4.5 ± 0.6 gL-1) in xylose-rich hydrolysate than in glucose-rich enzymatic hydrolysate (3.1 ± 0.2 gL-1) despite the higher bacterial cell density observed with the latter. The biosurfactants were thermostable and possessed promising emulsifying property and anti-microbial activity against bacteria and yeast. Further optimization of C:N resulted in a 2.8-fold increase in glycolipid production from xylose-rich hydrolysates. This study demonstrates the production of glycolipid biosurfactants from lignocellulosic biomass, a low-cost substrate and offers a plausible strategy for the management of these residues. Further, it also provides insights into the generation of additional high-value compounds in a bioethanol biorefinery to improve its commercial feasibility.
Asunto(s)
Oryza , Fermentación , Hidrólisis , Serratia , Suelo , XilosaRESUMEN
Gut microbiome plays an important role in determining the effectiveness of cancer therapy. The composition of the microbiome is crucial to maintain good digestive health in the host, and to prevent and treat colorectal cancers. Most cancer therapies employ oxidative stress, which disturbs the redox status of the cell, and consequently affect growth, reductive biosynthesis and cell death. Therefore, oxidative stress can undesirably affect the gut microbiome. Hence, it is important to understand the impact of oxidative stress on gut bacteria to devise effective treatment strategies. The current study induces oxidative stress in the model gut bacterium Enterococcus durans (MTCC 3031) with menadione and H2O2. Oxidative stress considerably decreased the redox ratio (NADPH/NADP), an indicator of the redox status, by 55% (menadione) and 28% (H2O2). In addition, an oxidative stress induced decrease in redox ratio decreased folate synthesis by the bacteria, which is an undesirable consequence for the host, since folate deficiency can induce colorectal cancer. Further, oxidative stress considerably decreased growth and the biomass density by 61% (menadione) and 21% (H2O2). Thus, maintenance of the cellular redox status and management of oxidative stress in the gut microbiome may be crucial to the effectiveness of cancer treatment strategies.
Asunto(s)
Enterococcus/efectos de los fármacos , Deficiencia de Ácido Fólico/prevención & control , Ácido Fólico/biosíntesis , Microbioma Gastrointestinal/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Antineoplásicos/efectos adversos , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/etiología , Neoplasias Colorrectales/prevención & control , Enterococcus/metabolismo , Ácido Fólico/análisis , Deficiencia de Ácido Fólico/inducido químicamente , Deficiencia de Ácido Fólico/complicaciones , Deficiencia de Ácido Fólico/microbiología , Microbioma Gastrointestinal/fisiología , Humanos , Peróxido de Hidrógeno/farmacología , Oxidación-Reducción/efectos de los fármacos , Resultado del Tratamiento , Vitamina K 3/farmacologíaRESUMEN
Photon up-conversion, a process whereby lower energy radiations are converted to higher energy levels via the use of appropriate phosphor systems, was employed as a novel strategy for improving microalgal growth and lipid productivity. Photon up-conversion enables the utilization of regions of the solar spectrum, beyond the typical photosynthetically active radiation, that are usually wasted or are damaging to the algae. The effects of up-conversion of red light by two distinct sets of up-conversion phosphors were studied in the model microalgae Chlorella vulgaris. Up-conversion by set 1 phosphors led to a 2.85 fold increase in biomass concentration and a 3.2 fold increase in specific growth rate of the microalgae. While up-conversion by set 2 phosphors resulted in a 30% increase in biomass and 12% increase in specific intracellular neutral lipid, while the specific growth rates were comparable to that of the control. Furthermore, up-conversion resulted in higher levels of specific intracellular reactive oxygen species in C. vulgaris. Up-conversion of red light (654 nm) was shown to improve biomass yields in C. vulgaris. In principle, up-conversion can be used to increase the utilization range of the electromagnetic spectrum for improved cultivation of photosynthetic systems such as plants, algae, and microalgae.