Microbial lipases : at the interface of aqueous and non-aqueous media: a review

In recent times, biotechnological applications of microbial lipases in synthesis of many organic molecules have rapidly increased in non-aqueous media. Microbial lipases are the working horses' in biocatalysis and have been extensively studied when their exceptionally high stability in non-aqueous media has been discovered. Stability of lipases in organic solvents makes them commercially feasibile in the enzymatic esterification reactions. Their stability is affected by temperature, reaction medium, water concentration and by the biocatalyst's preparation. An optimization process for ester synthesis from pilot scale to industrial scale in the reaction medium is discussed. The water released during the esterification process can be controlled over a wide range and has a profound effect on the activity of the lipases. Approaches to lipase catalysis like protein engineering, directed evolution and metagenome approach were studied. This review reports the recent development in the field of non-aqueous microbial lipase catalysis and factors controlling the esterification/transesterification processes in organic media.

Microbial biosynthesis of biopolymers and applications in the biopharmaceutical, biomedical and food industries

Biopolymers can be produced through a variety of mechanisms. They can be derived from microbial systems, extracted from higher organisms such as plants, or synthesized chemically from basic biological building blocks. A wide range of emerging applications rely on all three of these production techniques. In recent years, considerable attention has been given to biopolymers produced by microbes. It is on the microbial level where the tools of genetic engineering can be most readily applied. A number of novel materials are now being developed or introduced into the market. Biopolymers are being developed for use as medical materials, packaging, cosmetics, food additives, clothing fabrics, water treatment chemicals, industrial plastics, absorbents, biosensors, and even data storage elements. This review identifies the possible commercial applications and describes the various methods of production of microbial biopolymers.

Anti-microbial activities of novel nanoformulated lactoferrin through oral administration

A biomolecular delivery system consisting of a novel alginate enclosed, chitosan coated ceramic antimicrobial nanocarrier containing lactoferrin (AEC-CP-Fe-bLf) and development of this multifunctional bovine iron saturated lactoferrin nanotechnology based drug delivery systems for finding treatment to parasitic and bacterial diseases was prepared. Since lactoferrin is a naturally occurring molecule its clinical application would be welcome.

Towards integrated anti-microbial capabilities: Novel bio-fouling resistant membranes by high velocity embedment of silver particles

Biofilm formation on membranes during water desalination operation and pre-treatments limits performance and causes premature membrane degradation. Here, we apply a novel surface modification technique to incorporate anti-microbial metal particles into the outer layer of four types of commercial polymeric membranes by cold spray. The particles are anchored on the membrane surface by partial embedment within the polymer matrix. Although clear differences in particle surface loadings and response to the cold spray were shown by SEM, the hybrid micro-filtration and ultra-filtration membranes were found to exhibit excellent anti-bacterial properties. Poly(sulfone) ultra-filtration membranes were used as for cross-flow filtration of Escherichia coli bacteria solutions to investigate the impact of the cold spray on the material[U+05F3]s integrity. The membranes were characterized by SEM-EDS, FT-IR and TGA and challenged in filtration tests. No bacteria passed through the membrane and filtrate water quality was good, indicating the membranes remained intact. No intact bacteria were found on hybrid membranes, loaded with up to 15. wt% silver, indicating the treatment was lysing bacteria on contact. However, permeation of the hybrid membranes was found to be reduced compared to control non-modified poly(sulfone) membranes due to the presence of the particles across the membrane material. The implementation of cold spray technology for the modification of commercial membrane products could lead to significant operational savings in the field of desalination and water pre-treatments.

N-fixing trees in restoration plantings: effects on nitrogen supply and soil microbial communities

Mixed-species restoration tree plantings are being established increasingly, contributing to mitigate climate change and restore ecosystems. Including nitrogen (N)-fixing tree species may increase carbon (C) sequestration in mixed-species plantings, as these species may substantially increase soil C beneath them. We need to better understand the role of N-fixers in mixed-species plantings to potentially maximize soil C sequestration in these systems. Here, we present a field-based study that asked two specific questions related to the inclusion of N-fixing trees in a mixed-species planting: 1) Do non-N-fixing trees have access to N derived from fixation of atmospheric N2 by neighbouring N-fixing trees? 2) Do soil microbial communities differ under N-fixing trees and non-N-fixing trees in a mixed-species restoration planting? We sampled leaves from the crowns, and litter and soils beneath the crowns of two N-fixing and two non-N-fixing tree species that dominated the planting. Using the 15N natural abundance method, we found indications that fixed atmospheric N was utilized by the non-N-fixing trees, most likely through tight root connections or organic forms of N from the litter layer, rather than through the decomposition of N-fixers litter. While the two N-fixing tree species that were studied appeared to fix atmospheric N, they were substantially different in terms of C and N addition to the soil, as well as microbial community composition beneath them. This shows that the effect of N-fixing tree species on soil carbon sequestration is species-specific, cannot be generalized and requires planting trails to determine if there will be benefits to carbon sequestration. © 2014 Elsevier Ltd.

Recent insights into microbial catalases: isolation, production and purification

Catalase, an oxidoreductase enzyme, works as a detoxification system inside living cells against reactive oxygen species formed as a by-product of different metabolic reactions. The enzyme is found in a wide range of aerobic and anaerobic organisms. Catalase has also been employed in various analytical and diagnostic methods in the form of biosensors and biomarkers in addition to its other applications in textile, paper, food and pharmaceutical industries. New applications for catalases are constantly emerging thanks to their high turnover rate, distinct evolutionary origin, relatively simple and well-defined reaction mechanisms. The following review provides comprehensive information on isolation, production and purification of catalases with different techniques from various microbial sources along with their types, structure, mechanism of action and applications.

Characterization of the extracellular polymeric substances and microbial community of aerobic granulation sludge exposed to cefalexin

This study characterizes the extracellular polymeric substances and bacterial community composition of aerobic granules exposed to cefalexin (CLX). The presence of CLX potentially decreases granular stabilities, resulting in a lowered granule diameter. Chemical oxygen demand and NH4+-N removal efficiencies were slightly decreased and the denitrification process was inhibited with CLX addition. Extracellular polymeric substance contents were significantly increased in aerobic granules exposed to CLX. The shifts of fluorescence intensities and peak locations in 3D-EEM fluorescence spectra indicated changes of EPS components. High-throughput sequencing analysis showed aerobic granules with CLX addition in synthetic wastewater had superior diversity of microbial species, and this was the reason that the level and components of EPS changed. The species richness for bacteria was increased from 341 to 352, which was revealed by Chao1. The Shannon index of diversity rose slightly from 3.59 to 3.73 with CLX addition. The abundance of Proteobacteria significantly decreased, while the abundance of Bacteroidetes and Chloroflexi underwent a highly significant increase in aerobic granules exposed to CLX.

Biotechnological applications of microbial bioconversions

Modern research has focused on the microbial transformation of a huge variety of organic compounds to obtain compounds of therapeutic and/or industrial interest. Microbial transformation is a useful tool for producing new compounds, as a consequence of the variety of reactions for natural products. This article describes the production of many important compounds by biotransformation. Emphasis is placed on reporting the metabolites that may be of special interest to the pharmaceutical and biotechnological industries, as well as the practical aspects of this work in the field of microbial transformations.