Retting Of Flax Research Articles

Isolation and identification of Chlorella sorokiniana HDMA-16 and its cultivation potential in flax retting wastewater

The utilization of microalgae for wastewater treatment presents a promising and cost-effective solution due to their ability to remove pollutants while simultaneously synthesizing biomass from wastewater nutrients. This research identified a novel strain of Chlorella sorokiniana and investigated its growth ability in flax retting wastewater (FRW), as well as its potential for FRW treatment. Chlorella sorokiniana HDMA-16 was inoculated into FRW, both with and without additional nutrient supplementation. The biomass, lipid content, and fatty acid profile of Chlorella sorokiniana HDMA-16 were determined, along with the changes in total nitrogen (TN), ammonia nitrogen (NH4+-N), total phosphorus (TP), and chemical oxygen demand (COD) in FRW. The results revealed that Chlorella sorokiniana HDMA-16 exhibited moderate growth in FRW without the need for additional nutrients. The strain achieved maximum biomass and lipid productivity levels of 785.7 mg L−1 and 151.5 RFU L−1 d−1. The lipid produced by Chlorella sorokiniana HDMA-16 displayed a favorable fatty acid profile, making the strain a potential candidate for the synthesis of by-products such as biodiesel. The removal rates of NH4+-N, TP, and COD in FRW reached a maximum of 26.86 %, 99.59 %, and 29.39 %. This study is significant in that it shows that the newly discovered Chlorella sorokiniana HDMA-16 can thrive in FRW and effectively remove pollutants. These findings provide a novel approach for FRW treatment and the large-scale cultivation of microalgae, offering promising prospects for sustainable wastewater treatment and microalgae-based industries.

Response characteristics of flax retting liquid addition during chicken manure composting: Focusing on core bacteria in organic carbon mineralization and humification

To explore the applicability of flax retting liquid (FRL) addition, the physicochemical properties, microbial community structure and function, carbon conversion and humus (HS) formation were assessed during chicken manure (CM) aerobic composting. Compared with the control group, the addition of FRL increased the temperature at thermophilic phase, while the microbial mass carbon content (MBC) in SCF and FRH groups raised to 96.1 ± 0.25 g/Kg and 93.33 ± 0.27 g/Kg, respectively. Similarly, FRL also improved the concent of humic acid (HA) to 38.44 ± 0.85 g/Kg, 33.06 ± 0.8 g/Kg, respcetively. However, fulvic acid (FA) decreased to 30.02 ± 0.55 g/Kg, 31.4 ± 0.43 g/Kg, respectively and further reduced CO2 emissions. FRL influenced the relative abundance of Firmicutes at thermophilic phase and Ornithinimicrobium at maturity phase. Additionally, FRL strengthen the association among flora and reduce the number of bacteria, which was negative correlated with HA and positive with CO2 during composting. These findings offer powerful technological support for improving agricultural waste recycling.

Effect of Warm-Water Retting Pretreatment on the Physical Properties of Banana Stem and Its Fibre

In this paper, warm-water flax retting was used as a pretreatment method for banana-fibre extraction. To determine the optimum conditions for flax retting, the physical properties of various parts of stems and fibres in the process of flax retting were analysed. By studying the tensile strength, elongation at break, diameter, moisture regain, and other characteristics of the fibres, the influences of bacteria and enzymes in the retting liquor on the fibre characteristics in different retting stages were determined. Through mechanical-property tests and microscopic observation of the stem skin, the change rules of the mechanical properties and degumming state of the stems were examined. The results showed that the fibre tensile strength of banana stems reached the maximum value of 45 ± 16 cN·tex-1 after 11 days of retting. As most resins had not been hydrolysed, fibre extraction was difficult. After 21-25 days of retting, the tensile strength of fibres was about 34 ± 10 cN·tex-1, elongation at break was about 1.71%, and moisture regain was about 13.56%. The fibre characteristics met the process requirements, and the tensile separation stress of the stem was small, about 0.034 MPa. This time point could be used as the optimum endpoint for retting flax in warm water, which could provide theoretical support and research basis for the recycling of banana straw. The functional groups of the extracted fibres were studied by FTIR, which confirmed the observed change rule of each component during degumming. The experimental results showed that a longer retting time corresponded with a lower content of fibre impurities, more thorough degumming, and less difficult extraction; however, strength and toughness decreased.

