Production and toxicity evaluation of Rhamnolipids produced by Pseudomonas strains on L6 and Hepg2 cells

Biosurfactant rhamnolipid (RL) production using renewable resource is gaining attraction for commercial application. In this study, RL produced from three different strains of Pseudomonas using glycerol as a carbon source was used to evaluate toxicity towards rat skeletal muscle (L6) and liver cancer (HepG2) cells. In the present study, Pseudomonas aeruginosa PAO1 produced the highest concentration of RL (1.53 ± 0.28 g/L) and able to reduce the surface tension (ST) value of water the lowest (29.1 ± 0.5 mN/m). Toxicity evaluation using MTT assay indicated that RL produced does not have a cytotoxic effect towards both cell lines except where 50% inhibition concentration (IC50) was detected for HepG2 only at high concentration (100 µg/mL) for RL produced by P. aeruginosa PAO1. The RL produced by strains in this study is nontoxic with good ST reducing ability that has potential applications in food, cosmetics and pharmaceutical sector

The Influence of Stationary and exponential Growth Phase of Probiotic Lactobacilli Towards Aggregatibacter actinomycetemcomitans Biofilm

Background: Bacterial biofilm of the oral cavity contributes to the dispersion of pathogenic organisms to other organs, particularly in immunocompromised patients. Lactobacilli own potent activity against the biofilm of the periodontal pathogen. The study aims to evaluate the inhibition activity of the probiotics lactobacilli’s cells and supernatant during exponential and stationary phases against Aggregatibacter actinomycetemcomitans’s biofilm exponential phase.Methods: Five Lactobacillus sp. and four A. actinomycetemcomitans strains were used during preliminary studies. Then, two chosen species of Lactobacillus sp. were used to determine inhibition activity towards A. actinomycetemcomitans’s biofilm using biofilm inhibition assay of a 96-well plate. Data of three replicates were presented as mean ± SD (standard deviation). The comparison was performed using Student t-test Software with P-value 0.05) in inhibition activity between the exponential and stationary phase of L. johnsonii NBRC 13952 in both cells and supernatant.Conclusion: This finding suggests a dynamic effect of the probiotic Lactobacillus sp. as part of counteraction strategies against the periodontal pathogen biofilm. The differential effect of stationary and exponential phases might indicate different mechanisms or compounds that require further study.Keywords: Aggregatibacter actinomycetemcomitans; Periodontal disease; Biofilm formation; Probiotic lactobacilli; Biofilm inhibitio

Composition of Ballast Water from Ships Arriving at Kertih Port, Malaysia with Observations on Port and Offshore Waters, and Notes on Settlement Patterns of Fouling Organisms

We investigated plankton composition and water quality of ballast water from seven international ships docked at Kertih Port, Malaysia. Coscinodiscophyceae and cyanobacteria were the dominant phytoplankton found in ballast water samples, whereas copepod nauplii, Oithona sp., Microstella sp. and Paracalanus sp. were the dominant zooplankton. The densities for both phytoplankton and zooplankton in ships’ ballast and port waters were higher than those of offshore samples. All water quality parameters (except Cr) of port samples were within the safety levels prescribed for ports, oil and gas fields (Class 3) by the Malaysia Marine Water Quality Criteria Standard. The study of fouling organisms using PVC panels revealed that brown algae covered 87–95% of the panels’ surface area but they were subsequently succeeded by barnacles, bivalves and red encrusting algae. Barnacle recruitment, however, was greatly influenced by crab predation which left behind a high percentage cover of barnacle bases as calcareous deposits on panels

Positive and negative effects of COVID-19 pandemic on aquatic environment: a review

In December 2019, a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak was reported for the first time in Wuhan, Hubei province, China. This coronavirus has been referred as Coronavirus Disease 2019 or COVID-19 by World Health Organization (WHO). The spread of COVID-19 has become unstoppable, infecting around 93.5 million people worldwide, with the infections and deaths still increasing. Today, the entire planet has changed due to the greatest threat on the planet since the introduction of this lethal disease. This pandemic has left the world in turmoil and various measures have been taken by many countries including movement control order or lockdown, to slow down or mitigate the infection. Since the lockdown has been implemented almost in all affected countries, there has been a significant reduction in anthropogenic activity, including a reduction in industrial operations, vehicle numbers, and marine-related activities. All of these changes have also led to some unexpected environmental consequences. As a result of this lockdown, it had a positive and negative impact on the environment including the aquatic environment. Hence this review will therefore focus on the good and bad perspectives of the lockdown toward the aquatic environment

A Critical Review on the Economically Feasible and Sustainable Poly(3-Hydroxybutyrate-<i>co</i>-3-hydroxyvalerate) Production from Alkyl Alcohols

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) is the most studied short-chain-length polyhydroxyalkanoates (PHA) with high application importance in various fields. The domination of high-cost propionate and valerate over other 3-hydroxyvalerate (3HV) precursors owing to their wide preference among PHA-producing bacteria has hindered the development of diverse production processes. As alkyl alcohols are mainly produced from inexpensive starting materials through oxo synthesis, they contribute a cost-effective advantage over propionate and valerate. Moreover, alkyl alcohols can be biosynthesized from natural substrates and organic wastes. Despite their great potential, their toxicity to most PHA-producing bacteria has been the major drawback for their wide implementation as 3HV precursors for decades. Although the standard PHA-producing bacteria Cupriavidus necator showed promising alcohol tolerance, the 3HV yield was discouraging. Continuous discovery of alkyl alcohols-utilizing PHA-producing bacteria has enabled broader choices in 3HV precursor selection for diverse P(3HB-co-3HV) production processes with higher economic feasibility. Besides continuous effort in searching for promising wild-type strains, genetic engineering to construct promising recombinant strains based on the understanding of the mechanisms involved in alkyl alcohols toxicity and tolerance is an alternative approach. However, more studies are required for techno-economic assessment to analyze the economic performance of alkyl alcohol-based production compared to that of organic acids

