Gut microbiota has evolved along with their hosts and is an integral part of the human body. Microbiota acquired at birth develops in parallel as the host develops and maintains its temporal stability and diversity through adulthood until death. Recent developments in genome sequencing technologies, bioinformatics and culturomics have enabled researchers to explore the microbiota and in particular their functions at more detailed level than before. The accumulated evidences suggest that though a part of the microbiota is conserved, the dynamic members vary along the gastrointestinal tract, from infants to elderly, primitive tribes to modern societies and in different health conditions. Though the gut microbiota is dynamic, it performs some basic functions in the immunological, metabolic, structural and neurological landscapes of the human body. Gut microbiota also exerts significant influence on both physical and mental health of an individual. An in-depth understanding of the functioning of gut microbiota has led to some very exciting developments in therapeutics, such as prebiotics, probiotics, drugs and faecal transplantation leading to improved health.

An insight into gut microbiota and its functionalities.

Stress, a ubiquitous part of daily human life, has varied biological effects which are increasingly recognized as including modulation of commensal microorganisms residing in the gastrointestinal tract, the gut microbiota In turn, the gut microbiota influences the host stress response and associated sequelae, thereby implicating the gut microbiota as an important mediator of host health This narrative review aims to summarize evidence concerning the impact of psychological, environmental, and physical stressors on gut microbiota composition and function The stressors reviewed include psychological stress, circadian disruption, sleep deprivation, environmental extremes (high altitude, heat, and cold), environmental pathogens, toxicants, pollutants, and noise, physical activity, and diet (nutrient composition and food restriction) Stressors were selected for their direct relevance to military personnel, a population that is commonly exposed to these stressors, often at extremes, and in combination However, the selected stressors are also common, alone or in combination, in some civilian populations Evidence from preclinical studies collectively indicates that the reviewed stressors alter the composition, function and metabolic activity of the gut microbiota, but that effects vary across stressors, and can include effects that may be beneficial or detrimental to host health Translation of these findings to humans is largely lacking at present This gap precludes concluding with certainty that transient or cumulative exposures to psychological, environmental, and physical stressors have any consistent, meaningful impact on the human gut microbiota However, provocative preclinical evidence highlights a need for translational research aiming to elucidate the impact of stressors on the human gut microbiota, and how the gut microbiota can be manipulated, for example by using nutrition, to mitigate adverse stress responses

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Effects of Psychological, Environmental and Physical Stressors on the Gut Microbiota

According to the proposed definition by FAO/WHO, probiotics must be alive and abundant once ingested. However, during recent years, new definitions are added to the probiotic terminology such as ‘paraprobiotics’ (dead/inactive cells of probiotics) and ‘postbiotics’ (healthful metabolites of probiotics), because findings have shown that dead cells (intact or ruptured) could also show significant health impacts on human. However, mentioned terms are not accurate and impressive enough to reflect the intended meanings regarding all states of probiotic benefits and it seems that a disturbance and confusion in probiotic glossary has been occurred. As a result, a new terminology based on a new efficient approach and conceptualization is needed for a global agreement and usage. In the present paper, we are honored to propose such terminology to provide mentioned comprehensive approach and terminology for all aspects of probiotic benefits. We are proposing three main classes of probiotic including ‘true probiotic’ (TP) referring to viable and active probiotic cell, ‘pseudo-probiotic’ (PP) referring to viable and inactive cell, in the forms of vegetative or spore (PPV or PPS) and ‘ghost probiotic’ (GP) referring to dead/nonviable cell, in the forms of intact or ruptured (GPI or GPR). Each of these classes are classified into two groups based on their site of action/impact: internal (in vivo) or external (in vitro).