The Influence of Water Hardness on the Agronomic Traits of Foreign Fibre Flax Varieties in the Republic of Croatia

The amount and quality of fibres depend on a whole range of factors, the most important being variety, agroecological conditions, agrotechnics and the degree of fibre flax plant maturity, the purpose for which flax is grown, retting and processing. The retting of fibre flax is the most complex stage in the processing of flax into fibre. The aim of this study was to gain knowledge about the acclimatization ability of foreign varieties that can potentially be adapted to climatic in Republic Croatia. Therefore, this paper presents the results of achieved agronomic traits (dry stem yield, dry stem after retting, total fibre yield, long fibre yield, share of total fibre and share of long fibre) of five foreign varieties of fibre flax. The selected varieties were retted in very soft, medium hard and hard water. Variety trials with fibre flax were set up over three years (2012–2014) at two locations (Zagreb) on anthropogenized eutric cambisol and (Križevci) on pseudogley on level terrain. The trials were carried out according to the RCBD in four replications. According to the results of the three-year research into the agronomic traits of fibre flax, significant differences were identified among the varieties studied. The varieties Agatha, Viola and Electra recorded the highest values of studied traits. Statistically significant differences were only recorded among different water hardness for long fibre yield in 2012 and share of total fibre in 2013 in Zagreb. The highest yields and share of fibres were recorded when the fibre flax was retted in very soft water.

Enhanced β-mannanase production by Bacillus licheniformis by optimizing carbon source and feeding regimes

Bacillus licheniformis HDYM-04 was isolated in flax retting water and showed β-mannanase activity. Carbon sources for β-mannanase production, as well as the fermentation conditions and feeding strategy, were optimized in shake flasks. When glucose or konjac powder was used as the carbon source, the β-mannanase activity was 288.13 ± 21.59 U/mL and 696.35 ± 23.47 U/mL at 24 h, respectively, which was approximately 4.4- to 10.68-fold higher than the values obtained with wheat powder. When 0.5% (w/v) glucose and 1% (w/v) konjac powder were added together, maximum enzyme activities of 789.07 ± 25.82 U/mL were obtained, an increase of 13.35% compared to the unoptimized cultures with only 1% (w/v) konjac powder. The enzyme activity decreased in the presence of 1% (w/v) konjac powder, but the highest enzyme activity was 1,533.26 ± 33.74 U/mL, a 1.2-fold increase compared with that in nonoptimized cultures; when 0.5% (w/v) glucose was used, the highest enzyme activity was 966.53 ± 27.84 U/mL, an increase in β-mannanase activity of 38.79% compared with control cultures. In this study, by optimizing fed-batch fermentation conditions, the yield of β-mannanase produced by HDYM-04 was increased, laying the foundation for the industrial application and further research of B. licheniformis HDYM-04.

Quality optimization of flax fibre through durational management of water retting technology under sub-tropical climate

The ascendancy of flax fibre strongly depends on the duration and process of its retting. In sub-tropical areas, warm and dry season quickly following the cold flax growing season does not allow dew retting of flax. Hence, development of suitable retting technology is utmost need under such climate. Therefore, an experiment was designed with seven tank-retting durational treatments [0 day (unretted), 1 day, 2 days, 4 days, 6 days, 8 days and 10 days] to find out the best retting period. The data revealed that the rate of weight loss was augmented upto fourth day of retting, while, rate of pectin loss was the highest on the second day of retting. Overall, it was also observed that the best quality flax-fibre was obtained with tank-water retting of 4–6 days. Retting of less than 4 days resulted in lower degumming, higher non-cellulosic material, while, more than 6 days caused over retting owing to poor quality fibre.

