Marine Microbes as a Potential Source of Cellulolytic Enzymes

Author(s):  
N. Trivedi ◽  
C.R.K. Reddy ◽  
A.M. Lali
2015 ◽  
Vol 7 (2) ◽  
pp. 625-630 ◽  
Author(s):  
Monica Sachdeva Taggar

Alternative and renewable fuels derived from lignocellulosic biomass offer the potential to reduce our dependence on fossil fuels and mitigate global climate change. Cellulose is one of the major structural components in all lignocellulosic wastes and enzymatic depolymerization of cellulose by cellulases is an essential step in bio-ethanol production. Wood-degrading insects are potential source of biochemical catalysts for converting wood lignocellulose into biofuels. Cellulose digestion has been demonstrated in more than 20 insect families representing ten distinct insect orders. Termite guts been have considered as the “world’s smallest bioreactors” since they digest a significant proportion of cellulose (74-99%) and hemicellulose (65-87%) components of lignocelluloses they ingest. The lower termites harbor protistan symbionts in hindgut whereas higher termites lack these in the hind gut. Studies on cellulose digestion in termites and other insects with reference to ligno-cellulose degrading enzymes have been well focused in this review. The studies on insect cellulolytic systems can lead to the discovery of a variety of novel biocatalysts and genes that encode them, as well as associated unique mechanisms for efficient biomass conversion into biofuels.


2021 ◽  
Vol 21 (11) ◽  
pp. 9031-9045
Author(s):  
Charlotte M. Beall ◽  
Jennifer M. Michaud ◽  
Meredith A. Fish ◽  
Julie Dinasquet ◽  
Gavin C. Cornwell ◽  
...  

Abstract. Ice-nucleating particles (INPs) represent a rare subset of aerosol particles that initiate cloud droplet freezing at temperatures above the homogenous freezing point of water (−38 ∘C). Considering that the ocean covers 71 % of the Earth's surface and represents a large potential source of INPs, it is imperative that the identities, properties and relative emissions of ocean INPs become better understood. However, the specific underlying drivers of marine INP emissions remain largely unknown due to limited observations and the challenges associated with isolating rare INPs. By generating isolated nascent sea spray aerosol (SSA) over a range of biological conditions, mesocosm studies have shown that marine microbes can contribute to INPs. Here, we identify 14 (30 %) cultivable halotolerant ice-nucleating microbes and fungi among 47 total isolates recovered from precipitation and aerosol samples collected in coastal air in southern California. Ice-nucleating (IN) isolates collected in coastal air were nucleated ice from extremely warm to moderate freezing temperatures (−2.3 to −18 ∘C). While some Gammaproteobacteria and fungi are known to nucleate ice at temperatures as high as −2 ∘C, Brevibacterium sp. is the first Actinobacteria found to be capable of ice nucleation at a relatively high freezing temperature (−2.3 ∘C). Air mass trajectory analysis demonstrates that marine aerosol sources were dominant during all sampling periods, and phylogenetic analysis indicates that at least 2 of the 14 IN isolates are closely related to marine taxa. Moreover, results from cell-washing experiments demonstrate that most IN isolates maintained freezing activity in the absence of nutrients and cell growth media. This study supports previous studies that implicated microbes as a potential source of marine INPs, and it additionally demonstrates links between precipitation, marine aerosol and IN microbes.


Author(s):  
Philippe Fragu

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.


Author(s):  
Е.Н. Ильина ◽  
Е.И. Олехнович ◽  
А.В. Павленко

С течением времени подходы к изучению резистентности к антибиотикам трансформировались от сосредоточения на выделенных в виде чистой культуры патогенных микроорганизмах к исследованию резистентности на уровне микробных сообществ, составляющих биотопы человека и окружающей среды. По мере того, как продвигается изучение устойчивости к антибиотикам, возникает необходимость использования комплексного подхода для улучшения информирования мирового сообщества о наблюдаемых тенденциях в этой области. Все более очевидным становится то, что, хотя не все гены резистентности могут географически и филогенетически распространяться, угроза, которую они представляют, действительно серьезная и требует комплексных междисциплинарных исследований. В настоящее время резистентность к антибиотикам среди патогенов человека стала основной угрозой в современной медицине, и существует значительный интерес к определению ниши, в которых бактерии могут получить гены антибиотикорезистентности, и механизмов их передачи. В данном обзоре мы рассматриваем проблемы, возникшие на фоне широкого использования человечеством антибактериальных препаратов, в свете формирования микрофлорой кишечника резервуара генов резистентности. Over the time, studies of antibiotic resistance have transformed from focusing on pathogenic microorganisms isolated as a pure culture to analysis of resistance at the level of microbial communities that constitute human and environmental biotopes. Advancing studies of antibiotic resistance require an integrated approach to enhance availability of information about observed tendencies in this field to the global community. It becomes increasingly obvious that, even though not all resistance genes can geographically and phylogenetically spread, the threat they pose is indeed serious and requires complex interdisciplinary research. Currently, the antibiotic resistance of human pathogens has become a challenge to modern medicine, which is now focusing on determining a potential source for bacterial genes of drug resistance and mechanisms for the gene transmission. In this review, we discussed problems generated by the widespread use of antibacterial drugs in the light of forming a reservoir of resistance genes by gut microflora.


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