Integrative transcriptome and proteome revealed high-yielding mechanisms of epsilon-poly-L-lysine by .

Introduction: ε-poly-L-lysine (ε-PL) is a high value, widely used natural antimicrobial peptide additive for foods and cosmetic products that is mainly produced by . In previous work, we developed the high-yield industrial strain WG-608 through successive rounds of engineering.

Methods: Here, we use integrated physiological, transcriptomic, and proteomics association analysis to resolve the complex mechanisms underlying high ε-PL production by comparing WG-608 with the progenitor strain M-Z18.

Epsilon-poly-L-lysine: Recent Advances in Biomanufacturing and Applications.

ε-poly-L-lysine (ε-PL) is a naturally occurring poly(amino acid) of varying polymerization degree, which possesses excellent antimicrobial activity and has been widely used in food and pharmaceutical industries. To provide new perspectives from recent advances, this review compares several conventional and advanced strategies for the discovery of wild strains and development of high-producing strains, including isolation and culture-based traditional methods as well as genome mining and directed evolution. We also summarize process engineering approaches for improving production, including optimization of environmental conditions and utilization of industrial waste.

Extraction and purification of ε-poly-l-lysine from fermentation broth using an ethanol/ammonium sulfate aqueous two-phase system combined with ultrafiltration.

ε-Poly-l-lysine (ε-PL) serves as a natural food preservative and is manufactured mainly by extraction from microbial fermentation broth using ion-exchange chromatography. In order to develop an alternative purification strategy, an environmentally friendly alcohol/salt aqueous two-phase system (ATPS) was explored in this study for ε-PL extraction. A study of the separation of ε-PL in different alcohol/salt systems showed that ethanol/ammonium sulfate ATPS exhibited the highest ε-PL partition coefficient and recovery ratio.

Mechanisms of response to pH shock in microbial fermentation.

The following review highlights pH shock, a novel environmental factor, as a tool for the improvement of fermentation production. The aim of this review is to introduce some recent original studies on the enhancement of microbial fermentation production by pH shock. Another purpose of this review is to improve the understanding of the processes that underlie physiological and genetic differences, which will facilitate future research on the improvement of fermentation production and reveal the associated molecular mechanisms.

Understanding high ε-poly-L-lysine production by Streptomyces albulus using pH shock strategy in the level of transcriptomics.

ε-Poly-L-lysine (ε-PL) is a natural food preservative, which exhibits antimicrobial activity against a wide spectra of microorganisms. The production of ε-PL was significantly enhanced by pH shock in our previous study, but the underlying mechanism is poorly understood. According to transcriptional and physiological analyses in this study, the mprA/B and pepD signal transduction system was first proved to be presented and activated in Streptomyces albulus M-Z18 by pH shock, which positively regulated the transcription of ε-PL synthetase (Pls) gene and enhanced the Pls activity during fermentation.

Differential protein expression of a streptomycin-resistant mutant in high yield production of ε-poly-l-lysine: a proteomics study.

ε-Poly-l-lysine (ε-PL), produced by , is an excellent antimicrobial agent which has been extensively used in the field of food and medicine. In our previous study, we have improved ε-PL production by M-Z18 through iterative introduction of streptomycin resistance. To decipher the overproduction mechanism of high-yielding mutant SS-62, we conducted a comparative proteomics analysis between SS-62 and its parent strain M-Z18.

Effect of ion form of the ion-exchange resin on ε-poly-l-lysine purification from microbial fermentation broth.

ε-Poly-l-lysine (ε-PL) is an added-value natural product with widespread application in the fields of food, pharmaceuticals and biopolymer materials. However, the high production cost reduces its application. To improve the efficiency of ε-PL purification for decreasing the cost of downstream processes, the ion form of the ion-exchange resin, which is widely used for ε-PL purification, was investigated systematically in this study.

Transcriptional study of the enhanced ε-poly-L-lysine productivity in culture using glucose and glycerol as a mixed carbon source.