Microwave pretreated enzymatic retting of flax stems and comparison with the effect of radio frequency pretreatment

Microwave (MW) together with prior water presoaking was used as a pretreatment for enzymatic retting of flax stems in this work. Weight loss, pectin removal, the resulting fibers’ properties and the degree of water absorption of the stems after MW pretreatment were measured and analyzed. The effect of MW pretreatment on enzymatic retting was determined and compared with the radio frequency (RF) pretreatment which adopted the same processing parameters. It was found that the 8 h-30 min MW pretreatment improved the enzymatic retting efficiency most, increasing weight loss by 39 %, decreasing pectin content by 10.96 % compared to the control enzymatic retting and obtaining water sorption of 2.23, and produced fibers with reasonable tensile performance. Compared with RF pretreatment, MW pretreatment enabled flax to absorb more water and more energy then got more improvement in the retting efficiency. And the 30 min-MW treatment could improve pectin removal for the non-presoaked flax as compared to the control enzymatic retting, which was different from RF treatment. The enzyme-retted fibers with the same MW and RF pretreatments had close tensile properties, however, their values of the MW-pretreated fibers tended to be slightly lower. It was also found that the tensile performance of the pretreated, enzyme-retted fibers was linked to the amount of energy absorbed, the temperature-maintaining time proportion during MW or RF treatment, and whether the flax had been presoaked or not.

Highly efficient fungal pectinase and laccase producers among isolates from flax retting liquor

The retting of flax straw depends on specific enzymes capable to separate the fibers from the plant straw. Among these enzymes pectinase and laccase play the most significant part of the process. In a previous study, the bacterial pectinase was studied to assess its role in decolouring and degumming of flax straw. In this study, the fungal pectinase and laccase were evaluated in relation to the flax retting and fiber quality. Ten fungi isolated were obtained from the flax retting chamber. These isolates were identified to species level by Biolog. The results showed that every isolate belonged to certain fungal species. The species are as follow: Aspergillus terricola, Aspergillus parasiticus, Aspergillus pulverulentus, Cladosporium herbarum, Fusarium udum, Penicillium solitum, Rhizopus microspores, Gliocladium catenulatum, Fusarium culmorum and Aspergillus flavus. Pectinase activity of members of these fungal species was determined using well plate and DNS methods while, laccase activity was assessed by DMP method. The fungal strain Aspergillus pulverulentus, F23 gave the highest pectinase activity. This fungus produced 25.78 pectinase Unit/gram fungal biomass. The fungal strain Fusarium udum, F25 gave the highest laccase specific activity (0.930 U/mg) and resulted in increase of biomass accumulation (2.94 g/l). Strain Aspergillus flavus, F30 was active in producing of both pectinase and laccase enzymes at the same time. The specific activity of these enzymes was 89.54 and 0.840 U/mg respectively. The fungal specific activities of pectinase and laccase were determined throughout 15 days of incubation. The highest pectinase activity was noted with Aspergillus pulverulentus after 4 days of incubation resulting in pectinase specific activity of 2.265 U/ml, whereas this fungal strain and Fusarium udum, F25, were the highest in laccase production after 4 days of incubation. Optimization pectinase enzyme production was performed in relation to media pH and temperature of incubation. The storage stability of pectinase was also assessed.

Effect of radio frequency pretreatment on enzymatic retting of flax stems and resulting fibers properties

Radio frequency (RF) pretreatment of different water-presoaking time and RF treatment durations was introduced into enzymatic retting. RF pretreatment was used to degrade non-cellulosic materials and encourage the fast water-absorbing and swelling of the polar components in flax phloem, thus loosen the interfaces between fibers and fiber bundles and facilitate enzymes penetration. Retting efficiency, the resulting fibers properties and the water sorption after RF pretreatment were measured. It was found that the 8h-30min RF pretreatment improved retting efficiency most, increasing weight loss by 47 % and decreasing pectin content by 7.87 % compared to the control enzymatic retting and obtaining water sorption of 2.19. The results RF treated presoaked and non-presoaked flax were found to be different. The RF treatment of 30 min for the non-presoaked stems did not cause any improvement in pectin removal with a percentage decrease in pectin content of -8.41 %. The reason probably was that partial pectic substances in the non-presoaked flax phloem were dried, hardened and compacted during RF treatment. It was also found that RF pretreatment improved fibers whiteness and tended to weaken fibers tensile performance, and how it affected the fibers tensile properties was closely linked to the RF pretreatment processing.

