Pretreatment of lignocelluloses for enhanced biogas production: A review on influencing mechanisms and the importance of microbial diversity

Received 13 August 2019; Received in revised form 10 July 2020; Accepted 28 July 2020, Available online 11 August 2020.As one of the most efficient methods for waste management and sustainable energy production, anaerobic digestion (AD) countenances difficulties in the hydrolysis of lignocelluloses biomass. Different pretreatment methods have been applied to make lignocelluloses readily biodegradable by microorganisms. These pretreatments can affect biogas yield by different mechanisms at molecular scale, including changes in chemical composition, cellulose crystallinity, degree of polymerization, enzyme adsorption/desorption, nutrient accessibility, deacetylation, and through the formation of inhibitors. The present article aims at critically reviewing the reported molecular mechanisms affecting biogas yield from lignocelluloses via different types of pretreatments. Then, a new hypothesis concerning the impact of pretreatment on the microbial community developed (throughout the AD process from an identical inoculum) was also put forth and was experimentally examined through a case study. Four different leading pretreatments, including sulfuric acid, sodium hydroxide, aqueous ammonia, and sodium carbonate, were performed on rice straw as model lignocellulosic feedstock. The results obtained revealed that the choice of pretreatment method also plays a pivotally positive or negative role on biogas yield obtained from lignocelluloses through alteration of the microbial community involved in the AD. Considerable changes were observed in the archaeal and bacterial communities developed in response to the pretreatment used. Sodium hydroxide, with the highest methane yield (338 mL/g volatile solid), led to a partial switch from acetoclastic to the hydrogenotrophic methane production pathway. The findings reported herein undermine the default hypothesis accepted by thousands of previously published papers, which is changes in substrate characteristics by pretreatments are the only mechanisms affecting biogas yield. Moreover, the results obtained could assist with the development of more efficient biogas production systems at industrial scale by offering more in-depth understanding of the interactions between microbial community structure, and process parameters and performance

Morphological identification and molecular validation of anchovies (Engraulidae) in the Persian Gulf and Oman Sea

Afrand, Mahboobeh, Sourinejad, Iman, Fazeli, Seyed Abolhassan Shahzadeh, Akbarzadeh, Arash, Yeganeh, Laleh Parsa, Sadeghi, Maryam, Azarbaijani, Reza (2020): Morphological identification and molecular validation of anchovies (Engraulidae) in the Persian Gulf and Oman Sea. Zootaxa 4742 (2): 375-391, DOI: 10.11646/zootaxa.4742.2.1

Genome-Wide Analysis of Oceanimonas sp. GK1 Isolated from Gavkhouni Wetland (Iran) Demonstrates Presence of Genes for Virulence and Pathogenicity

Objective: The bacterium Oceanimonas sp. (O. sp.) GK1 is a member of the Aeromonadaceae family and its genome represents several virulence genes involved in fish and human pathogenicity. In this original research study we aimed to identify and characterize the putative virulence factors and pathogenicity of this halotolerant marine bacterium using genome wide analysis. Materials and Methods: The genome data of O. sp. GK1 was obtained from NCBI. Comparative genomic study was done using MetaCyc database. Results: Whole genome data analysis of the O. sp. GK1 revealed that the bacterium possesses some important virulence genes (e.g. ZOT, RTX toxin, thermostable hemolysin, lateral flagella and type IV pili) which have been implicated in adhesion and biofilm formation and infection in some other pathogenic bacteria. Conclusion: This is the first report of the putative pathogenicity of O. sp.GK1. The genome wide analysis of the bacterium demonstrates the presence of virulence genes causing infectious diseases in many warm- and cold-blooded animals

Data Walker 1862

<i>Data analysis</i> <p> Forward and reverse sequences were assembled and manually edited using the SeqMan software (DNAStar). We added to our dataset the COI sequences of <i>Chirocentrus dorab</i>, <i>Dussumieria acuta</i>, <i>Nematalosa nasus</i>, <i>Sardinella albella</i>, and <i>Sardinella gibbosa</i> (non-engraulid Clupeoidei) and <i>Denticeps clupeoides</i> (Denticipoidei) as out group to root our phylogenetic tree. All sequences were aligned using CLUSTAL W (Thompson <i>et al.</i> 1994) in Meg Align software (DNAStar) and variable sites were determined. Pairwise sequence divergence was calculated by using Kimura’s two-parameter (K2P) distance (Kimura 1980). Maximum Likelihood (ML) trees with bootstrap analysis of 1000 replicates based on K2P distance were constructed in MEGA version 6.0 (Tamura <i>et al.</i> 2013).</p>Published as part of <i>Afrand, Mahboobeh, Sourinejad, Iman, Fazeli, Seyed Abolhassan Shahzadeh, Akbarzadeh, Arash, Yeganeh, Laleh Parsa, Sadeghi, Maryam & Azarbaijani, Reza, 2020, Morphological identification and molecular validation of anchovies (Engraulidae) in the Persian Gulf and Oman Sea, pp. 375-391 in Zootaxa 4742 (2)</i> on page 377, DOI: 10.11646/zootaxa.4742.2.10, <a href="http://zenodo.org/record/3677781">http://zenodo.org/record/3677781</a&gt