Probiotic: conceptualization from a new approach

Xylan is the second most abundant naturally occurring renewable polysaccharide available on earth. It is a complex heteropolysaccharide consisting of different monosaccharides such as l-arabinose, d-galactose, d-mannoses and organic acids such as acetic acid, ferulic acid, glucuronic acid interwoven together with help of glycosidic and ester bonds. The breakdown of xylan is restricted due to its heterogeneous nature and it can be overcome by xylanases which are capable of cleaving the heterogeneous β-1,4-glycoside linkage. Xylanases are abundantly present in nature (e.g., molluscs, insects and microorganisms) and several microorganisms such as bacteria, fungi, yeast, and algae are used extensively for its production. Microbial xylanases show varying substrate specificities and biochemical properties which makes it suitable for various applications in industrial and biotechnological sectors. The suitability of xylanases for its application in food and feed, paper and pulp, textile, pharmaceuticals, and lignocellulosic biorefinery has led to an increase in demand of xylanases globally. The present review gives an insight of using microbial xylanases as an “Emerging Green Tool” along with its current status and future prospective.

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A detailed overview of xylanases: an emerging biomolecule for current and future prospective

Methods in food analysis.

Role of probiotic Lactobacillus fermentum KKL1 in the preparation of a rice based fermented beverage.

Microbial, saccharifying and antioxidant properties of an Indian rice based fermented beverage

High-altitude (HA) visitors like pilgrims, trackers, scientists and military personnel face a group of nonspecific gastrointestinal (GI) symptoms during acclimatization to hypobaric hypoxia. In order to investigate the alteration of indigenous gastrointestinal microbiota in the development of such GI symptoms, an experiment was conducted for the enumeration of dominant cultivable faecal microbiota of 15 soldiers at base level (Delhi) and during their 15-day acclimatization at 3,505 m HA (Leh). At HA, faecal microbiota analysis revealed that total aerobes decreased significantly with increase of total and facultative anaerobes. The strict anaerobes like Bifidobacterium sp., Bacteroidetes sp. and Lactobacillus sp. exhibited positive growth direction index (GDI) like other predominant obligate anaerobes Clostridium perfringens and Peptostreptococcus sp. Different enzymes like amylase, proteinase and polyphenol hydrolase produced by different bacterial populations showed positive GDI, whereas phosphatase producers exhibited negative GDI. The levels of microbe-originated enzymes like amylase, proteinase, alkaline phosphatase and β-glucuronidase were also elevated during HA acclimatization. In addition, in vitro gas production ability was enhanced with increase of faecal immunoglobulins IgA and IgG. We demonstrated that hypoxic environment at HA had the potential to alter the gut microbial composition and its activities that may cause GI dysfunctions.

Dynamics of predominant microbiota in the human gastrointestinal tract and change in luminal enzymes and immunoglobulin profile during high-altitude adaptation

Recycling of civic paper waste by enzyme-based technology is nowadays a point of much concern for pollution-less green environment. In this study, the deinking effectiveness of purified xylanase from a newly isolated bacterium was evaluated for recycling of laser jet paper waste. A potent xylanases-producing bacterium from the microbial consortia of termite gut was isolated, which was further identified on the basis of 16S rRNA sequence as Bacillus sp. CKBx1D. In submerged fermentation condition, the isolate produced the highest level of xylanase (480 U/ml) at 36 h of growth. The extracellular xylanase system comprises of three distinct isozymes (est. Mw 35.28, 28.63, 18.94 kDa). The deinking of laser printed paper waste was performed using the purified enzyme mixture. Whole operational parameters were optimized using the Response Surface Methodology; it was found that at pH 6.8 with 47.2 h of continuous shaking at constant temperature of 35 °C, enzymes showed best deinking activity. After enzyme treatment, the physical properties of the pulp like brightness and ERIC (effective residual ink content) values were enhanced, whereas the pulp opacity was more reduced than the control treatment. Hence, the bacterial isolate and its xylanolytic enzyme system could efficiently be used in recycling paper waste as deinking agent.

Atanu Adak

Papers

An insight into gut microbiota and its functionalities.

Role of probiotic Lactobacillus fermentum KKL1 in the preparation of a rice based fermented beverage.

Microbial, saccharifying and antioxidant properties of an Indian rice based fermented beverage

Dynamics of predominant microbiota in the human gastrointestinal tract and change in luminal enzymes and immunoglobulin profile during high-altitude adaptation

Xylanase Isozymes from the Newly Isolated Bacillus sp. CKBx1D and Optimization of Its Deinking Potentiality