Retting and degumming of flax using biotechnology eco-friendly approach

Flax retting is a treatment process employed to dissolve or rot away much of the cellular tissues and pectins surrounding bast/fiber bundles thus facilitating separation of the fiber from the stem. The microbial retting is one of the most environmentally friendly process. The rich source of microbes contributing to flax retting is the retting water in commercial retting plants. The main objective of this work is to accelerate the flax retting using selected bacterial strains contributing to retting and degumming of flax in order to avoid chemicals causing environmental pollution. In this work, reuse of retting water for acceleration of flax retting was tested. The results show that, the reuse of retted water in new cycle of flax retting has accelerated the retting completion by 8.3-25% depending on the ratio of reused retted water in the retting liquor. Therefore, samples of flax straw retted water and soils from flax fields located in Nile Valley and Delta soils were collected for isolation of flax retting bacteria predominant in the retting effluents. Identification of the isolates was done using morphological, physiological and biochemical tests. Ten bacterial isolates were identified as Lactococcus cremoris, Chryseobacterium culicis, Serratia marcescens, Capnocytophage granulose, Micrococcus luteus, Enterobacter homraechei, Klebsiella oxytoca, Paenibacillus polymyxa, Proteus mirabilis and Bacillus humi. Three efficient strains in pectinase production necessary for flax retting were selected to test their role in enhancing the retting process. These strains are Bacillus humi, Chryseobacterium culicis and Micrococcus luteus which showed specific pectinase activity 37.17, 33.53 and 28 Umg1 respectively.The effect of these strains on retting duration and fiber quality were studied. The combinations of the three strains were tested in the lab scale cylindrical experimental bioreactor and each of the combinations was compared with the classical retting process of the industrial units. The combined treatment using strains: Chryseobacterium culicis, Micrococcus luteus and Bacillus humi resulted in the reduction of the retting duration by 30%, whereas, the mixed inocula containing Chryseobacterium culicis and Micrococcus luteus reduced the retting time by 25%. The mixture of Micrococcus luteus and Bacillus humi reduced the retting duration by 20%. The determination of weight loss, tensile strength, whiteness and yellowness of the fibers after microbial retting was monitored. These present study showed that the obtained specific bacterial strains enhanced the retting process.

Effect of enzymatic treatment of flax on fineness of fibers and mechanical performance of composites

The application of enzymes as alternative to dew retting of flax was studied in correlation to the characteristics of composites reinforced with these natural fibers. Fiber fineness and mechanical properties of biocomposites were evaluated. Furthermore, moisture absorption by biocomposites was studied and fracture surfaces were investigated using Scanning Electron Microscopy. Compared to dew retted fiber composites, improvements in mechanical performance can be observed for composites impregnated with fibers extracted after enzymatic treatments. All enzymatic treatments resulted in finer fibers than green fibers and led to biocomposites with a reduced equilibrium moisture content and lower diffusion coefficient. This study illustrates the high potential of enzymatic retting, in particular with polygalacturonase. Also, the manual extraction procedure used, produced fibers with an E-modulus up to 84 GPa and strength up to 800 MPa, likely due to reduced fiber damage, which illustrates the hidden potential of flax fibers.

Evolution of flax cell wall ultrastructure and mechanical properties during the retting step

Flax retting is a major bioprocess in the cultivation and extraction cycle of flax fibres. The aim of the present study is to improve the understanding of the evolution of fibre properties and ultrastructure caused by this process at the plant cell wall scale. Initially, investigations of the mechanical performances of the flax cell walls by Atomic Force Microscopy (AFM) in Peak Force mode revealed a significant increase (+33%) in the cell wall indentation modulus with retting time. Two complementary structural studies are presented here, namely using X-Ray Diffraction (XRD) and solid state Nuclear Magnetic Resonance (NMR). An estimation of the cellulose crystallinity index by XRD measurements, confirmed by NMR, shows an increase of 8% in crystallinity with retting mainly due to the disappearance of amorphous polymer. In addition, NMR investigations show a compaction of inaccessible cell wall polymers, combined with an increase in the relaxation times of the C4 carbon. This densification provides a structural explanation for the observed improvement in mechanical performance of the secondary wall of flax fibres during the field retting process.

