Ramie (<em>Boehmeria nivea</em>) Gum: A Natural Feed to Sustain and Stimulate the Growth of Bacteria

Research Article

Bacteriol Mycol. 2018; 5(2): 1067.

Ramie (Boehmeria nivea) Gum: A Natural Feed to Sustain and Stimulate the Growth of Bacteria

Banerjee S1, Gupta M2, Roy A2, Chakraborty A1 and Ray Chaudhuri S1*

¹Department of Microbiology, Tripura University, Suryamaninagar, India

²Centre of Excellence in Environmental Technology and Management, Maulana AbulKalam Azad University of Technology, West Bengal, India

*Corresponding author: Shaon Ray Chaudhuri, Department of Microbiology, Tripura University, Suryamaninagar, India

Received: April 06, 2018; Accepted: May 03, 2018; Published: May 10, 2018


Bacteria require nutrients to sustain growth. For most of the commonly used complex media, the components are obtained from animal slaughter and are expensive. They support growth but when discharged, lead to environmental pollution and sustain growth of undesirable microbes. Thus it is necessary to look for cheaper and less enriched alternative sources for bacterial nutrition. Gum (1% w/v) from the decorticated fibers of Boehmeria nivea (Ramie), supported growth to different extent for both Bacillus sp and Pseudomonas sp. The growth was further enhanced with addition of Tryptone, Yeast Extract and sodium chloride (Luria Bertini broth) to the gum at a ratio of 1:3 for bacteria of both Genus Bacillus and Pseudomonas. This could be an alternative bacterial growth option for activities resulting in environmental discharge of the effluent like fiber degumming, waste water treatment, biofertilizer production, to name a few.

Keywords: Ramie; Gum; Bacterial Feed; Growth


All living organisms require food to grow, reproduce and carry out their normal metabolic functions, and so does bacteria. They usually utilize organic matter to derive energy. The dependence is more on simpler substances with low molecular weight which can be easily broken down by extracellular enzymes [1]. They can live on a range of substances ranging from starch, milk, wood and even sulphur. Some thrive on substances such as body fluids in which they live [9].

For the cultivation of bacteria in the laboratory, two types of complex media, Nutrient broth and Luria Bertani (LB) broth are routinely used. They are composed of substances like beef extract, peptone, tryptone which are obtained from animal slaughter, making them costly and not environment friendly during discharge. Thus it would be beneficial if the use of such materials could be reduced if not replaced with products from plant origin. It would in turn reduce grain and water consumption used for animal feeding while reduces environmental pollution due to discharge of used medium following large scale cultivation.

Many plants like Boehmeria nivea (Ramie) produce gum as a secondary metabolite [11] resulting from cellulose disintegration [5] and is often unwanted for the plant themselves as well as the plant derived products like fiber for fabric production. For textile industry, the Ramie bast fiber, after the removal of gum by natural or chemical means is used for the production of fabrics which is often blended with other fibers such as cotton [8]. During the process of natural retting, the fibers dipped in water swell due to water penetration where the outer layers absorb moisture and become more exposed to decay causing bacteria. In this process the gum from the bastfibers oozes out into the water in which it remains dipped for a standard period of time [10]. The Ramie gum composed of cellulose, hemicellulose, lignin and pectin is a rich carbon source [3] which is usually discarded after degumming, contaminating the environment. These gum constituents are reported to be utilized by bacteria [7,12,2] provided they would break down these constituents into simpler form. With this background knowledge we attempted to utilize the Ramie gum as a feed for bacteria with an objective to minimize cost as well as environmental damages.

Materials and Methods

Standardization of natural retting at laboratory scale

Decorticated Ramie fibers obtained from Indian Institute of Technology, Kharagpur (IITKGP), West Bengal, India were dipped in tap water and the process of natural degumming was standardized 6. The gum was extracted from the liquor component [4].

Gum as microbial feed

The extracted gum was used at a concentration of 1% (w/v) in water to prepare liquid medium for bacterial growth. Two sets of medium were prepared: One was sterilized by filtration through 0.45μm filter units inside a laminar flow hood, and the other was sterilized at 15 psi for 15 minutes. Each set was separately inoculated with Bacillus sp (SRC 005, SRC 007, MCC2138, MTCC 11281, MCC2071, MCC2059, MCC0008) and Pseudomonas sp (SRC 001, MTCC 5564 and SRC 004) followed by incubation for 16 hours at 37°C and shaking instead of 200 rpm (SI - 300 Lab Companion). Growth in terms of the optical density at 600nm (Eppendorf bio Spectrophotometer) was measured and compared among the sets to check for the presence of thermo labile components in the gum.

Media containing different ratios (1:3, 1:1, 3:1) of gum with LB were prepared to check the impact of the combination on microbial growth. As control different percentages of LB (25%, 50%, 75% and 100%) were used. LB at 100% concentration consisted of 1% Tryptone, 0.5% sodium chloride and 0.5% Yeast Extract. Each media preparation was sterilized by autoclaving at 15 psi for 15 minutes.

Seven different strains of Bacillus sp and three different strains of Pseudomonas sp, as mentioned above, were inoculated (1% v/v) and incubated overnight. The optical density was measured to determine the optimum combination to support bacterial growth using gum.

Amount of gum extracted from identical weight of Ramie fiber is an indication of the amount of gum produced in response to any treatment. The impact of fertilizer [chemical (NPK), vermicompost (generated using dried Ramie cortex and leaves), and liquid biofertilizer] application on the gum production in Ramie was assessed using standard method [6].

Statistical validation

All of the statistical tests were performed using Microsoft Excel 2007. A t-test was conducted at the 5% level of significance to evaluate the validity of the results.

Results and Discussion

The gum extraction indicated maximum degumming within 72 hours at 40°C (room temperature in June 2015) with a fiber: Liquor ratio of 1:8 [6].

The various isolates displayed different extents of growth in autoclaved and filter sterile gum solution. Some isolates (MCC2138, MCC2059, SRC 005, SRC 007 and SRC 004) exhibited better growth in filter-sterilized gum, indicating requirement of thermolabile gum components that might have degraded during autoclaving. The remaining isolates grew well in autoclaved gum, which indicated that the thermolabile components in the gum solution had an inhibitory effect on their growth (Figure 1). While pectine degrades at elevated temperature (45o to 58oC), hemicellulose degrades at elevated pressure. These could be responsible for the variation in bacterial growth with and without autoclaving the gum solution.