Mangrove soil as a source for novel xylanase and amylase as determined by cultivation-dependent and cultivation-independent methods

Lignocellulolytic Biocatalysts: The Main Players Involved in Multiple Biotechnological Processes for Biomass Valorization

Human population growth, industrialization, and globalization have caused several pressures on the planet's natural resources, culminating in the severe climate and environmental crisis which we are facing. Aiming to remedy and mitigate the impact of human activities on the environment, the use of lignocellulolytic enzymes for biofuel production, food, bioremediation, and other various industries, is presented as a more sustainable alternative. These enzymes are characterized as a group of enzymes capable of breaking down lignocellulosic biomass into its different monomer units, making it accessible for bioconversion into various products and applications in the most diverse industries. Among all the organisms that produce lignocellulolytic enzymes, microorganisms are seen as the primary sources for obtaining them. Therefore, this review proposes to discuss the fundamental aspects of the enzymes forming lignocellulolytic systems and the main microorganisms used to obtain them. In addition, different possible industrial applications for these enzymes will be discussed, as well as information about their production modes and considerations about recent advances and future perspectives in research in pursuit of expanding lignocellulolytic enzyme uses at an industrial scale.

Temperature drives the assembly of Bacillus community in mangrove ecosystem

Mangroves are located at the interface of terrestrial and marine environments, and experience fluctuating conditions, creating a need to better explore the relative role of the bacterial community. Bacillus has been reported to be the dominant group in the mangrove ecosystem and plays a key role in maintaining the biodiversity and function of the mangrove ecosystem. However, studies on bacterial and Bacillus community across four seasons in the mangrove ecosystem are scarce. Here, we employed seasonal large-scale sediment samples collected from the mangrove ecosystem in southeastern China and utilized 16S rRNA gene amplicon sequencing to reveal bacterial and Bacillus community structure changes across seasons. Compared with the whole bacterial community, we found that Bacillus community was greatly affected by season (temperature) rather than site. The key factors, NO₃-N and NH₄-N showed opposite interaction with superabundant taxa Bacillus taxa (SAT) and three rare Bacillus taxa including high rare taxa (HRT), moderate rare taxa (MRT) and low rare taxa (LRT). Network analysis suggested the co-occurrence of Bacillus community and Bacillus-bacteria, and revealed SAT had closer relationship compared with rare Bacillus taxa. HRT might act crucial response during the temperature decreasing process across seasons. This study fills a gap in addressing the assembly of Bacillus community and their role in maintaining microbial diversity and function in mangrove ecosystem.

Characterization of a novel GH10 alkali-thermostable xylanase from a termite microbiome

The aim of the present study was to assess the biochemical and molecular structural characteristics of a novel alkali-thermostable GH10 xylanase (Xyl10B) identified in a termite gut microbiome by a shotgun metagenomic approach. This endoxylanase candidate was amplified, cloned, heterologously expressed in Escherichia coli and purified. The recombinant enzyme was active at a broad range of temperatures (37-60 ºC) and pH values (4-10), with optimal activity at 50 ºC and pH 9. Moreover, its activity remained at more than 80% of its maximum at 50 °C for 8 h. In addition, Xyl10B was found to be stable in the presence of salt and several ions and chemical reagents frequently used in the industry. These characteristics make this enzyme an interesting candidate for pulp and paper bleaching industries, since this process requires enzymes without cellulase activity and resistant to high temperatures and alkaline pH (thermo-alkaliphilic enzymes). The products of xylan hydrolysis by Xyl10B (short xylooligosaccharides, xylose and xylobiose) could be suitable for application as prebiotics and in the production of bioethanol.

Microorganisms: the secret agents of the biosphere, and their key roles in biotechnology

Abstract We present a survey of projects that have been funded by FAPESP under the BIOTA-Microorganisms program. These projects generated a wide variety of results, including the identification of novel antibacterial-producing microorganisms, the characterization of novel microbial enzymes for industrial applications, taxonomic classification of novel microorganisms in several environments, investigation of the soil and mangrove microbial ecosystems and its influence on endangered plant species, and the sequencing of novel metagenome-assembled genomes. The results surveyed demonstrate the importance of microorganisms in environments that play important roles in human activities as well as the potential that many of these microorganisms have in contributing to biotechnological applications crucial for human survival in the 21st century.