Production of Pectinolytic Enzymes by Two Bacillus spp. Strains and Their Application in Flax Degumming

This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of flax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these findings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were significantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out efficiently and quickly. The mixed system exhibits feasible applications in the fiber and textile industry.

The investigation of thinning of a layer of the long-fibred flax stems in a channel with adjustable cross-section

The rise in the proportion of long fiber in the commodity output of the primary processing enterprises of the fiber flax is an important task, the solution of which is necessary to increase the efficiency of the flax growing. More than half of the losses of long fiber cause a poor quality of preparation of a layer of flax retting to the processing. The technological processes of the existing layer preparation technology can not be adapted to the changed raw material parameters for the roll-up harvesting of the flax. In this regard, the urgency of the development of individual processes and a new technology in general for the preparation of a layer fed to the milling machine of the production line. The main technological process of layer preparation is its thinning. The linear density of the initial layer varies widely. To bring it to a technologically rational value, the equipment must provide a regulation of the coefficient of thinning. It is possible to provide this by using a thinning channel with adjustable cross-section. For its justification in the investigations the aim has been set to determine the influence of the structural and technological factors on the coefficient of thinning of the layer of flax. The investigations were carried out using active experiments on the prototype of this type of thinning channel created in VNIIML. The independent factors were: the linear density of the initial layer; linear velocity of the layer at the output from the thinning channel; height of the channel at the input and output from it. Two versions of the channel implementation are used: from one type of toothed discs with a number of teeth of 40 pieces.; combined - from two types of discs in equal proportion to the number of teeth 40 and 48 pcs. A significant influence on the thinning coefficient of the channel height layer at the input and output, as well as the linear density of the initial layer is determined. The possibility of adjusting the coefficient of thinning the layer by changing the cross-section of the thinning channel. It is established that the number of teeth on the thinning disks and the structure of the thinning channel exert a significant influence on the process of thinning the layer in the channels with free fixation of the stems. Mathematical models that adequately describe the influence on the coefficient of thinning of the investigated factors are presented. Conclusions are formulated about rational parameters of the thinning channel with a controlled cross-section and the expediency of its application for the thinning of the layer of flax.

Degumming crude enzyme produced by Bacillus cereus HDYM-02 and its application in flax retting

A cellulase-free, degumming crude enzyme was produced by Bacillus cereus HDYM-02, using konjaku flour as an inexpensive substrate. After 48 h fermentation, this crude enzyme consisted of pectinase and mannanase, whose maximum activity was 756.7 U/mL and 2967.3 U/mL, respectively. This crude enzyme exhibited considerable stability under the conditions resembling industrial flax retting. After 120 h incubation, more than 50% of the maximum activity of both pectinase and mannanase was retained at pH value 4.0 to 7.0, and at least 70% of the maximum activity was detected at 25 °C to 40 °C. The degumming liquid retted by this crude enzyme contained more galacturonic acid and reducing sugar than those in the degumming liquid retted by commercial pectinase. The application of B. cereus HDYM-02 crude enzyme resulted in higher weight loss of flax stems, better properties, higher productivities, and smoother surfaces of flax fibres. This study showed promise for the use of B. cereus HDYM-02 crude enzyme for flax retting in the textile industry.

Drastic changes in lake ecosystem development as a consequence of flax retting: a multiproxy palaeolimnological study of Lake Kooraste Linajärv, Estonia

This study demonstrates the power of multiproxy palaeolimnological analyses in investigating environmental changes in the Lake Kooraste Linajarv ecosystem through historical time in response to flax retting. Flax retting history was proven by applying pollen and macrofossil evidence and by using several biotic and geochemical proxies on a sediment core. Continuous findings of flax pollen and macrofossil remains in lake sediments were considered as strong evidence for the occurrence of retting. Analyses of the well-dated sediment core show the consequences of flax retting in the lake. As a result, the once clear soft water oligotrophic endorheic lake with limited sedimentation has turned into a hypertrophic high-sedimentation lake with anoxic bottom water, strong stratification and intense water blooms. Despite the fact that flax retting was forbidden in Estonia around ad 1950s and retting has not occurred over the last six decades, anthropogenic alterations were so pervasive in the past, that they have prevented any lake water improvements until the present-day.

Bacterial succession and metabolite changes during flax (Linum usitatissimum L.) retting with Bacillus cereus HDYM-02.

