Application of microbial extracellular carbohydrate polymeric substances in food and allied industries.

Extracellular polymeric substances (EPS) are biopolymers, composed of polysaccharides, nucleic acids, proteins and lipids, which possess unique functional properties. Despite significant strides made in chemical production processes for polymers, the niche occupied by exopolysaccharides produced by bacteria, yeast or algae is steadily growing in its importance. With the availability of modern tools, a lot of information has been generated on the physico-chemical and biological properties using spectrometric tools, while advanced microscopic techniques have provided valuable insights into the structural-functional aspects. The size of EPS generally ranges between 10 and 10,000 kDa. The wide spectra of applications of EPS as adhesives, stabilizer, gelling, suspending, thickening agent, and surfactants in food and pharmaceutical industries are observed. The health benefits of these EPS enable the improvement of dual function, added value, and green products. This review summarizes previous work on the structural composition, rheological and thermal behaviour, and biosynthetic pathways of EPS and bioprocesses developed for their production. This review also considers each of the above factors and presents the current knowledge on the importance and refinement of available downstream protocols and genetic engineering towards specific food applications, which can help to diversify their prospects in different food and allied industries.

Statistical optimization of process parameters for improvement of phycobiliproteins (PBPs) yield using ultrasound-assisted extraction and its kinetic study.

The present study is mainly concerned for the development of an optimal ultrasound-assisted extraction (UAE) condition for phycobiliproteins (PBPs) from Oscillatoria sp. (BTA 170) using Taguchi methodology. Four process parameters viz. solid to liquid ratio, duty cycle, electrical acoustic intensity, and pH, for UAE were optimized using Taguchi methodology for enhanced PBPs extraction. The ratio of signal to noise (S/N) was used to compute the optimized condition required to attain a higher yield of PBPs, the average performance of individual parameter and corresponding interactive effects. The statistically significant parameters with their contribution were assessed using Analysis of variance (ANOVA). Results showed that duty cycle contributed the maximum influence (30.81%) on phycocyanin (PC) extraction followed by a solid liquid ratio (28.62%), pH (22.46%) and electrical acoustic intensity (18.10%). The highest contribution on the extraction of phycoerythrin (PE) was found from pH (33.16%), followed by duty cycle (31.57%), solid to liquid ratio (22.83%) and electrical acoustic intensity (12.45%). For extraction of allophycocyanin (APC), the duty cycle, solid to liquid ratio, pH and electrical acoustic intensity contributed 29.47, 29.07, 29.03, and 12.43% respectively. Results obtained from Taguchi methodology indicated that enhanced PC (94.10%), PE (95.20%) and APC (90.54%) can be achieved with solid-liquid ratio (0.2 g/ml), electrical acoustic intensity (16.99 w/cm2), duty cycle (75%), and pH 7 than the yield of PBPs obtained under unoptimized condition. In the present study, higher yield of PC (38.99%), PE (20.84%), and APC (11.93%) were attained with UAE compared to yield obtained from homogenized Oscillatoria sp. BTA 170 using 0.05 M phosphate buffer. Batch extraction data of PBPs under UAE was fitted well with the second order model. The values of second-order rate constant (k) were computed as 6.66 × 10-4, 64.09 × 10-4 and 1.49 × 10-4 L/mg/min for extraction of PC, PE and APC respectively. The PBPs exhibited significant antioxidant property and hydrogen peroxide scavenging activity, which were increased with the enhancement of PBPs concentration.

Advances in exopolysaccharides based bioremediation of heavy metals in soil and water: A critical review.

Extracellular polysaccharides or Exopolysaccharides (EPS) are extensively studied bacterial byproducts with high molecular weight attributed to several applications. In spite of their application in the field of food, pharmaceutical, nutraceutical, herbicidal and cosmeceutical industries they were well known for their efficiency in the bioremediation of water and soil tainted with heavy metals. These heavy metals are comparatively high in density than water and are involved in several biological processes. But slight increase in levels can create toxicological bias. The techniques like electrodialysis, chemical precipitation, ion exchange and membrane separation have a lot of disadvantages akin to high energy consumption, high cost, partial exclusion, and creation of poisonous mire. In this context, EPS has a top role to play in the bioremediation of heavy metals. This review gives the critical assessment of the extensive work done to deal this issue by different groups in the last five years. It also explains how different natural circumstances have attributed to the advancement of EPS production, thereby increasing the capacity of bioremediation to deal the issue of heavy metal contamination in both soil and water. A detailed discussion of the EPS formation by bacteria and fungi with their applicability was reported.