Combined characterization of a new member of Marivita cryptomonadis strain LZ-15-2 isolated from cultivable phycosphere microbiota of highly toxic HAB dinoflagellate Alexandrium catenella LZT09

During our conveying the microbial structures of phycosphere microbiota (PM) derived from diverse marine harmful algal bloom (HAB) dinoflagellates, a new rod-sharped, white-colored cultivable bacterial strain, designated as LZ-15-2, was isolated from the PM of highly toxic Alexandrium catenella LZT09. Phylogenetic analysis of 16S rRNA gene sequence indicated that strain LZ-15-2 belonged to the genus Marivita within the family Rhodobacteraceae, and demonstrated the highest gene similarity of 99.2% to M. cryptomonadis CL-SK44^T, and less than 98.65% with other type strains of Marivita. Phylogenomic calculations on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the new isolate and M. cryptomonadis CL-SK44^T were 99.86% and 99.88%, respectively. Genomic comparison of strain LZ-15-2 with available genomes of Marivita species further verified its taxonomic position within the genus of Marivita. Moreover, comparative genomics analysis showed a proximal similarity of strain LZ-15-2 with M. cryptomonadis CL-SK44^T, and it also revealed an open pan-genome status based on constructed gene accumulation curves among Marivita members with 9,361 and 1,712 genes for the pan- and core-genome analysis, respectively. Based on combined polyphasic taxonomic characteristics, strain LZ-15-2 represents a new member of M. cryptomonadis, and proposed as a potential candidate for further exploration of the detailed mechanisms governing the dynamic cross-kingdom algae-bacteria interactions (ABI) between PM and their algal host LZT09.

Genome sequence of an uncharted halophilic bacterium Robertkochia marina with deciphering its phosphate-solubilizing ability

The wide use of whole-genome sequencing approach in the modern genomic era has opened a great opportunity to reveal the prospective applications of halophilic bacteria. Robertkochia marina CC-AMO-30D^T is one of the halophilic bacteria that was previously taxonomically identified without any inspection on its biotechnological potential from a genomic aspect. In this study, we present the whole-genome sequence of R. marina and demonstrated the ability of this bacterium in solubilizing phosphate by producing phosphatase. The genome of R. marina has 3.57 Mbp and contains 3107 predicted genes, from which 3044 are protein coding, 52 are non-coding RNAs, and 11 are pseudogenes. Several phosphatases such as alkaline phosphatases and pyrophosphatases were mined from the genome. Further genomic study (phylogenetics, sequence analysis, and functional mechanism) and experimental data suggested that the alkaline phosphatase produced by R. marina could potentially be utilized in promoting plant growth, particularly for plants on saline-based agricultural land.

Xylanolytic Extremozymes Retrieved From Environmental Metagenomes: Characteristics, Genetic Engineering, and Applications

Xylanolytic enzymes have extensive applications in paper, food, and feed, pharmaceutical, and biofuel industries. These industries demand xylanases that are functional under extreme conditions, such as high temperature, acidic/alkaline pH, and others, which are prevailing in bioprocessing industries. Despite the availability of several xylan-hydrolyzing enzymes from cultured microbes, there is a huge gap between what is available and what industries require. DNA manipulations as well as protein-engineering techniques are also not quite satisfactory in generating xylan-hydrolyzing extremozymes. With a compound annual growth rate of 6.6% of xylan-hydrolyzing enzymes in the global market, there is a need for xylanolytic extremozymes. Therefore, metagenomic approaches have been employed to uncover hidden xylanolytic genes that were earlier inaccessible in culture-dependent approaches. Appreciable success has been achieved in retrieving several unusual xylanolytic enzymes with novel and desirable characteristics from different extreme environments using functional and sequence-based metagenomic approaches. Moreover, the Carbohydrate Active Enzymes database includes approximately 400 GH-10 and GH-11 unclassified xylanases. This review discusses sources, characteristics, and applications of xylanolytic enzymes obtained through metagenomic approaches and their amelioration by genetic engineering techniques.