High-throughput sequencing and GC-MS (gas chromatography-mass spectrometry) were jointly used to reveal the bacterial succession and metabolite changes during flax (Linum usitatissimum L.) retting. The inoculation of Bacillus cereus HDYM-02 decreased bacterial richness and diversity. This inoculum led to the replacement of Enterobacteriaceae by Bacillaceae. The level of aerobic Pseudomonadaceae (mainly Azotobacter) and anaerobic Clostridiaceae_1 gradually increased and decreased, respectively. Following the addition of B. cereus HDYM-02, the dominant groups were all degumming enzyme producers or have been proven to be involved in microbial retting throughout the entire retting period. These results could be verified by the metabolite changes, either degumming enzymes or their catalytic products galacturonic acid and reducing sugars. The GC-MS data showed a clear separation between flax retting with and without B. cereus HDYM-02, particularly within the first 72 h. These findings reveal the important bacterial groups that are involved in fiber retting and will facilitate improvements in the retting process.

Mathematical analysis of compound release during microwave assisted retting of flax stems

Microwave-assisted retting was conducted at various power levels (1, 1.5 and 2 W g −1 ) on pre-soaked flax stems (12, 24 and 36 h). The retted flax stems were dried and the fibres were separated. The amount of cellulose, hemicellulose and lignin presented in the flax fibres was established by NIR (near infrared) spectroscopy. Based on the rate of change of cellulose, hemicellulose and lignin at various levels of treatments, a kinetic model was developed and the model was validated by analysing the compositions of hemp fibres obtained from pre-soaked hemp stems at various microwave power levels. The rate of change of cellulose percentage in the model fitted with the observed values of cellulose percentage with an average R 2 value of 0.87 and an average RMSE (root-mean-square error) value of 0.0130. But in hemicellulose, the R 2 value was 0.936 and average RMSE value was 0.0135, and for lignin, R 2 value was 0.92 and RMSE value of 0.0181. The rate coefficient for all the treatments was increasing within the treatment limit, which indicated the increased reaction rate with an increase in microwave power. Validation of the model was successfully conducted by analysing the components of hemp fibres at various levels of microwave powers.

Flax retting by degumming composite enzyme produced by Bacillus licheniformis HDYM-04 and effect on fiber properties

Flax enzymatic retting with composite enzyme produced by microbes with inexpensive substrates is widely researched due to less contamination and lower cost. Bacillus licheniformis HDYM-04, isolated from a liquid sample of flax retting pool, efficiently produced degumming enzymes after 48 h of fermentation with inexpensive konjaku flour, consisted of 587.5 U/mL pectinase, 365.2 U/mL mannanase, and 140.1 U/mL xylanase. Almost half the maximum activity of three above-mentioned degumming enzymes was maintained at pH 4.0–6.0 which demonstrated its stability in pH condition of flax retting. After 120 h of retting with this composite enzyme, scanning electronic microscopy showed more significant reduction in gummy components on the fiber surface than those of water retting. The fiber strength was 182.4 ± 9.3 N, 14.3% higher than water-retted samples. The long fiber rate and fiber yield also verified higher fiber productivity. The results permitted this degumming composite enzyme an applicable potential in flax retting.

Antimicrobial Properties of Flax Fibers in the Enzyme Retting Process

“GB/T 20944.3-2008--Part 3: Shake flask method” was applied to assess the antimicro bial property of flax fibres. The antimicrobial efficiency of flax fibre was represented as the absolute antimicrobial rate and relative antimicrobial rate. Cotton fibre served as a contrast in relation to the antimicrobial rate. The retted flax fibre showed an absolute anti microbial rate against E.coli and S. aureus, but only presented a relative antimicrobial rate against S. cerevisiae. The contents of pectic substances of flax straw such as cerolipoid, hydrotrope, pectin, hemicellulose and lignin declined during flax retting, especially lignin, whose content declined from 24% to 7.13%, and gaps appeared between the fibre bundles. Consequently the antimicrobial efficiency of flax fibre decreased gradually. This experiment confirmed the existence of antibacterial substances, but exactly what compounds associ ated with flax exhibiting antimicrobial properties is not discussed.