A glucose-glycerol mixed carbon source (MCS) can substantially reduce batch fermentation time and improve ε-poly-L-lysine (ε-PL) productivity, which was of great significance in industrial microbial fermentation. This study aims to disclose the physiological mechanism by transcriptome analyses. In the MCS, the enhancements of gene transcription mainly emerged in central carbon metabolism, L-lysine synthesis as well as cell respiration, and these results were subsequently proved by quantitative real-time PCR assay.

Efficiently activated ε-poly-L-lysine production by multiple antibiotic-resistance mutations and acidic pH shock optimization in Streptomyces albulus.

ε-Poly-L-lysine (ε-PL) is a food additive produced by Streptomyces and is widely used in many countries. Working with Streptomyces albulus FEEL-1, we established a method to activate ε-PL synthesis by successive introduction of multiple antibiotic-resistance mutations. Sextuple mutant R6 was finally developed by screening for resistance to six antibiotics and produced 4.

Metabolic analyses of the improved ε-poly-L-lysine productivity using a glucose-glycerol mixed carbon source in chemostat cultures.

The glucose-glycerol mixed carbon source remarkably reduced the batch fermentation time of ε-poly-L-lysine (ε-PL) production, leading to higher productivity of both biomass and ε-PL, which was of great significance in industrial microbial fermentation. Our previous study confirmed the positive influence of fast cell growth on the ε-PL biosynthesis, while the direct influence of mixed carbon source on ε-PL production was still unknown. In this work, chemostat culture was employed to study the capacity of ε-PL biosynthesis in different carbon sources at a same dilution rate of 0.

Insights into the simultaneous utilization of glucose and glycerol by Streptomyces albulus M-Z18 for high ε-poly-L-lysine productivity.

The simultaneous consumption of glucose and glycerol led to remarkably higher productivity of both biomass and ε-poly-L-lysine (ε-PL), which was of great significance in industrial microbial fermentation. To further understand the superior fermentation performances, transcriptional analysis and exogenous substrates addition were carried out to study the simultaneous utilization of glucose and glycerol by Streptomyces albulus M-Z18. Transcriptome analysis revealed that there was no mutual transcriptional suppression between the utilization of glucose and glycerol, which was quite different from typical "glucose effect".

Development of Microtiter Plate Culture Method for Rapid Screening of ε-Poly-L-Lysine-Producing Strains.

ε-Poly-L-lysine (ε-PL) produced by Streptomyces albulus possesses a broad spectrum of antimicrobial activity and is widely used as a food preservative. To extensively screen ε-PL-overproducing strain, we developed an integrated high-throughput screening assay using ribosome engineering technology. The production protocol was scaled down to 24- and 48-deep-well microtiter plates (MTPs).

Novel process combining anaerobic-aerobic digestion and ion exchange resin for full recycling of cassava stillage in ethanol fermentation.

A novel cleaner ethanol production process has been developed. Thin stillage is treated initially by anaerobic digestion followed by aerobic digestion and then further treated by chloride anion exchange resin. This allows the fully-digested and resin-treated stillage to be completely recycled for use as process water in the next ethanol fermentation batch, which eliminates wastewater discharges and minimizes consumption of fresh water.

Effect of acetic acid in recycling water on ethanol production for cassava in an integrated ethanol-methane fermentation process.

Recently, the integrated ethanol-methane fermentation process has been studied to prevent wastewater pollution. However, when the anaerobic digestion reaction runs poorly, acetic acid will accumulate in the recycling water. In this paper, we studied the effect of low concentration of acetic acid (≤25 mM) on ethanol fermentation at different initial pH values (4.

Enhanced ε-poly-L-lysine production by inducing double antibiotic-resistant mutations in Streptomyces albulus.

ε-Poly-L-lysine (ε-PL), as a food additive, has been widely used in many countries. However, its production still needs to be improved. We successfully enhanced ε-PL production of Streptomyces albulus FEEL-1 by introducing mutations related to antibiotics, such as streptomycin, gentamicin, and rifampin.

Ethanol fermentation characteristics of recycled water by Saccharomyces cerevisiae in an integrated ethanol-methane fermentation process.