Data on partial polyhydroxyalkanoate synthase genes (phaC) mined from Aaptos aaptos marine sponge-associated bacteria metagenome

We report data associated with the identification of three polyhydroxyalkanoate synthase genes (phaC) isolated from the marine bacteria metagenome of Aaptos aaptos marine sponge in the waters of Bidong Island, Terengganu, Malaysia. Our data describe the extraction of bacterial metagenome from sponge tissue, measurement of purity and concentration of extracted metagenome, polymerase chain reaction (PCR)-mediated amplification using degenerate primers targeting Class I and II phaC genes, sequencing at First BASE Laboratories Sdn Bhd, and phylogenetic analysis of identified and known phaC genes. The partial nucleotide sequences were aligned, refined, compared with the Basic Local Alignment Search Tool (BLAST) databases, and released online in GenBank. The data include the identified partial putative phaC and their GenBank accession numbers, which are Rhodocista sp. phaC (MF457754), Pseudomonas sp. phaC (MF437016), and an uncultured bacterium AR5-9d_16 phaC (MF457753). Keywords: Marine sponge, Metagenome, Polyhydroxyalkanoate synthase gene, Phylogenetic analysi

Extracellular Polyhydroxyalkanoate Depolymerase by Acidovorax sp. DP5

Bacteria capable of degrading polyhydroxyalkanoates (PHA) by secreting extracellular depolymerase enzymes were isolated from water and soil samples collected from various environments in Malaysia. A total of 8 potential degraders exhibited clear zones on poly(3-hydroxybutyrate) [P(3HB)] based agar, indicating the presence of extracellular PHA depolymerase. Among the isolates, DP5 exhibited the largest clearing zone with a degradation index of 6.0. The highest degradation activity of P(3HB) was also observed with depolymerase enzyme of DP5 in mineral salt medium containing P(3HB). Based on biochemical characterization and 16S rRNA cloning and sequencing, isolate DP5 was found to belong to the genus Acidovorax and subsequently named as Acidovorax sp. DP5. The highest extracellular depolymerase enzyme activity was achieved when 0.25% (w/v) of P(3HB) and 1 g/L of urea were used as carbon and nitrogen source, respectively, in the culture media. The most suitable assay condition of the depolymerase enzyme in response to pH and temperature was tested. The depolymerase produced by strain Acidovorax sp. DP5 showed high percentage of degradation with P(3HB) films in an alkaline condition with pH 9 and at a temperature of 40°C

Dataset on controlled production of polyhydroxyalkanoate-based microbead using double emulsion solvent evaporation technique

A significant source of microplastics is from the usage of microbeads in the market since petrochemical plastic bead is a material used in cosmetic scrubs. A possible way to counteract the problem is by the substitution of synthetic plastic to natural biodegradable polymer. Polyhydroxyalkanoate (PHA) is a general class of thermoplastic microbial polymer and it is the best alternative to some petrochemical plastics due to its biodegradability. Some PHA has earned its way into cosmetic application due to its biocompatibility. This data article reports data on the development of biodegradable microbeads by using the double emulsion solvent evaporation technique. Our data describe the extraction of biopolymer from marine bacteria that was cultivated in shaken flask culture, removal of endotoxins using oxidizing agent, the production of microbeads using a peristaltic pump with a specific flowrate and silicon tubing, and the cytotoxicity of the microbeads. Keywords: Masillia haematophilla UMTKB-2, Polyhydroxyalkanoate, Microbeads, Cosmeceutica

Polyhydroxyalkanoate (PHA) Biopolymer Synthesis by Marine Bacteria of the Malaysian Coral Triangle Region and Mining for PHA Synthase Genes

Polyhydroxyalkanoate (PHA), a biodegradable and plastic-like biopolymer, has been receiving research and industrial attention due to severe plastic pollution, resource depletion, and global waste issues. This has spurred the isolation and characterisation of novel PHA-producing strains through cultivation and non-cultivation approaches, with a particular interest in genes encoding PHA synthesis pathways. Since sea sponges and sediment are marine benthic habitats known to be rich in microbial diversity, sponge tissues (Xestospongia muta and Aaptos aaptos) and sediment samples were collected in this study from Redang and Bidong islands located in the Malaysian Coral Triangle region. PHA synthase (phaC) genes were identified from sediment-associated bacterial strains using a cultivation approach and from sponge-associated bacterial metagenomes using a non-cultivation approach. In addition, phylogenetic diversity profiling was performed for the sponge-associated bacterial community using 16S ribosomal ribonucleic acid (16S rRNA) amplicon sequencing to screen for the potential presence of PHA-producer taxa. A total of three phaC genes from the bacterial metagenome of Aaptos and three phaC genes from sediment isolates (Sphingobacterium mizutaii UMTKB-6, Alcaligenes faecalis UMTKB-7, Acinetobacter calcoaceticus UMTKB-8) were identified. Produced PHA polymers were shown to be composed of 5C to nC monomers, with previously unreported PHA-producing ability of the S. mizutaii strain, as well as a 3-hydroxyvalerate-synthesising ability without precursor addition by the A. calcoaceticus strain