As a major food crop, rice (Oryza sativa) is produced and consumed by nearly 90% of the population in Asia with less than 9% produced outside Asia. Hence, reports on large scale grain losses were alarming and resulted in a heightened awareness on the importance of rice plants’ health and increased interest against phytopathogens in rice. To serve this interest, this review will provide a summary on bacterial rice pathogens, which can potentially be controlled by plant growth-promoting bacteria (PGPB). Additionally, this review highlights PGPB-mediated functional traits, including biocontrol of bacterial rice pathogens and enhancement of rice plant’s growth. Currently, a plethora of recent studies address the use of PGPB to combat bacterial rice pathogens in an attempt to replace existing methods of chemical fertilizers and pesticides that often lead to environmental pollutions. As a tool to combat bacterial rice pathogens, PGPB presented itself as a promising alternative in improving rice plants’ health and simultaneously controlling bacterial rice pathogens in vitro and in the field/greenhouse studies. PGPB, such as Bacillus, Pseudomonas, Enterobacter, Streptomyces, are now very well-known. Applications of PGPB as bioformulations are found to be effective in improving rice productivity and provide an eco-friendly alternative to agroecosystems.

Bacteria are present in stingless bee nest products. However, detailed information on their characteristics is scarce. Thus, this study aims to investigate the characteristics of bacterial species isolated from Malaysian stingless bee,Heterotrigona itama, nest products. Honey, bee bread and propolis were collected aseptically from four geographical localities of Malaysia. Total plate count (TPC), bacterial identification, phenotypic profile and enzymatic and antibacterial activities were studied. The results indicated that the number of TPC varies from one location to another. A total of 41 different bacterial isolates from the phyla Firmicutes, Proteobacteria and Actinobacteria were identified.Bacillusspecies were the major bacteria found. Therein,Bacillus cereuswas the most frequently isolated species followed byBacillus aryabhattai,Bacillus oleronius,Bacillus stratosphericus,Bacillus altitudinis,Bacillus amyloliquefaciens,Bacillus nealsonii,Bacillus toyonensis,Bacillus subtilis,Bacillus safensis,Bacillus pseudomycoides,Enterobacter asburiae,Enterobacter cloacae,Pantoea dispersaandStreptomyces kunmingensis. Phenotypic profile of 15 bacterial isolates using GEN III MicroPlate™ system revealed most of the isolates as capable to utilise carbohydrates as well as amino acids and carboxylic acids and derivatives. Proteolytic, lipolytic and cellulolytic activities as determined by enzymatic assays were detected inBacillus stratosphericusPD6,Bacillus amyloliquefaciensPD9,Bacillus subtilisBD3 andBacillus safensisBD9.Bacillus amyloliquefaciensPD9 showed broad-spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria in vitro. The multienzymes and antimicrobial activities exhibited by the bacterial isolates fromH. itamanest products could provide potential sources of enzymes and antimicrobial compounds for biotechnological applications.

Background: Numerous prevalence studies ofVibriospp. infection in fish have been extensively reported worldwide, including Malaysia. Unfortunately, information on the prevalence ofVibriospp. in groupers (Epinephelusspp.) is limited. In this study, groupers obtained from nine farms located at different geographical regions in Malaysia were sampled for the presence of pathogenicVibriospp. and their susceptibility profiles against seven antibiotics.Results: Out of 270 grouper samples, 195 (72%) were detected with the presence ofVibriospp.Vibrio communisshowed highest prevalence in grouper (28%), followed byV. parahaemolyticus(25%),V. alginolyticus(19%),V. vulnificus(14%),V. rotiferianus(3%),Vibriosp. (3%),V. campbellii(2%), V. mytili(2%), V. furnissii(2%), V. harveyi(1%), V. tubiashii(1%), V. fluvialis(0.3%) andV. diabolicus(0.3%).Assessment on the antibiotic susceptibility profiles of theVibriospp. revealed that majority of the isolates were susceptible to tetracycline, streptomycin, erythromycin and bacitracin, but resistance to ampicillin, penicillin G and vancomycin. The mean MAR index of theVibrioisolates was 0.51, with 85% of the isolates showed MAR index value of higher than 0.2. Results indicate that theVibriospp. were continuously exposed to antibiotics. Furthermore, the plasmid profiles ofVibriospp. showed that 38.7% of the isolates harbored plasmid with molecular weight of more than 10 kb, while 61.3% were without plasmid. During curing process,Vibriospp. lost their plasmid, but remained resistant to ampicillin, penicillin G, bacitracin and vancomycin while a few isolates remained resistant to erythromycin, streptomycin and tetracycline. The results suggested that the resistance to antibiotics in isolatedVibriospp. might be due to chromosomal and plasmid borne.Conclusions: This study demonstrates the prevalence ofVibriospp. in groupers and the distribution of multidrug resistance strains that could be of concern to the farmers in Malaysia. In addition, data from this study can be further used in fish disease management plan.

Ganoderma boninense is the causal agent of a devastating disease affecting oil palm in Southeast Asian countries. Basal stem rot (BSR) disease slowly rots the base of palms, which radically reduces productive lifespan of this lucrative crop. Previous reports have indicated the successful use of Trichoderma as biological control agent (BCA) against G. boninense and isolate T. virens 7b was selected based on its initial screening. This study attempts to decipher the mechanisms responsible for the inhibition of G. boninense by identifying and characterizing the chemical compounds as well as the physical mechanisms by T. virens 7b. Hexane extract of the isolate gave 62.60% ± 6.41 inhibition against G. boninense and observation under scanning electron microscope (SEM) detected severe mycelial deformation of the pathogen at the region of inhibition. Similar mycelia deformation of G. boninense was observed with a fungicide treatment, Benlate^® indicating comparable fungicidal effect by T. virens 7b. Fraction 4 and 5 of hexane active fractions through preparative thin layer chromatography (P-TLC) was identified giving the best inhibition of the pathogen. These fractions comprised of ketones, alcohols, aldehydes, lactones, sesquiterpenes, monoterpenes, sulphides, and free fatty acids profiled through gas chromatography mass spectrometry detector (GC/MSD). A novel antifungal compound discovery of phenylethyl alcohol (PEA) by T. virens 7b is reported through this study. T. virens 7b also proved to be an active siderophore producer through chrome azurol S (CAS) agar assay. The study demonstrated the possible mechanisms involved and responsible in the successful inhibition of G. boninense.