In recent times, immunosuppressants are receiving considerable importance globally for its significant contribution in medical field. Rapamycin (sirolimus) is a potent immunosuppressant which has antifungal, anti-aging, neuroprotective, anti-tumor activities. Rapamycin is produced by many strains of Streptomyces hygroscopicus by submerged fermentation technique. Inadequate amount of the drug synthesized by the species leads to a great challenge to the engineers for further development and industrialization of this important polyketide. Therefore, an in-depth study with respect to bioprocess engineering aspects is required for enhanced production of this important antibiotic. In this review, various bioengineering aspects of industrial production of this metabolite viz., metabolic engineering, optimization, strain improvement strategies and kinetics studies have been discussed.

Hemicellulosic sugars from a Kraft dissolving pulp mill can be valorized through the integration of a biorefinery for furfural production. Furfural is a multipurpose platform chemical, with derivatives that can replace many organic compounds currently produced from fossil resources. A novel process for furfural production from biomass, with a Kraft mill prehydrolysate stream as feedstock is proposed. The process consists of three steps: prehydrolysate concentration using nanofiltration membranes, sugars conversion and product purification. It has a production capacity of 47 t/d. A scale up evaluation of the membrane unit based on experimental data was carried out. A simulation model for the process has been developed and an integration study has been performed. To reduce the energy consumption of the biorefinery, an optimized heat exchanger network and an absorption heat pump for implementation were designed. The energy and material integration of the biorefinery is feasible and the utility demands can be supplied by the receptor mill. A techno-economic evaluation of the developed process showed that it is economically feasible and a return on capital employed (ROCE) as high as 36% can be obtained.

The inorganic carbon assimilation mechanisms of photosynthesis were investigated in male gametophytes, female gametophytes and juvenile sporophytes of Undaria pinnatifida after blue light and red light exposure. pH compensation points of the three types with blue light exposure were 8.93, 8.91 and 9.71 respectively. With red light exposure, pH compensation points were lower at 8.70, 8.67 and 8.77. Blue light might promote the accumulation of intracellular HCO–3 or CO2 and supplement the photosynthetic absorption of inorganic carbon. However, this benefit was weakened by the presence of high concentration inorganic carbon. The affinity of photosynthesis for inorganic carbon with blue light exposure was higher than that with red light. U. pinnatifida might primarily rely on CO2(aq) as carbon source in red light.

Xylitol is a highly valued, naturally occurring pentahydroxy sugar alcohol, present in small amounts in some fibrous fruits and vegetables. Owing to its anti-diabetic properties and various other health benefits, xylitol has found wide applications in food and pharmaceutical industries. Industrially, xylitol is produced by chemical hydrogenation of D-xylose, which requires nickel catalysts, high temperature, and high pressure. As an alternative, biotechnological methods which involve the bioconversion of lignocelluloses, the most abundant, renewable and economical sources of polysaccharides, have gained considerable importance. Lignocellulosic biomass is first hydrolysed to obtain xylose sugars, detoxified to remove the inhibitors produced as a result of hydrolysis, and then fermented using microorganisms to produce xylitol. This paper reviews the recent research and developments on the production of xylitol from different types of lignocellulosic biomass, using various methods of pre-treatments for hydrolysis, detoxification, and fermentation, along with the various beneficial aspects and wide industrial applications of xylitol.

The potential usefulness of common reed as a biomass feedstock has been investigated. Part I of this investigation focuses on results from above ground biomass subjected to hot water extraction (HWE) prior to soda pulping. Results are compared to soda pulping only. Up to 12.8% of biomass feed (oven dry basis) may be removed by HWE. The extract contains up to 19 mmol/L of reducing sugars available for further processing into biofuel or other biochemicals. Common reed soda pulp after HWE provided lower pulp yield with higher lignin and higher pentosans content relative to reed biomass feedstock that was soda pulped only. Differences in process variables may explain some apparent inconsistencies. Soda pulps (both with and without HWE) were subjected to further bleaching and pilot scale papermaking processes. Bleaching results and paper properties are reported in Part II of this investigation.