An process of integrated ethanol-methane fermentation with improved economics has been studied extensively in recent years, where the process water used for a subsequent fermentation of carbohydrate biomass is recycled. This paper presents a systematic study of the ethanol fermentation characteristics of recycled process water. Compared with tap water, fermentation time was shortened by 40% when mixed water was employed.

[Breeding and fermentation performance of a high-yield ε-poly-Llysine producing strain].

Objective: A high yield of ε-poly-L-lysine (ε-PL) producing strain was bred, and the effect of different carbon sources on fermentation performance was studied.

Methods: Genome shuffling and ribosome engineering were used to enhanced strain's productivity, and pH shock strategy was used to fermentation using different carbon sources.

Results: After four rounds of genome shuffling and ribosome engineering, we obtained a high yield mutant Streptomyces albulus GS114 with ε-PL productivity of 3.

Genome Shuffling and Gentamicin-Resistance to Improve ε-Poly-L-Lysine Productivity of Streptomyces albulus W-156.

Genome shuffling has been a recently effective method for screening the desirable phenotypes of industrial strains. Here, we combined genome shuffling and gentamicin resistance to improve the production of ε-poly-L-lysine in Streptomyces albulus W-156. Five starting mutants with higher ε-poly-L-lysine (ε-PL) productivities were firstly obtained by atmospheric and room temperature plasma (ARTP) mutagenesis.

A novel cleaner production process of citric acid by recycling its treated wastewater.

In this study, a novel cleaner production process of citric acid was proposed to completely solve the problem of wastewater management in citric acid industry. In the process, wastewater from citric acid fermentation was used to produce methane through anaerobic digestion and then the anaerobic digestion effluent was further treated with air stripping and electrodialysis before recycled as process water for the later citric acid fermentation. This proposed process was performed for 10 batches and the average citric acid production in recycling batches was 142.

Effect of propionic acid on citric acid fermentation in an integrated citric acid-methane fermentation process.

In this study, an integrated citric acid-methane fermentation process was established to solve the problem of wastewater treatment in citric acid production. Citric acid wastewater was treated through anaerobic digestion and then the anaerobic digestion effluent (ADE) was further treated and recycled for the next batch citric acid fermentation. This process could eliminate wastewater discharge and reduce water resource consumption.

[Enhanced ε-poly-L-lysine production through pH regulation and organic nitrogen addition in fed-batch fermentation].

During the production of ε-poly-L-lysine (ε-PL) in fed-batch fermentation, the decline of ε-PL synthesis often occurs at middle or late phase of the fermentation. To solve the problem, we adopted two strategies, namely pH shift and feeding yeast extract, to improve the productivity of ε-PL. ε-PL productivity in fermentation by pH shift and feeding yeast extract achieved 4.

Physiological mechanism of the overproduction of ε-poly-L-lysine by acidic pH shock in fed-batch fermentation.

The introduction of an environmental stress of acidic pH shock had successfully solved the common deficiency existed in ε-PL production, viz. the distinct decline of ε-PL productivity in the feeding phase of the fed-batch fermentation. To unravel the underlying mechanism, we comparatively studied the physiological changes of Streptomyces sp.

Enhancement of ε-poly-lysine production in ε-poly-lysine-tolerant Streptomyces sp. by genome shuffling.

ε-Poly-L-lysine (ε-PL) has been widely used as food additive. However, the self-inhibition of ε-PL on cell growth limits the accumulation of ε-PL in the wild-type strain. Here, we screened ε-PL-tolerant strain of Streptomyces sp.

Cleaner production of citric acid by recycling its extraction wastewater treated with anaerobic digestion and electrodialysis in an integrated citric acid-methane production process.

To solve the pollution problem of extraction wastewater in citric acid production, an integrated citric acid-methane production process was proposed. Extraction wastewater was treated through anaerobic digestion and the anaerobic digestion effluent (ADE) was recycled for the next batch of citric acid fermentation, thus eliminating wastewater discharge and reducing water consumption. Excessive Na(+) contained in ADE could significantly inhibit citric acid fermentation in recycling and was removed by electrodialysis in this paper.